The story so far: In the beginning the Universe was created. This has made a lot of people very angry and has been widely regarded as a bad move...

Wait a sec, that's the Hitchhiker's guide to the galaxy... :)

The story of this RCA, found ( rescued ) from a High School vocational electronics class, ( original problem , no color ), after some pretty dumb things were done to it, including , removing the color PCB.

I tried to fix it back then, but did not have much time to devote to it, since then, It has sat in storage waiting all these years, exposed to the cold of winter and the heat of summer. ( I'm sure the caps hated this, especially the electrolytics)

Last dec, I decided to pull it out and start working on it again, after much checking, I'm pretty sure ( not 100% ) that the color PCB is back in and hooked up correctly.
So, I dared to turn it on... no smoke, no explosions, no popped breakers, and after replacing the bad HV rec and reg, I got High voltage, and a raster ( very ugly ) no video yet. 21Fjp22a in great shape 3 good guns.

I'm still in the process of changing the main electrolytics, but I did see something a bit strange, C1a has been changed, but I still see a strong sawtooth wave there (before L45 and not after ) at about 10v when first turned on raising to 30v as tubes warm up and HV kicks on.

I'm pretty sure that sawtooth should not be there, or be that high, as mentioned, C1A has been replaced, (85uf 500v ) I may try something larger, I have NOT replaced C3B yet ( it may be coming from there.) and plan to replace the other electrolytics 1 at a time, to see if this goes away, I am also in suspect of the main LV rect diodes, they MAY be flaky, orig replacements are hard to find, so I'm guessing that 1N4005G dioded should be OK.

Once I get power stable on this thing, then I can worry about cleaning all the dirty pots and switches ( and tuner :/ ) and trying to get a video to show on it again...
I'm hoping that deoxit is a good choice for cleaning the tuner. :/

As I mentioned, I am in the process of re-capping my RCA CTC-16XL,
The electrolytics mainly to start with, to get stable power, as it's been sitting for 30 years.
But there is one section in the multi cans, that does NOT look like power filtering, but part of AGC, and unlike the PWS section, if I replace with anything larger that what was in there, it can drastically change how it works.

C1 section c 40uf, ( see attached )
making a guess here, this is a feedback circuit off the output of video amp 2 , via the delay line, L13, L14, to set cathode bias on v6, (a/b) , so there is no wiggle room on that cap, it MUST be 40uf...
Am I reading it right?
https://imgur.com/a/iG2mCf6

C1 looks to be a cathode bypass/filter cap..... there's no such thing as a precision lytics in tube electronics....they all were rated -50% +100% capacitance tolerance. A 47uF or if your feeling persnickety a 39uF will both work fine.

40 is part of the old standard.of parts valuing that was on its way out when that set was new...So your not going to find a newly made 40.

Then the 56uF 80Volts cap I have should be OK then. but I'll replace that one last.

I may be overthinking this, but to me , this sawtooth wave here (at C1a) just does not seem right, but the SAMS does not have a reference for a wave at that exact point, I have replaced C1a with an much larger cap and am still seeing it, its mostly filtered out by L45, but I don't think it should be there at all, its still present at the end of the 400v source ( very faint )

I'm running the set with HV disabled ( yolk disconnected ) when this wave was captured.
I have not replaced the LV rects yet ( they are hard to get to ) but I plan to, as I suspect them to be a problem. ( unless someone thinks that sawtooth I'm seeing is normal :o ) as mentioned, I chose 1N4005G for that as they looked rather close to what was in there..

https://imgur.com/a/U5mvTBT
https://imgur.com/a/6vEuABP

replacing the LV diodes did not make that sawtooth wave at that point any better, so i't most likely normal, I DO get the 1v wave, as shown in the Sams on the other side of L45, i'm 1/2 way through replacing the main filter caps.
I still need to clean all the POTs and the tuner, to try to get it to get some picture on the screen, however, I may just bypass the tuner and IF all together and tap in video at the 1st video amp, to save time, ( around L9 ) as shown below.
https://imgur.com/a/PHTuOE9

The one thing i dread the most is... once all the electronic stuff is out of the way, fixing that damn cataract. T_T

https://imgur.com/a/d7cvF8P

That cat don't look too bad...A little more and it would fall off on it's own. Come summer put it face up in a 5 gal bucket or trash can, remove the tape around the edge, with a VERY thin screwdriver gouge out several 1" radius chunks of the glue (don't pry on the glass), then take halves of wooden clothes pins and wedge them in to the radiuses you removed, place it in the sun with a black garbage bag over it's face. Every 15-30 min tap the wedges in a bit. Gradually the safety glass will come off...The biggest enemy is impatience I've ruined 2/3 of the safety glass I've done this on by applying too much force too fast.

When your done peel and fingernail scratch all the old glue off, clean bulk residue with goofoff, then get streak free with glass cleaner. You can reattach the safety glass by at 4 even spaces along the edge placing 1/8"-1/4" thich foam double stick tape strips as gap spacers. then caulk the edge. Make sure it is ABSOLUTELY spotless before setting the glass on (any dust, spot or lint will be a pain to go back and get). And make sure the spacers and caulk are at least 1/4" outside the edge of the phosphor viewing surface...(otherwise, when the CRT is in the set you'll see it and be sad).

What kind of sucks now is, there is no easy way to test tubes... long ago, when I was a kid, there were testers all over the place, but now, if you go asking for one, they look at you like you have 3 heads and tentacles for arms. And yes, you can find some old portable ones on E-bay, but who knows how well they work, ( if at all. ) :(

What kind of sucks now is, there is no easy way to test tubes... long ago, when I was a kid, there were testers all over the place, but now, if you go asking for one, they look at you like you have 3 heads and tentacles for arms. And yes, you can find some old portable ones on E-bay, but who knows how well they work, ( if at all. ) :(

I've always considered drugstore testers as a waste of space.... get a portable like the B&K 606 I use predominantly.... any tester at this point is equally at risk of inaccurate readings. Most "portable" service testers have published service and calibration online. You can run thru a cal and if it fails just change a handful of resistors and caps and next time it should pass.

Also some tubes like sweep and HV cannot be accurately tested on any tester because no tester was made to deliver the high current and or high voltage the tube gets subjected to in normal applications. I seen plenty of HV rects and other sweep tubes where readings in multiple testers don't match actuall in set performance.

Nice anime catgirl avatar ya got.

I may be overthinking this, but to me , this sawtooth wave here (at C1a) just does not seem right, but the SAMS does not have a reference for a wave at that exact point, I have replaced C1a with an much larger cap and am still seeing it, its mostly filtered out by L45, but I don't think it should be there at all, its still present at the end of the 400v source ( very faint )

I'm running the set with HV disabled ( yolk disconnected ) when this wave was captured.
I have not replaced the LV rects yet ( they are hard to get to ) but I plan to, as I suspect them to be a problem. ( unless someone thinks that sawtooth I'm seeing is normal :o ) as mentioned, I chose 1N4005G for that as they looked rather close to what was in there..

https://imgur.com/a/U5mvTBT
https://imgur.com/a/6vEuABP

If you're getting a sawtooth waveform at first filter capacitor, don't be too surprised. These sets use a voltage doubler power supply, and it's going to have lots of ripple at the first filter. In other words, I'd kind of expect a sawtooth there.

Where did you get C1A from? What cap is it on the RCA schematic? Is that a sams or an RCA part number?

https://www.boxcarcabin.com/rcaschematics.html has most of the early rca schematics.

I sold my CTC16 some time ago, but it was a cool TV. Make sure to check for bad soldering of power resistors, and also I'd go over the chassis ground points. The spots where the boards are soldered to the chassis can cause intermittent issues if the solder isn't good, it would be a good idea to re-flow them. Clean all the tube sockets too.

If you're getting a sawtooth waveform at first filter capacitor, don't be too surprised. These sets use a voltage doubler power supply, and it's going to have lots of ripple at the first filter. In other words, I'd kind of expect a sawtooth there.

Where did you get C1A from? What cap is it on the RCA schematic? Is that a sams or an RCA part number?

https://www.boxcarcabin.com/rcaschematics.html has most of the early rca schematics.

I sold my CTC16 some time ago, but it was a cool TV. Make sure to check for bad soldering of power resistors, and also I'd go over the chassis ground points. The spots where the boards are soldered to the chassis can cause intermittent issues if the solder isn't good, it would be a good idea to re-flow them. Clean all the tube sockets too.

I'm going from the sams , that matches my CTC-16XL (set 812 folder 2 )
there is slight difference in the CTC-16 vs CTC-16X, so much that they have different releases . but both have full bridge rectifiers, and look nothing like voltage doubler in the link you shown (odd) , the bridge and C1 a is in a link i pasted above, Was 80uf, (400v) now is 100uf (500v)

I took a peek at all RCA color types leading up to the ctc-16, I'm not sure what rev that was in your link, but it's not a 16, for the following, when they came out with the 16, the voltage doubler was removed when they added the degaussing coil circuit, also, some of the tube types dont match up with what is in the set as shown.

I'm going from the sams , that matches my CTC-16XL (set 812 folder 2 )
there is slight difference in the CTC-16 vs CTC-16X, so much that they have different releases . but both have full bridge rectifiers, and look nothing like voltage doubler in the link you shown (odd) , the bridge and C1 a is in a link i pasted above, Was 80uf, (400v) now is 100uf (500v)

I took a peek at all RCA color types leading up to the ctc-16, I'm not sure what rev that was in your link, but it's not a 16, for the following, when they came out with the 16, the voltage doubler was removed when they added the degaussing coil circuit, also, some of the tube types dont match up with what is in the set as shown.

There were about 6 schematics in the boxcarcabin link.... easy to miss unless you zoom out and scroll... The CTC16 a in 2 variants is there near the bottom.

On that RCA schematic it's C118a then, ( I did not see it at the bottom)
I still prefer the Sams, cause it's easier to see, and has much more info, like waveforms.

On that RCA schematic it's C118a then, ( I did not see it at the bottom)
I still prefer the Sams, cause it's easier to see, and has much more info, like waveforms.

If C118A, then I would expect a sawtooth and that ripple magnitude sounds about right. That sawtooth is just the capacitor discharging as load current is drawn and then recovering as the rectified AC input waveform recharges it. The ripple is high here since this is the first filter capacitor.

For checking tubes, substitution is always your best bet. It would make sense to have on hand spares for most of the tubes in that set. Drugstore testers were more about tube sales than thorough tube testing.. for a really good test, a mutual conductance type tester is always best, but not really worth getting until you're surrounded by tube equipment needing repair. If you want to find one locally, figure out where audiophile, ham radio enthusiasts, or antique radio collectors hang out, you'll probably be able to borrow one, or at least bring your tubes to someone to check.

I have COLOR!!!

https://imgur.com/a/ttpXARP


I still have much work to do... yes,

my color / bar generator is broken , so I took a VCR and tapped in a video at the first video amp and that is what i got.

the yoke has been off, so nothing is adjusted, all out of focus , but this is a BIG step forward! :D:banana:

This is probably going to take a LOOONG time to get working correctly. :(
not that I did not expect this, after it sitting in storage for so long :/
I still can't get anything through the tuner/if yet , no telltale HISS from the speaker, ( but there is a faint hum/ hiss heard ) .

60% of filter (electrolytics) replaced,
when turned on I do get HV and raster, and when I tap in video to the point mentioned at 1st video anp , I get a fuzzy video ( levels are prob not correct impedance for the tap ) but I see the video with color, and have vert / horz lock.

Trying to find a tube tester.

Am i going to have to end up checking every resistor / cap in this thing? T_T
Well if that is what it takes...

Try wiggling the IF tubes. If the first IF gives pix noise and or sound noise then the problem is in the tuner if not it is in or before the lowest IF tube number that gives noise when wiggled. Another possibility is the AGC is missadjusted or broken....In that era of RCA the AGC checks the sync level in the video signal every horizontal pulse and adjusts the tuner and IF gain (by changing the grid bias of the tuner and IF tubes) to hold the video level constant.... the AGC control should be able to take the set from blank raster with no signal passing through to normal signal then on to excessive overdriven video that won't sync.... circuit failure can hold it in an exterme state.

i will prob start poking around the IF section once the rest of the caps are replaced and tubes tested.
FYI, this is the video i was injecting, https://imgur.com/a/z4Sh5ZD
taken by crappy cellphone camera on a tiny 3 inch color analog monitor i have.
I'm just very happy the color works on my CTC :)

It would probably be much more productive to send an actual image rather than a colored raster. You can check if your color, focus, sweep linearity, etc are good. That blue field you sent it will hide many issues that might be good to know about now.

Also (if you haven't already done this) before you go running it for more than 10 min stints it would be wise to go through the sam's horizontal setup procedure (especially checking and minimizing horizontal output cathode current)...These sets can cook their own flybacks really easy if everything ain't just right,

It's true that I do not have it on very long when I do turn it on, and I have not yet run the horizontal setup procedure , as it says “ tune in a TV station and set controls for normal operation” However, this can prob, be done just as well with the injected video.
As for not being able to tune anything in yet, ( this is most likely due to entropy, for it used to before )
After all electrolytics are replaced, and I have confirmed that the B+ on all the voltage dividers is OK, and tubes check OK, I will probably go over the whole thing end to end and measure tube voltages (K/G/P) .
which may, hopefully give clues to problem areas.

Well, that is not good... it looks like my AGC circuit is messed up.
No doubt its the reason I can't tune in anything...
https://imgur.com/a/NsW2dox
As far as I can see, R37 is the plate bias source, this circuit id a bit weird ) could also be leaky caps.. IDK.

Something is not right... 9v is way too low...
I am getting a very good strong horz pulse there though.
i will have more time to play with it this weekend.

The AGC circuit is a feedback circuit. This means that the 9 volts at the plate does not necessarily mean anything is wrong with the AGC circuit itself. It may be getting an incorrect detected video signal at the grid due to some other reason (like a dead IF) and trying to correct it by changing the AGC voltage. You need to check the detected video for starters. If it's missing, check and/or replace the AGC tube. And, you may be right that some component is bad. Check all the voltages in this area. Check resistor values wherever voltages are way off. Further trouble shooting could involve breaking the feedback loop by connecting an adjustable bias to the AGC line, as you would for aligning the IF. If video is missing or wrong amplitude and you can't get it by manually setting AGC bias, there is something dead in the IF or tuner.

Try wiggling the IF tubes. If the first IF gives pix noise and or sound noise then the problem is in the tuner if not it is in or before the lowest IF tube number that gives noise when wiggled. Another possibility is the AGC is missadjusted or broken....In that era of RCA the AGC checks the sync level in the video signal every horizontal pulse and adjusts the tuner and IF gain (by changing the grid bias of the tuner and IF tubes) to hold the video level constant.... the AGC control should be able to take the set from blank raster with no signal passing through to normal signal then on to excessive overdriven video that won't sync.... circuit failure can hold it in an exterme state.

I did try to “ wiggle” the IF tubes, and I did hear a crackle in the speaker as I did on all of them.
However, at this point, I have NOT been able to test any of the tubes yet, :( but I do know all bias voltage is there ( within 10% )
did a quick reading of plate voltage on ACG tube, did not match SAMS, ( as shown in other post )
suspect 1st if bias is not right as well, I'm prob stuck till I can get these RF tubes tested :/

OK, i think i found someone with a tube tester rather close by, I jst have not been able to get my hands on it yet. :(
Poking around the IF section, i did spot something a bit disturbing, https://imgur.com/hVmgorU

why is the bottom part of that NPO cap uncovered? did they not see that when they built it? It cant have been good to have that bit of its innards exposed all these years. :/

Looking a bit closer at the schematic ( just guessing ) that cap is a critical part , since it was a 5% and was part of the adjacent sound reject, so if it degraded because of being exposed and de-tuned the circuit... perhaps it may do what I'm seeing, not being able to tune in anything...

I've seen ceramics with that exposed bottom before...I believe it is probably done in the factory for a purpose.

If it doesn't leak current under voltage, and if reasonably close to rated capacitance it should be fine.

I saw many brand new ceramics like that when I worked at Zenith, that obviously met specs. Never had time to investigate why they were like that, but now I wonder if it was a way to tune them to within 5% in the capacitor factory by etching away some of the metal.
EDIT: or, of course, it could be unintentional but acceptable.

Disconnect and check that 150K and 180K resistors next to the 2nd IF tube, they're usually bad

I've seen ceramics with that exposed bottom before...I believe it is probably done in the factory for a purpose.

If it doesn't leak current under voltage, and if reasonably close to rated capacitance it should be fine.

There lies the headache, it's easy to check the value of a cap with any given digital meter, but leakage is tricky w/o a costly meter or some vintage tester, :/ unless, I go and build the circuit seen here... http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html
I do not intend to test electrolytic capacitors with it, so with 400v or more, if the cap under test is good, the reading for leakage should be 0...

Disconnect and check that 150K and 180K resistors next to the 2nd IF tube, they're usually bad

R48/r50...
yeah, i can see how that can mess things up, if they were bad.

As mentioned, I'm waiting till i hear from the guy here who has the tube tester, before I dive deeper into the IF section.

as a side note, i DO HEAR a audible POP, each time I change channel on the VHF, so SOMETHING is getting through.

So, I gather, tubes aside... that there is a higher probability that the old carbon core resistors could be out of tolerance than the ceramic disc caps, ( not that it can't be both :/ ) Which kinda makes sense, I had my Sansui 9090 go from working to non-working sitting in the same shed as the CTC, for a few years and had to replace several resistors on it to get it to come back up.

edit---
good thing to note, as I was poking around for info, I should stick with Carbon Composition Resistors if i do replace any, ( in the IF )
"Film Resistors-their frequency response is much worse due to the inductance and capacitance caused by the resistive path cut into the film." :o

40 mfd capacitors are available. Newark lists no fewer than 15 of them. I doubt the value is very critical.

The carbon comps are moisture sensitive...Storing them in a humid environment is pretty much the best way to force them to drift...Short of storing your set underwater.

The film types probably won't make a huge difference in the IF.

the carbon core ones i am seeing on Mouser are all 5% so I'm sure they will be better than the 10% that was in there.
And yes, it was stored in a shed outside, in central Texas, where it got as hot as 110f, cold as 18f and quite humid, but it was covered and protected.
So, with all that, I'll start with looking at the resistors in the If.

Oh yes, I definitely have some flaky resistors... I'm finding some wide open and others beyond 20% (some OK ) , will put some new ones in this weekend and see what happens.

The CTC16X is worth the effort. I had one and it made about the nicest picture of all my 60s'-era RCA sets, including a CTC38.

:dammit::dammit::dammit::dammit::dammit::dammit::d ammit::dammit:

Dammit dammit dammit!!!! BLOODY HELL!
Just when I get the IF section semi working..

I SEE snow on the screen ( with color ) I hear it in the speaker.

I go to hook something to tune in, click to the right channel, fine tune, I hear audio and POP, i lose raster...

WTF??.

quick check...

yes still have HV,, all tubes still lit, but something smells hot …

close look.
:saywhat:
i lost 970v boost... :(
https://imgur.com/fZYxnRF
https://imgur.com/ZNpZOcw
why did it have to choose THAT MOMENT to fry?!?

Check the caps that filter the boost for shorts also check the line for shorts (such as tin whiskers on pots, insulation breakdown and such). Something caused that resistor to burn up like that.

Also, it may be wise to get a new boost diode. I've seen them fail more than once and what killed that resistor may have damaged the diode too...Radio Shack carries a 2A 1.5KV PIV diode that if you place 2 in series makes for a really rugged boost rect. Failing that similar specked diodes off the net will work.

My first roundy I came at the problem from the opposite direction. After fighting to get HV, and having sound, but no raster and chasing voltages I finally found my cooked boost rect...The hilarious part was that aside from no color and shrunken raster from dying caps the darn thing worked great on varic power up for a few secs before dying, and I never retested tube damper after power-up so after driving my self batty trying to get HV for a couple of months, and giving up I found the problem robbing the tube for another working set that had an intermittent damper arc.

Check the caps that filter the boost for shorts also check the line for shorts (such as tin whiskers on pots, insulation breakdown and such). Something caused that resistor to burn up like that.

Also, it may be wise to get a new boost diode. I've seen them fail more than once and what killed that resistor may have damaged the diode too...Radio Shack carries a 2A 1.5KV PIV diode that if you place 2 in series makes for a really rugged boost rect. Failing that similar specked diodes off the net will work.

My first roundy I came at the problem from the opposite direction. After fighting to get HV, and having sound, but no raster and chasing voltages I finally found my cooked boost rect...The hilarious part was that aside from no color and shrunken raster from dying caps the darn thing worked great on varic power up for a few secs before dying, and I never retested tube damper after power-up so after driving my self batty trying to get HV for a couple of months, and giving up I found the problem robbing the tube for another working set that had an intermittent damper arc.


a tin whisker like https://imgur.com/eUeytX9 that.. :(
so i guess that pot is shot..

I'm not sure if I'm looking at a whisker too thin to see, a really fat whisker or a normal part of the pot rotor.


The pot is not necessarily dead. They can be serviced. Verify the short on the boost, unsolder the pot leads and verify the short in the pot...If short is still present (and not the fault of the pot being set to min or max) on disconnected pot then unmount the pot, pry the tabs from the back cover that wrap around the front up till you can take the metal back cover off, verify the whiskers and what they are growing from, sand the growth surface lightly with very fine sandpaper till whickers are gone and surface is clean and shiny, remove metal particles with contact cleaner double check resistances are normal and reassemble.

If disconnecting the pot does not show the pot shorted but boost is still shorted keep tracing that short on the boost line.

I'm not sure if I'm looking at a whisker too thin to see, a really fat whisker or a normal part of the pot rotor.


The pot is not necessarily dead. They can be serviced. Verify the short on the boost, unsolder the pot leads and verify the short in the pot...If short is still present (and not the fault of the pot being set to min or max) on disconnected pot then unmount the pot, pry the tabs from the back cover that wrap around the front up till you can take the metal back cover off, verify the whiskers and what they are growing from, sand the growth surface lightly with very fine sandpaper till whickers are gone and surface is clean and shiny, remove metal particles with contact cleaner double check resistances are normal and reassemble.

If disconnecting the pot does not show the pot shorted but boost is still shorted keep tracing that short on the boost line.

there is a really fat white strand on the blue screen pot, where the 970v hooks to it to the can of the pot that should NOT be there,,, hard to get a good pic with a cell cam :/

a tin whisker like https://imgur.com/eUeytX9 that.. :(
so i guess that pot is shot..


BTW, My very first exp with a roundie was when I was very young, I'm now sure it was a RCA, CTC-10A ( The Sullivan ), I remember the metal, gloss black lacquered cabinet. It was given to my parents by my grandparents, I loved that TV...
It later developed sync problems and my dad never really put the effort into fixing it and threw it away, I never forgave him for it, they bought a tiny RCA 19 inch hybrid to replace it.
So when I saw the chance to get this CTC-16xl years later... I took it!

You DID notice the brown cap with the crack in it hooked to the boost diode as well right?

You DID notice the brown cap with the crack in it hooked to the boost diode as well right?

Yeah, that maroon drop C140? does indeed look damaged. Don't discount those maroon drops as being reliable...While some are still doing okay several have reported finding them drifting in value or even leaking (I've certainly found at least one leaking current)...

Here is a possible cause of that resistor failing: C140 started leaking current badly overloading the boost rect diode causing it to short, the rect then passed ~1KV AC pulses to the boost line. The boost is resistively connected to the 400V B+ rail and on negative 1KV swings of the horizontal feeding the shorted boost diode it started passing too much current through that 100K resistor frying it. Should be easy to check by ohming out the rect in both directions and testing that cap.

Yeah, that diode and cap are toast..
its a bit hard to find replacements using part numbers from a 50+ year old list, ( the resistor is easy )
i have picked mouser # 80-PHE450SB4220JR06 for the cap, and 625-RGP25M-E3 for the diode, i should prob replace that big cap and the little .001s on the screen pots, but they are most likely OK

Yeah, that diode and cap are toast..
its a bit hard to find replacements using part numbers from a 50+ year old list, ( the resistor is easy )
i have picked mouser # 80-PHE450SB4220JR06 for the cap, and 625-RGP25M-E3 for the diode, i should prob replace that big cap and the little .001s on the screen pots, but they are most likely OK

These Panasonic caps are cheaper and a bit better for TV application (I use them in my resto work). https://www.mouser.com/ProductDetail/Panasonic/ECW-HA3C222JQ?qs=sGAEpiMZZMv1cc3ydrPrFw8Ry1bIy%252BUIP vQRZAQNzTU%3D

This diode has a faster recovery time and is better suited for rectifying horizontal rate AC, and also has higher reverse voltage rating (Which can save your bacon if the ~4KV DC focus ever arcs over to the adjacent screens that are driven from boost). https://www.mouser.com/ProductDetail/Vishay-Semiconductors/BY228-15TAP?qs=sGAEpiMZZMtbRapU8LlZD8CGBaOwn9wYNdIZOsoE% 252B4c%3D

This is what I would buy if I were looking to replace those parts in my set.

total, $13 :/ its costing me more in shipping than parts :(

gonna replace the .001s out of safety, also getting a 0.47uF in order to do the HOT cathode current test, ( did not have one )

While I wait for the parts ( coming tomorrow ) , there is something I've been wondering, on the schematic, (sams ) it refers to “spark gap” in a few places, like C155, but it is a normal cap, and not a spark gap capacitor, with slits in the top like I have seen before, but, they do have the leads of this cap routed in heavy stock cardboard, in what could be a spark gap configuration, is this what they mean perhaps?

While I wait for the parts ( coming tomorrow ) , there is something I've been wondering, on the schematic, (sams ) it refers to “spark gap” in a few places, like C155, but it is a normal cap, and not a spark gap capacitor, with slits in the top like I have seen before, but, they do have the leads of this cap routed in heavy stock cardboard, in what could be a spark gap configuration, is this what they mean perhaps?

Yup!

If you ever do a late 60's-mid 70's Zenith they use two pieces of magnet wire bound together with cloth shrink wrap. Anything (or rather any two things) conductive CAN be a spark gap if you want it to be, and there were plenty of things engineers tried to make them out of.

Boost voltage restored, I now know more than I did before.

I can almost get a pic locked in through the tuner, ( sound is OK ) pic is Horrid, and rolling horz. And there is NO COLOR via the tuner,( this may be partly due to the fact that i have 75 ohm hooked to 300, but unlikely ) this reflects the original problem with the set.
BUT if I tap in video at 1st video amp, I am able to get better sync lock and even some color lock ( a lot of barber polling)

This tells me the Original problem was most likely a messed up IF section.
I have not yet checked all the resistors in the IF yet,,, I stopped after I got a signal. I guess I have to check every one now.,,
but I'm not sure what I'll do w/o a known good Sweep Marker Generator...

Get the resistors in tolerance first...If you're lucky the alignment is fine and the only drift was resistor related.

A bit of confusion on the horz sweep ( cathode current ) adjustment.
The sams shows all these steps to do it... https://imgur.com/iZJm7bP
however, here this guy, ( who puts up very useful videos ) , did not show those steps, or omitted them.
Where they not needed and just skipped? Or done but not shown? I'm not sure what I'm seeing here, and if I should use that as guide for mine. ( also being RCA, same output tube )
https://www.youtube.com/watch?v=uBkSfc0aq8U

The video is showing the efficiency adjustment as an isolated procedure and assumes the other adjustments in the SAMS are nominal.

SAMS adjustments:
The first two, for "floating" H sync, are to set the H oscillator to free run at nominal frequency so the horizontal AFC and horizontal hold controls are centered and don't have to pull it one way or the other to an extreme degree. I'm not sure, but maybe being way off center could affect the horizontal drive waveform, which in turn would affect the output efficiency.

[video procedure goes here]

The measurement across R136 is actually across R146 in the SAMS schematic on ETF. This is the HV regulator cathode resistor. Caution, it is floating at about 400v. This adjustment is to check if the HV regulator range is more or less centered. If not, you are instructed to detune the efficiency coil to get more HV supply, but simultaneously not go beyond the horizontal output cathode current limit. Ideally you should be using two meters at once (if not, you need to go back and recheck the HO cathode current).

Finally, you are similarly instructed to detune the efficiency coil slightly if you see horizontal fold-over in the picture (and should recheck the HO cathode current just to be safe).

The video is showing the efficiency adjustment as an isolated procedure and assumes the other adjustments in the SAMS are nominal.

SAMS adjustments:
The first two, for "floating" H sync, are to set the H oscillator to free run at nominal frequency so the horizontal AFC and horizontal hold controls are centered and don't have to pull it one way or the other to an extreme degree. I'm not sure, but maybe being way off center could affect the horizontal drive waveform, which in turn would affect the output efficiency.

[video procedure goes here]

The measurement across R136 is actually across R146 in the SAMS schematic on ETF. This is the HV regulator cathode resistor. Caution, it is floating at about 400v. This adjustment is to check if the HV regulator range is more or less centered. If not, you are instructed to detune the efficiency coil to get more HV supply, but simultaneously not go beyond the horizontal output cathode current limit. Ideally you should be using two meters at once (if not, you need to go back and recheck the HO cathode current).

Finally, you are similarly instructed to detune the efficiency coil slightly if you see horizontal fold-over in the picture (and should recheck the HO cathode current just to be safe).

Actually, “r136” is correct for the CTC-16X series, close but not the same as CTC-16 ( sams 0818-2 vs 0736-4)
Close, but different enough to be confusing, :/
example 3rd IF on CTC-16 = 6EJ7 CTC-16X = 6JC6A, many other subtle diff.

The only reason that I brought it up is, that while I'm playing with it ( testing / turning it on) and such, I don't want to risk any stress on the flyback, since they are so hard to find a replacement for.
As it stands now, the FB looks to be in very good shape for it's age, with no wax drip ( well, just a tiny bit) below.

Interesting...
was just poking around parts lists, it seems that the CTC16 and 16x DO NOT have the same FBT :O

16= 113992 (906160-501) and 16x = 115843 (906160-502 ) or so says sams.

Not sure what the difference is :o


Edit--

I see it now.
VERY different,
16 has HV REC / FOCUS REC of 3a3 / 1v2 and 16x has 3ca3 / 2av2.
HV/Focus circuits are quite different.

Not that I have come across a bad one yet ( that I know of ) going over the SAMS, which I have been doing a lot of, in several key places there are VDRs, (voltage dependent resistors) and I can only find RCA part #s for them listed, and little if any reference to what values they may be ( cold/hot or voltage/amp range ) , so in anticipation that IF, any of these have to be changed at any point in the future, how does one find a correct modern value replacement?

Not that I have come across a bad one yet ( that I know of ) going over the SAMS, which I have been doing a lot of, in several key places there are VDRs, (voltage dependent resistors) and I can only find RCA part #s for them listed, and little if any reference to what values they may be ( cold/hot or voltage/amp range ) , so in anticipation that IF, any of these have to be changed at any point in the future, how does one find a correct modern value replacement?


I was wondering about this as well when I was checking out values earlier today. I thought about searching the rca part number and see if I could find anything.

I was wondering about this as well when I was checking out values earlier today. I thought about searching the rca part number and see if I could find anything.

As to WHY, they are there, ( just a guess) is that they keep things stable as the set warms up and voltages drift, so the owner does not have to keep getting up to adjust like the horz/vert hold.
But I don't think that what is in there, behaves like the more modern MOVs...

and thus may be hard to replace.

As to WHY, they are there, ( just a guess) is that they keep things stable as the set warms up and voltages drift, so the owner does not have to keep getting up to adjust like the horz/vert hold.
But I don't think that what is in there, behaves like the more modern MOVs...

and thus may be hard to replace.

Yeah that totally make since and they probably don't. I got the RCA copy of the schematic today. have not taken a close look at it yet, but I wonder if any info will be listed on it. though if there is I doubt its going to list what were looking for

I don't believe it.
I have started to try and check resistors in my set. (it sucks that most cant be tested in-circuit)
started checking and ran into trouble right at the start.
AGC line r36, 2.2 meg could not measure it with this cheap RS meter I have.. Off-scale high/ almost reads 20m on the 20m setting (no other higher) it cant be THAT far off :o

So it's
A: the cheap meter is lying to me and cant be trusted, or B: it really IS over 10x too high..
taking this resistor to work to check with a $400 fluke I have there.
Also getting another cheap autorange meter that goes up to 200m.

https://imgur.com/KHo8VmG

mine :o

Resistors tend to drift high (sometimes even open) and ones that start high tend to be worse so I tend to believe the meter...

Be GALD your set did not spend it's life outside getting rained on/in...I found a 1972 Sylvania in a ditch once with the amount of rust in its metal table model cabinet, rot in the back and lawn debris inside it I was sure the only good part would be the CRT...But then I washed the crap out and decided to 'play' with it. Somehow with little effort, it made a raster...Getting anything else out of it meant replacing 95% of the resistors in each stage (most were wildly out of tolerance). Somehow it made a damn good pic and decent sound for a while after re-resistoring it.

I just ordered an assortment of ½ watt metal film resistors (not carbon film, too high rfi ) Which should have most of what I find bad, I hope.
The resistor I tried to check last night checks at 31m , out of range of the cheap meter I had. :(
the new cheap meter coming goes up to 200m.
Someplace, somewhere, in my home is hiding a Fluke 73 III... :(
And I suspect that when I LEAST need it, is when it will crawl out of it's hiding place in the 6th dimension, where it has been the last 6 or more months and reappear.

https://imgur.com/KHo8VmG

mine :o

Nice looking chassis! looks to be in decent shape and not much rust or anything : D

I don't believe it.
I have started to try and check resistors in my set. (it sucks that most cant be tested in-circuit)
started checking and ran into trouble right at the start.
AGC line r36, 2.2 meg could not measure it with this cheap RS meter I have.. Off-scale high/ almost reads 20m on the 20m setting (no other higher) it cant be THAT far off :o

So it's
A: the cheap meter is lying to me and cant be trusted, or B: it really IS over 10x too high..
taking this resistor to work to check with a $400 fluke I have there.
Also getting another cheap autorange meter that goes up to 200m.

I have also ran into this myself a few time. I have had some resistors in a few of my old zenith radio sets that were meg omhs instead of low k's

also a while back I got this Klein meter, it isn't as nice as a 400 buck fluke, but its close. I love it a lot more than my old 20 dollar digital I had and it can test up to 1000vdc/vac and I have found that handy working on some of my old radios.

check it out, its just under 100 bucks

https://www.amazon.com/gp/product/B018CMKWSC/ref=oh_aui_search_asin_title?ie=UTF8&th=1

https://imgur.com/sob7yID
this is where my CTC spent the last 13 years or so,
and before that it was rented storage spaces, so it was always kept covered. :)

https://imgur.com/sob7yID
this is where my CTC spent the last 13 years or so,
and before that it was rented storage spaces, so it was always kept covered. :)

Nice! glad it was kept out of the weather

im looking forward to seeing pictures of your set when you have it running

SAMS makes it really hard to find R34,35,36 mounted on tuner :/
All they give is an overhead shot of the chassis / tuner ( page 17) with arrows pointing to a dark fuzzy low res area of where they are, no zoom of the area with the resistors marked :/

Have started on the sweep PCB. around the AGC/ sinc sep circuit.( takes a LONG time :O )
https://imgur.com/vKACCKZ

seems that 15% of the resistors are out of tol so far.

Keep this in mind when checking resistors. There is nothing that will make a resistor read high, other than a bad resistor. Any other parts of the circuit, ie: parallel paths, will cause a lower reading. I always check in circuit and if it is low then I remove it to check it. If it reads high, I just replace it. Since most resistors drift up in value, there is usually no need to take a resistor out of circuit for an initial test.

...Since most resistors drift up in value, there is usually no need to take a resistor out of circuit for an initial test.
There are occasions where a resistor will drift down if it's the older phenolic-encased type. If the resistor's been running hot for a long time, the phenolic case will gradually char from the inside and create a conductive path around the resistance element. Most often seen in one and two watt units.

i just wonder how critical i should be, i am seeing some WELL within the 20% range, and others just over /under and some WAY over. I tend to want to replace the ones not "well within range...

If you are looking at carbon composition resistors, you should know that the 5% ones and 10% ones often were picked out at the end of the production line, leaving the 20% ones always worse than +10% or -10% (a "bimodal" distribution).

Also if the 4th tolerance band exists; base the acceptable tolerance on that. Usually on 60's color sets the majority of resistors will be 10% silver bands with some 5% gold for critical apps and some 20% no-4th-band resistors thrown in non-critical areas for cost savings.

If a gold band checks within 10-20% but not in it's designed 5% and you leave it, then you just missed a failed component...

example, if i check a 560k res (10% tol ) and it checks at 617k, just outside of the 10% do I let it slide? or replace to be on the safe side?

using this site to tell me the max high / low for the tol for 10% and 20%

https://www.allaboutcircuits.com/tools/resistor-color-code-calculator/

so far, if has been close to the high or low side of failing i am replacing.

Your meter could easily be off much more than the difference between 616 and 617, so you should accept it as OK.

example, if i check a 560k res (10% tol ) and it checks at 617k, just outside of the 10% do I let it slide? or replace to be on the safe side?

using this site to tell me the max high / low for the tol for 10% and 20%

https://www.allaboutcircuits.com/tools/resistor-color-code-calculator/

so far, if has been close to the high or low side of failing i am replacing.

Ive been wondering the same thing as well. and so far if I come across one that is close or at the max, I figured it has drifted up this much may as well get it now than when it does drift out more causing a problem.

man I like that link btw! I've been doing color codes and tolerance by hand gah! lol

Ive been wondering the same thing as well. and so far if I come across one that is close or at the max, I figured it has drifted up this much may as well get it now than when it does drift out more causing a problem.

man I like that link btw! I've been doing color codes and tolerance by hand gah! lol

I'm thinking the same, After all, I got this box of brand new 2% resistors, and I DO measure them before I put them in.

I have 2 new digital meters, ( cheap ) I only got the 2nd one because the 1st did not have autorange and only went up as high as 20m, new one goes up to 200m.
Checking a removed resistor measures almost the same on both meters, ( less than 1-2% difference )
Also, when I take the removed resistors (after I replace them ) to work an tested with the high $$$ fluke, which is required to get calibrated every year, I get virtually the same results.
So, given that the set is over 50 years old, and that most resistors are of 10% or 20% how critical of an eye should on on for checking them to be on target?

If they are barely inside tolerance I leave them if the circuit works and change them if it doesn't... especially if it is something tuned that I rather try retuning by resistor than alignment...

Another out of the blue question, I have noticed that on the SAMS for the CTC-16xl, there is also a cathode current listing for the vert output, (38ma) , much like the listing for the horz, but can find no reference for testing it, is this something that does not even have to be looked at? As in its not as important as horz cathode current test and setup?

The vertical output transformers in most RCA roundy colors tend to be very robust and I can't recall any account of a restorer finding a bad one...VS flybacks that tend to be an above average failure point on RCAs....
If it we're a Zenith 25MC chassis or there about I say the fly you barely have to worry about but the vertical you want to watch.

In RCAs I regard the vertical current spec as a diagnostic tool for vertical problems rather than a needed adjustment...also if it is wrong you would either have to change components or adjust controls to points that may not give correct very sweep.

There's nothing wrong with checking the vertical in your set if you feel inclined.

I was just curious, like Rocket, I too am having problems getting full Vert height, but I have not really addressed that yet, I will after I can get color working through the IF.
I have just only NOW replaced the ugly c4 (50uf) that was on the sweep pcb, now under the pcb, cause I was working in the area as I was checking the AGC/ SYNC SEP area.

If they are barely inside tolerance I leave them if the circuit works and change them if it doesn't... especially if it is something tuned that I rather try retuning by resistor than alignment...

I wonder if that's what I did :scratch2:

I wonder if that's what I did :scratch2:


my fear is that once that I go through the IF board and check the resistors. that I will still have a IF problem...
and have no setup to align it with :(
As mentioned, I have no idea what was done to it before I got it T_T

yeah, I fear I may need to do an alignment also. I have not done one on a TV before and I don't have a sweep gen as well.

and speaking of that, I was going to ask you if your IF section has the shield on the underside? thought of it when I seen mine and was not sure if you were missing the bottom as well

yeah, I fear I may need to do an alignment also. I have not done one on a TV before and I don't have a sweep gen as well.

and speaking of that, I was going to ask you if your IF section has the shield on the underside? thought of it when I seen mine and was not sure if you were missing the bottom as well


Yes, I DO have that one, which I have removed for the time being , was not easy... took a LOT of heat! :o

Well that is some good news : D maybe they didn't mess around too much in there then

Well that is some good news : D maybe they didn't mess around too much in there then
well, if they messed with the coils, which are tuned from the top, who knows what kind of a mess they made :/

well, if they messed with the coils, which are tuned from the top, who knows what kind of a mess they made :/

yeah forgot the coils indeed :/

Yes, I DO have that one, which I have removed for the time being , was not easy... took a LOT of heat! :o

Sent out them templates to ya today ;D made a few extras also Incase one gets messed up

Sent out them templates to ya today ;D made a few extras also Incase one gets messed up


tks

I was thinking of making it out of something like...
this
http://tinyurl.com/y5eo2u9t

tks

I was thinking of making it out of something like...
this
http://tinyurl.com/y5eo2u9t

The original was thin sheet steel which you can get at ACE, Home Depot, and other places... Metal shears, files, drill bits and a stepped bit or chassis hole punch are all you need to duplicate most of it... the spring you'll have to get creative with.

Yeah np, and drill bit for the small holes and a step bit would be great for the larger ones indeed

:banana:my newly repaired TV pattern generator:yippy:
https://imgur.com/NpSGacg https://imgur.com/6rqrmoB https://imgur.com/2R9DUWh

which had 3 fried resistors, I think my dad did something stupid with it :/ ( he built it after all ) so I took a guess on the values :)

i now have an input source, other than an old VCR... :P

:banana:my newly repaired TV pattern generator:yippy:
https://imgur.com/NpSGacg https://imgur.com/6rqrmoB https://imgur.com/2R9DUWh

which had 3 fried resistors, I think my dad did something stupid with it :/ ( he built it after all ) so I took a guess on the values :)

i now have an input source, other than an old VCR... :P

:banana: that's pretty awesome!!

being tested after the latest round of resistor replacement. ( with repaired bar /dot )

https://imgur.com/dVAV4Yw https://imgur.com/MWQ3jYw

Also a shot with the chassis in " service " position :)

BTW: RCA color with separate tuner chassis tip: the tuner sub-chassis should have two half-moon tabs on it's chassis a distance away from everything that seem weird and pointless...Those tabs screw down to the main chassis (IIRC on either side of the interlock) securing the tuner to the main chassis in the factory recommended chassis out service position...

It took me a while to figure that out on mine and in the meantime that cables flexed so much that wires broke off tuner chassis terminals causing more work for me (the tuner IF coax was among the more annoying repeat breaks)...Don't follow my initial bad practice.

being tested after the latest round of resistor replacement. ( with repaired bar /dot )

https://imgur.com/dVAV4Yw https://imgur.com/MWQ3jYw

Also a shot with the chassis in " service " position :)

it even looks like we have the same cabinet! the harper from 1966 I believe.

Check out the 7th page down : D

http://www.bretl.com/tvarticles/documents/TVGuide1966BuyersGuide.pdf

hmmm maybe you actually have the Suffolk

hmmm maybe you actually have the Suffolk

yeah, that looks like it,

$500 in 1966 = $3600 now :o

yeah, that looks like it,

$500 in 1966 = $3600 now :o

Yeah! isn't that crazy! I think you could buy a car around 2k or so

OK... I get SLIGHT color rainbowing when i try to get the color bars to show up via tuner.
but I still DID get that blue color screen from the VCT to show on it when i injected video at 1st video amp. ( this was something I never did when I first got it, and falsely thought it was a bandpass failure )
this weekend will start to attack the IF section resistors.

Sent out them templates to ya today ;D made a few extras also Incase one gets messed up


they arrived today!! =^-^=

Waiiiii!

they arrived today!! =^-^=

Waiiiii!

Whoot! :banana:

So far, I am not finding much WAY out of tol resistor wise in the IF section. YET, i have just barely started though, did not have much time this weekend.

i may just run through the color AFC setup. sometime on it to see what happens.

I'm still a bit disturbed that the top cover was off of the IF section when I got it, and dread that someone was playing in it.
I CAN find Heathkit sweep marker generators out there, and there are books in how to make the probes and or so it says , calibrate them, but I have NEVER done something like it before. you can also find BK ones out there, but they are kind of useless w/o the probes and cables...

So far, I am not finding much WAY out of tol resistor wise in the IF section. YET, i have just barely started though, did not have much time this weekend.

i may just run through the color AFC setup. sometime on it to see what happens.

I'm still a bit disturbed that the top cover was off of the IF section when I got it, and dread that someone was playing in it.
I CAN find Heathkit sweep marker generators out there, and there are books in how to make the probes and or so it says , calibrate them, but I have NEVER done something like it before. you can also find BK ones out there, but they are kind of useless w/o the probes and cables...

hmmmm I wonder what happened to take out so many resistors? and it sure is possible that someone did monkey with all them pots. It will be interesting to see what happens when you get all the out of value parts replaced. Perhaps, could get lucky and someone didn't screw with it too bad and it could be work.

I really need to learn as well on using a sweep gen and how to do alignment, seems like it could be a fun journey

I'm going from pure speculation here, based on what I have looked up and seen around, and so on.
The IF alignment, sets up the general response curve of the “front end” of the TV, and the marker generator is a tool to help set that up. And when out of tune, color is prob the first thing lost, much like a FM tuner that's borked, mono works, but you just can't get MPX stereo to work, no matter how hard you try to turn the fine tuning knob...
But as I said, just an educated guess. :)

I'm going from pure speculation here, based on what I have looked up and seen around, and so on.
The IF alignment, sets up the general response curve of the “front end” of the TV, and the marker generator is a tool to help set that up. And when out of tune, color is prob the first thing lost, much like a FM tuner that's borked, mono works, but you just can't get MPX stereo to work, no matter how hard you try to turn the fine tuning knob...
But as I said, just an educated guess. :)

Not quite that simple. It is possible to have good sound, color, and monochrome with bad alignment they will all be at different points on the fine tuning, and if one is good the others will suck...can also loose one all together or have one or more that is never good.

Basically the sweep gen gives a flat input at all frequencies the IF can process and the marker gives narrow pips above that so you can identify key points of interest in that span... the IF changes the output level based on iti frequency response.

What's confusing me is, when I look at manuals for marker generators for both Heathkit and BK, and see , typical color tv IF response curve with markers added, they look pretty much the same in both, but have different marker points ( mhz wise ) in the positions shown on the SAMS procedure refrence Fig, 1
I'm not sure what this means, if anything...

There were 2 IF frequencies in the US 21MHz(older non-UHF sets) and 44MHz (UHF, color and pretty much everything after 1960). Markers and response would vary a bit depending on the RF/IF design and the type of TV.

You can actually get a digital synthisized sin generator or an analog one and a digital frequency counter and have your own custom adjustable marker...IIRC some generators had provisions for extra crystals so the user could add fixed marker frequencies.

Video alignment is one of the few things I've never done in TV repair(but have studied to someday do). I've only had around 3 sets that genuinely needed it to function, and a few more that could have benefited from an alignment.

Audio and color you can often sort of fudge without all the gear and procedure... though some would disagree.

Hey Yamamaya, I think my service/normal switch has been rewired, 3 of the 4 pins were cut from the switch. If you have any spare time next time your chassis is out, may I trouble you for a picture of how that switch is wired?

https://imgur.com/byHBeuB
https://imgur.com/lF885FA

hard to make anything out but.. here

:D

https://imgur.com/byHBeuB
https://imgur.com/lF885FA

hard to make anything out but.. here

:D

Thanks for the pictures! :banana:

It looks like a jumper was added between the left and middle terminal and possibly a resistor between the right and middle terminal

This is what mine looks like

Thanks for the pictures! :banana:

It looks like a jumper was added between the left and middle terminal and possibly a resistor between the right and middle terminal

This is what mine looks like

That make absolutely no sense whatsoever, I can't see how it can work that way... the white wire, should go to point 48 as shown on the SAMS, ( it does on mine ) and gets grounded when in service, this kills vert sweep, this is same in both 16 and 16xl.
The B side of the switch is a bit harder to understand, but looks like it is lowering the video drive on the cathodes in service position, or adjusting the voltage slightly, it is doing SOMTHING via l16, not sure, but I have no idea how your switch has been wired,,, :o

From what I can see, and it's hard to tell, but it seems they someone has removed S5 entirely from the circuit , and permanently wired it into “normal” position wiring, but I can NOT understand why anyone in their right state of mind would do such a thing.

Radio Shack up till they vanished sold that style of switch... pretty sure they are still in production just gotta track down a source, drill out the rivets, and bolt N solder a new one in...

...and permanently wired it into “normal” position wiring, but I can NOT understand why anyone in their right state of mind would do such a thing.
The switch was probably flaky and that was their fix for it. The whole purpose of the service switch was to facilitate purity and grey scale adjustments. But those can be done without the switch. Just takes a tad longer.

https://www.mouser.com/ProductDetail/CW-Industries/GF-1126-0033?qs=sGAEpiMZZMtHXLepoqNyVXvKblAm878lJknN1bMNho A%3D

easy to find, they are everywhere..

Thats great I will get that switch from mousers!

then to figure out how to get it wired right.. : /

Its hard to tell in the picture, but the switch looks burnt and the back left corner a chunk is missing of the switch. Only wire left connected on the switch is the white wire. the rest was snipped off from what I can tell, then this modification was made.

Seriously can't believe I didn't see this until recently

I tried to do color AFC setup and could not...
went WAY out into the weird zone when i tried...
something is really strange with the burst amp
Sams says to ground this pin , and so on...
before i go grounding anything, I want t make sure I have the right pin and that things look OK, that is where things went wrong.
Sams says 40v
I measured over 160v:tears:
something aint right!
https://imgur.com/YNdvFez
i was clipped to the leg of r10 ( it checked ok )
v22 is new, r163 seems OK, but i did not check it out of circuit.
i have not had much time to poke around it yet, but i'm not sure why the cathode voltage is so high :yikes:
and i'm not about to short it to gnd until i see it in normal range... so I can't do the color AFC setup yet. :dunno:

? Did you make a typo? Where is R10?

? Did you make a typo? Where is R10?

R10 is the 1 meg color killer pot.

OK, this just got a whole lot weirder... I seems whoever worked on this before me, ( the jerk who removed the cover off the IF board and lost it & REMOVED the color PCB... ) noticed the problem with the burst amp, and tried to fix it... because when I checked r163 and r144, they have already been replaced with metal film 2%, so I'm still in the dark as to why the cathode v is so high....

Rocket. if you ever get a chance, with your chassis in service position, and a good stable color pic, can you measure all the voltages on R10 ( color killer pot ) Sams says they should be 30 ish in voltage

OK, this just got a whole lot weirder... I seems whoever worked on this before me, ( the jerk who removed the cover off the IF board and lost it & REMOVED the color PCB... ) noticed the problem with the burst amp, and tried to fix it... because when I checked r163 and r144, they have already been replaced with metal film 2%, so I'm still in the dark as to why the cathode v is so high....

Rocket. if you ever get a chance, with your chassis in service position, and a good stable color pic, can you measure all the voltages on R10 ( color killer pot ) Sams says they should be 30 ish in voltage

Yeah sure thing, I actually plan on throwing the chassis in for a test run tomorrow to check and see how its performing after replacing a few caps. : D

OK, this just got a whole lot weirder... I seems whoever worked on this before me, ( the jerk who removed the cover off the IF board and lost it & REMOVED the color PCB... ) noticed the problem with the burst amp, and tried to fix it... because when I checked r163 and r144, they have already been replaced with metal film 2%, so I'm still in the dark as to why the cathode v is so high....

Rocket. if you ever get a chance, with your chassis in service position, and a good stable color pic, can you measure all the voltages on R10 ( color killer pot ) Sams says they should be 30 ish in voltage

Got them measurements while running with good color picture.
measured color killer pot, 3 terminals. 1st term closest to power supply side of chassis is 53.1, mid term 1.184, 3rd term 33.70 :thmbsp:

If I have learned anything over the years, its never underestimate the stupidity of those who came before you.
Poking around the color pcb I have seen that most all resistors have been changed, with what looks like 1 watt carbon film, it calls for ½, and this is no problem really. I'm using ½ metal film, you can see the 2 new one I just put in in the pic, they ALSO replaced some caps, cause some disc one look new, and the person who did it, does not know how to shape leads correctly cause I see a lot of cracked meniscus, a big NO NO in my line of work, but THEN I SEE what is shown in the pic, problem with c96, and no doubt causing my voltage problem... WTF? Very careless...
https://imgur.com/YTsHAxc

Rocket, your readings are right where they should be, thanks! :D

Awesome! and no prob :D

Well, putting that cap in did not help, cathode voltage is still high, 135v where sams says 40v.
I'm not sure how this burst amp circuit works.
Do I ignore the fact that I see the high V on there a try to run the color AFC anyway ? Good chance it wont work.
I DO See the waveform on grid 1 as shown on sams, it looks like the lower one for color, and never changers, no matter what is on screen. 150V should be 50v horz rate Way too high I'm being flooded with horz freq?



any idea what may be doing this? I do see lines to the FBT, for what I assume is horz pulses.

I suspect either V22 has a short or it has a DC bias voltage issue.

I suspect either V22 has a short or it has a DC bias voltage issue.

i got it "new"

i guess i can try another

What is the voltage on pin 2 of v22? Have you changed the cathode bypass capacitor, and the screen capacitor c98 and c99? Have you checked the 255 volt source? Don't rule out a bad tube, even if it is new. Check the resistors 163 and 144 out of circuit. What about c94?

What is the voltage on pin 2 of v22? Have you changed the cathode bypass capacitor, and the screen capacitor c98 and c99? Have you checked the 255 volt source? Don't rule out a bad tube, even if it is new. Check the resistors 163 and 144 out of circuit. What about c94?


All resistors have been replaced before i got it wit carbon film, and just to be safe i replaced 163 and 144 again,

who ever had this before me did a lot of weird stuff to it.
I do not think c98 and c99 have been replaced, they still look old.
all bias voltage is OK, checked them when i replaced the electrolytics
I have ordered a new tube anyway.

another potential problem
I don't know if its related to the burst amp and color killer circuit problem or the is even more problems,,,

looked at c22 ( hooked to output of 1st video amp ) feeds chroma bandpass , and good signal on the 1st video amp side, nada on the other. could be that CK is just not working right with the burst amp borked and clamping down, or its a sign of another problem :/

Here is where things are now...
The set it pretty much in the shape as when I first got it. ( after undoing the color PCB being out ).
No color, sometimes barber-pole effect seen, unknown if it's IF related, (evidence of work done in IF PCB )
ALL resistors replaced on color PCB , except for higher power ones, some disc caps new, not sure of any else.
Apparent burst amp / color kill problem , which I am assuming is shutting off chroma bandpass, ( if I understand the circuit ) .
No video signal seen out of c22, feeding l24 ( bandpass coil ) . Saw suggestion in other thread to short point E, to force on, not tried yet.

Cathode voltage of burst amp too high, (V22) not sure why yet, all resistors new, tube “new” (another ordered) voltage starts at 20v when first turned on, and jumps to about 130v when horz kicks in.
plate/g2 voltage OK, was unable to measure g1 voltage with DVM, due to strong waveform on it ( gonna have to get my analog meter cleaned and working ) .

New, ( relatively ) v22 6JC6 coming fri, & a set of HV disc caps come mid-week, will replace c95,98,99,100 and re-test this weekend.
I hope this does something... but it may not, there may be problems elsewhere, as mentioned, I still don't fully understand this circuit yet, it seems to be a balanced feedback setup, but that is a guess.

The barber polling is probably weak color getting through. The chroma osc if not adjusted perfect will loose sync on weaker color signals, but sync to strong ones.

I believe I have found an error in the Sams for the CTC-16, (surprise surprise ) this is present on both the 16 and 16x versions. (sams 818-2 & 736-4 ) .

If you were to look at the waveforms on the input to G1 on the burst amp on both, one is marked for color input ( square symbol ) but It shows no video information between the pulses, the one above does.
I have checked the sams for the CTC-15 & CTC-20, and they are opposite of what is shown here.
Video information is seen on the lower waveform ( marked for color ) and none on the one above, somehow they are backwards on both CTC-16 schematics.
To me it has always made more sense for it to be the other way around, thus I was looking at other schematics.

this is what has me confused...
Am i reading too much into it? an just go with is on the sams?
https://imgur.com/g4gMKmr ctc-16x
https://imgur.com/KsYqFI8 ctc-20
https://imgur.com/fDhZQ3W ctc-16


EDIT...
I'm still disturbed as to why that wave on G1 was so high, this may be the cause of everything, overpowering any video trying to get in, source is FBT pin 7, also goes to conv socket , pin 8, where it's shown to be at 270v , when I get the cap set in, add to check list, c94, c97, r145, r146, ( did they put a wrong part in? )
There has to be some reason that the horz pluses going in are so high that the Amps can't work.

Yamamaya42, what kind of meter are you using to measure the DC on the cathode? Could it be the pulse waveform is fooling it?

Another way to measure DC on a pulse waveform, with a scope:
1) set the scope for AC and center the waveform vertically within the screen.
2) note the level of any convenient point of the waveform
3) change the scope setting to DC
4) note the CHANGE in voltage of your picked waveform point (the DIFFERENCE between the reading in AC mode and DC mode) - this is the actual DC (average of the waveform)

Yamamaya42, what kind of meter are you using to measure the DC on the cathode? Could it be the pulse waveform is fooling it?

Another way to measure DC on a pulse waveform, with a scope:
1) set the scope for AC and center the waveform vertically within the screen.
2) note the level of any convenient point of the waveform
3) change the scope setting to DC
4) note the CHANGE in voltage of your picked waveform point (the DIFFERENCE between the reading in AC mode and DC mode) - this is the actual DC (average of the waveform)

I thought of that, and I looked for a waveform on the cathode and there was none, even with the o-scope turned down to 500mv, but for some reason I'm seeing a wave of over 150 in G1, which I don't think is right at all.

I plan on re-testing with a analog volt meter later, but something tells me that horz wave is too high , for some reason SHOULD BE 50v max, and they made a mistake someplace when they were putting new stuff in before i had it.

oops - I got confused where you are seeing a waveform and where DC.

oops - I got confused where you are seeing a waveform and where DC.

I just checked it,, there IS a 10v sawtooth on the cathode, its prob related to the massive wave being fed into g1, hopefully I can work out what is causing this all :/

The pulse on G1 seems to come from a 3:1 voltage divider consisting of R145 (100k) and R144 (47K). I would check that the values are correct and R144 is not open / disconnected from ground.

Do yourself a favor and resolder ALL of the points where that circuit board solders to the chassis. These are used for ground connections and will cause all kinds of strange problems. Use a higher wattage iron so you can get enough heat on the chassis stake.

Do yourself a favor and resolder ALL of the points where that circuit board solders to the chassis. These are used for ground connections and will cause all kinds of strange problems. Use a higher wattage iron so you can get enough heat on the chassis stake.

As i mentioned earlier in the thread, some fool REMOVED this PCB, and I replaced it when i got it, so they have already been re soldered.
the handy weller 8200 i got from my dad did nicely for soldering the gnd points :p

Scope each end of R144 directly. You should see the 150 v pulse on one end if it's connected to G1. You should see zero on the other end if it's actually grounded.

If you see zero on both ends or 150 v pulse on both ends, one end or the other is not connected.

Scope each end of R144 directly. You should see the 150 v pulse on one end if it's connected to G1. You should see zero on the other end if it's actually grounded.

If you see zero on both ends or 150 v pulse on both ends, one end or the other is not connected.

I will check that this weekend, tks, I replaced r144 & r163 last weekend, cause i suspected something, I will check more of the carbon film ones that were put in this weekend, esp r145, when i replace some of the disc caps that look like they have not been replaced yet.

decided to take a quick look a r145...
looks again , eyes pop out of head...
$%$%$^#$%#$!!! F%^%!!!
screams and swears in a very unladylike manner
:yikes::wtf::mad:
https://imgur.com/82LmbdD

that is NOT 100k!!
brown blk orange??
no wonder everything is messed up...
how many other resistors did they get wrong.. :cry:

decided to take a quick look a r145...
looks again , eyes pop out of head...
$%$%$^#$%#$!!! F%^%!!!
screams and swears in a very unladylike manner
:yikes::wtf::mad:
https://imgur.com/82LmbdD

that is NOT 100k!!
brown blk orange??
no wonder everything is messed up...
how many other resistors did they get wrong.. :cry:

Stupid mistakes: even smart people can make them.

I spun my wheels on something stupid on the Silvertone CTC-15 I restored as my first roundy and my first color set that genuinely needed a resto to work...The thing had a shrinking monochrome raster when I powered it on a variac so I recapped it and then it had no HV. I went over the horizontal for well over a month, gave up, then needed to borrow the damper for another set I needed to take pics of for a college project...Then I realized the damper which had been fine on the first power up and initial tube testing had shorted after I recapped it...Then suddenly with a good damper inplace I was chugging through the resto again.

Shows your humanity. Now you're trustworthy. You're now Sherlock Holmes!

i'm going to have to go over the whole PCB now and check all the res they put in now, knowing this, I should never have assumed they did it right when I saw that the Resistors had been changed T_T.

Hot damn! :banana:

did a quick change of r145 to the right value, and cathode voltage of Burst amp is right on target! 41v.

Will go over the PCB this weekend for other wrong resistors, and attempt color AFC setup again! :thmbsp:

Woohoo! Fortunately you found it. Unfortunately you will have to be suspicious of everything the previous guy touched.

Awesome!!
Cant wait to see this set running : D

Sucks the last guy screwed up so much on this set and will have to be suspicious of everything. However it will be pretty rewarding when you get this thing running :)

Latest status
Still unable to to preform Color AFC Setup.

Only able to see barber pole effect. ( still may be IF related, unknown )
BW pic is very stable.
Cathode v on burst amp is now at 40v, where it should be, but seeing a 10v saw tooth wave there, not sure if this is normal.

Not finished going over PCB for other errors yet.. :(
evidence that L24 ( bandpass coil ) may have been replaced.

STILL getting no scopeable video on the far ( badpass ) side of C22, it also looks to have been replaced. Removing v17, killer / chroma bandpass tube makes no change in this, but lifting the far side of the cap does.
This situation was first spotted years ago when I got the set.

Will have to try and dig deeper ( find other errors ) to work out why it's dong this,
From what I understand, and how this all works, if NOTHING is getting past C22, or its getting distorted somehow, there is nothing for the Burst amp and bandpass to work with, and thus the color osc can't lock on and so on...

I should see SOMETHING on both sides of C22, right?

If the chroma osc is too far off freq it won't sync even with ideal sync input/synch circuit performance.

Sync or not you first need to get it to the point where you can tune the osc to not have many barber Pole lines but what looks like continuous to tint drift... once you get that if there's any life in the chroma sync it should be able to lock.

If the chroma osc is too far off freq it won't sync even with ideal sync input/synch circuit performance.

Sync or not you first need to get it to the point where you can tune the osc to not have many barber Pole lines but what looks like continuous to tint drift... once you get that if there's any life in the chroma sync it should be able to lock.

but i'm not sure I'm getting anything for it to lock onto.
I'm seeing nothing at the bandpass coil even wit the tube removed ( same tube has the color killer )
there are no pules at all v23 chroma phase detect.

what should i be seeing at point 80 ( v17 removed )? I'm seeing nothing but noise, no video, the overpowering horz pulse that was there is gone, but, no video, so i suspect there is an error someplace that i have not found yet . :(

Sawtooth on cathode is normal.

Back of envelope without using exponentials: Average current is 1 ma (40v/39kohms). This is supplied in a narrow pulse of, say 2.5 microseconds, or 1/20 of the horizontal rate. So, the peak current is 20 ma for 2.5 microseconds, = 50 nanocoulombs. This causes a rise of 5 volts on 10 nF C98.

Copied from “no color on CTC-16” thread, almost exactly like mine.

Posted by Old TV Nut.
So, go back to grounding point E. This should defeat the color killer and let the bandpass amp conduct. Turn the color control all the way up and see if you see any color.

As far as using the scope, set the scope sweep rate to horizontal sweep rate (about 10 microseconds per division). For starters, set the vertical sensitivity to 10 volts per division (or 1 volt if you have a 10X probe) and check for presence of all the waveforms shown in the SAMS schematic for the chroma sync phase detector and color killer, plus the chroma bandpass. Set the vertical to higher gain to view the smaller waveforms that are marked about 10 or 12 volts peak to peak.

Do you have a color bar test pattern to use, or are you using some program video? The chroma waveform on pin 3 of coil A14 will generally not be as big and obvious with program material as with a test pattern, but you should be able to see it come and go when the color killer operates.


This is most likely the source of my problems now, As when Point E is grounded, I get absolutely nothing at g1 of u17 ,even at 200mv, I just see noise , nor is there any signals at chroma phase detector,
but the ref Osc is running, I can see that, not sure what freq.

I do see the horz pulse at g1 of the burst amp, but it still never changes with the video on screen, even though that r145 is correct.
What I don't know (or understand yet ) is something so messed up in this circuit that won't allow video into it through c22 (from 1st video amp) for any of the color to work correctly ? Could IF section be so out of wack that it is not letting any color through for the circuit to work with? A combo of both perhaps?

OK, update...
After spending nearly 2 hours checking every resistor that was replaced on the color PCB, I found one more that was wrong, R170 has a 10k in it where it should be 27k ( so says SAMS ).
Other than a lot of crappy lead shaping and sloppy solder work, the other resistors are OK. ( I have a very critical eye for lead shaping and solder form, this comes from my many years in the industrial electronics field ) .
There are a few caps that still look old, that I will most likely change this weekend.
However, I really doubt that this will fix the problems, for I'm pretty sure that the putz who did this messed with the IF section and I have no real way to align it.

So once I am done checking the color PCB, I will try again to tap in video at the 1st video amp, this time lift up one end of l9, and try color setup with external video, this MAY cause a problem because composite video is 1v PtP and the wave shown at that point is 3.5, I may have to build a small video amp, or it may not care.

I have pretty much confirmed it now, this putz has made a mess of this set, and it will be very hard to set right.
The IF is messed up and wont pass color, any that does get through, is so weak that the color circuits cant process it. Any color seen via the the tuner is so faint ( seen as barber-poling) you can hardily see it on the screen.
I have found and fixed 4 mistakes on the color PCB , so I can only assume that when they first tried to fix this and did not notice/ check their work they then turned their attention to the IF pcb , and made things worse, gave up, then donated this TV to the place where I found it . :(

When I try to insert direct video at the 1st amp, I get a MUCH stronger color signal to the color circuits and very pronounced color barber-poling on the screen, but I'm still unable to do the color afc setup that way because the sync/ afc is unstable, this is most likely due to that I'm feeding feeding in composite video ( 1v p2p) at a point where it should be 3.5.
dvd input
https://imgur.com/IMh054m

So now I have few options, try to find a way to get the IF un-messed up ( aligned ) so the color setup can be done correctly, or try a video amp and hope it stabilizes things enough to let me do color setup.

https://imgur.com/m0IePGv
With 3rd video IF removed & composite taped in to 1st video amp. ( lead clipped to TP1 @ L9 )
I have checked resistors on the IF and found very few out of tolerance, and my chances of finding anyone local with the equipment and knowledge to align it is pretty much zero, my only chance is to try to build the video amp for it.
You can see the stark difference black levels with input via tuner in the last post and this one, so it is very much needed.

https://imgur.com/m0IePGv
With 3rd video IF removed & composite taped in to 1st video amp. ( lead clipped to TP1 @ L9 )
I have checked resistors on the IF and found very few out of tolerance, and my chances of finding anyone local with the equipment and knowledge to align it is pretty much zero, my only chance is to try to build the video amp for it.
You can see the stark difference black levels with input via tuner in the last post and this one, so it is very much needed.

That screen cap has enough color info that you should be easily able to achieve synchronized color with adjustment of the chroma osc/osc control.

You may not be able to lock the color at this point, but you could try the procedure to the point where you have oscillator frequency adjustment zero-beating with incoming chroma.

You may not be able to lock the color at this point, but you could try the procedure to the point where you have oscillator frequency adjustment zero-beating with incoming chroma.

I tried, w/o much success, as you can see, I don't even have a strong enough video input for the blanking amp to work T_T.
But, after an hour searching online, I think I just may have found what I need!
:banana:
http://www.next.gr/uploads/113/Simple-video-amplifier-circuit-diagram.png

will it work? only one way to find out!

edit
I'm also looking at the lm359 op amp option.

I still can't decide which amp to go with, on the one side, the simple 2 transistor amp is cheap and easy, and SAYS it will boost to 3v ptp, but I'm a little worried that it also shows the output being at 4v dc, where the g1 voltage of the 1st video amp is 0v, I don't know if this will matter to the TV or not.
On the other hand, the lm359 , much more costly and complex,will take a bit to work out the programmable gain to get 3.5 v ptp out of it.

T_T
choices... choices...

I still can't decide which amp to go with, on the one side, the simple 2 transistor amp is cheap and easy, and SAYS it will boost to 3v ptp, but I'm a little worried that it also shows the output being at 4v dc, where the g1 voltage of the 1st video amp is 0v, I don't know if this will matter to the TV or not.
On the other hand, the lm359 , much more costly and complex,will take a bit to work out the programmable gain to get 3.5 v ptp out of it.

T_T
choices... choices...

Why not just use a .1uF cap to couple the transistor amp output to the grid?..It will block DC from changing grid bias, should couple the video just fine and RCA colors all had some form of DC restoration that negates and need for DC video coupling in the early stages of the video chain.

simple 2 transistor amp was a failure, :thumbsdn:
spent a whole evening building it, but I'm getting very little gain out of it, not enough for what I need.

https://imgur.com/xYoNZOY

gonna have to try the op-amp version, and see if i get better gain out of it.

Can you give us a schematic of where you are connecting it in the set? If the amp is built right it should give the specified gain, but maybe not if you connect it to a point that loads it down.

Can you give us a schematic of where you are connecting it in the set? If the amp is built right it should give the specified gain, but maybe not if you connect it to a point that loads it down.


I did not even attempt to hook it up, I looked at the wave on the scope and it was hardly 1.2v ptp out, unhooked to anything.
the goal is to have it hooked to Point B ( L9 ) test point one.
And i DID recheck the work, It just dud not put out 3v ptp

I think you should go back and check all the DC voltages on your amp. I have used this general design before and it worked. Then if you increase R7 to 470 ohms you should get a gain of 4x instead of 3x.

Could you have mixed up leads on your transistors?

Could you have mixed up leads on your transistors?

Ditto. I did that on a magnetic tape preamp once. The transistor type had a reverse lead arrangement instead of the usual EBC sequence. As a result, all the stages were using the emitter as the collector and vice-versa. Instead of three stages with a total gain of 1000, I had three stages with a total gain of 3.

Another thing: I looked at that diagram and calculated the currents from the resistor voltages, and it looks like R5 must be 330 ohms, not 220, to get those voltages. Actually, I think it wouldn't hurt to increase R5 somewhat more than that, so that a larger proportion of the output current is supplied by T2.

One more thing - make sure you didn't read the omega symbol as a zero somewhere. The diagram is fuzzy. R7 is 330 ohms, not 3300, for example.

problem found, checking the DC voltages found that the cheap 12v power supply that i THOUGHT was regulated, is not. it says,"12v 100 ma " but hooked up, I was getting 16.5.
I hooked it up to adjustable pws and am getting much better results.

I'll just have to add a 7812 to the pcb to make it really stable.
thanks for everyone's help so far :)

output of V2 of the simple 2 transistor video amp, ( 7812 added )

https://imgur.com/xlQdL9t

output is through .1 uf,
will see how it works this weekend, I may have to up the gain a bit like old TV nut said, We shall see! :)

:thmbsp:

My only question is, once this is set up for perm, how should it be done? Directly TO g1 ( pin 7) of 1st video amp? ( L9 removed ) or through L9 to g1 with point 20 disconnected ?

L9 may be an IF choke, or it may be a peaking coil to match the detector to the grid capacitance, I don't know. Either way, it is not needed with the low output impedance of your amplifier. Plus, since your amplifier is a feedback circuit, hanging odd impedances on the output could pose a slight risk of high frequency oscillations. So, remove L9 and go through a coupling cap and then directly to G1, I think.

Note: my fingers stumbled all over my reply, I think I got it fixed up now, but reread it in case you saw the jumbled version.

Duh.. I think I'm awake today... If you use a coupling cap and remove L9, you will need to add a grid bias resistor (say, 100k) from G1 to ground.

Now I'm going to go out on a limb here, I assume the only real reason that they said use a color bar input for the color AFC setup is that they wanted a stable non-moving color picture input to work with, and back then, the color bars were the best choice?
So that in this age, it can be also done with a DVD input on pause?

Now I'm going to go out on a limb here, I assume the only real reason that they said use a color bar input for the color AFC setup is that they wanted a stable non-moving color picture input to work with, and back then, the color bars were the best choice?
So that in this age, it can be also done with a DVD input on pause?

Correct. Even a DVD on play. But it's easier to see what you're doing when the screen is full of bright color.

Correct. Even a DVD on play. But it's easier to see what you're doing when the screen is full of bright color.


This is why i made the " Lost In Space" DVD, cause season had the extremely loud color in the outfits :)

getting closer :)

https://imgur.com/Tvyc044
not quite there yet :(
following the setup did not get me anywhere after a couple tries, so I tried what most say NEVER to do, and that was eyeballing it.

Now that is this close, I will try to run through the setup instructions again and see what happens.

Still not able to get clean color w/o barber-poling, will try the color AFC setup later, in a few weeks once back from recovery from surgery ( Ugh! ), but I'm not holding my breath, as I mentioned earlier in the thread, I see evidence that L24 & L25 have been replaced, and they even look new, so chances are the chroma bandpass is messed up also, and I'm not aware of a way to align it w/o a sweep marker generator. Unless there is some way that I don't know of.

Your picture looks like you're getting enough chroma amplitude. If that's correct, you should also be getting enough burst to lock up the phase detector. In that case, you should not try re-aligning the bandpass first but should look for a problem in the burst gate, burst phase detector, or reactance circuit first.

Good luck with your surgery!

ODD, I went and got a cheap DVM that had a freq meter built in and hooked it up to l33, and it reads 34.8 meg hz at that point. Now the meter can be way off, ( unlikely ) or the ref osc is not at the freq that it needs to be, I have not checked the caps around the area yet to see if they are correct, new. Old or replaced with wrong parts, the crystal is the orig, from what I have seen, and I'm not sure what one to replace it with, it that is what is needed, 3.58 vs 3.579545Mhz ( you can get either ) and not sure what capacitance rating for the CTC-16xl :/

It being off freq might be the source of my problem with not being able to do the AFC setup.
I have a list of caps to get , but I won't be able to do it for about 2 weeks or so.:sigh:

ODD, I went and got a cheap DVM that had a freq meter built in and hooked it up to l33, and it reads 34.8 meg hz at that point. Now the meter can be way off, ( unlikely ) or the ref osc is not at the freq that it needs to be, I have not checked the caps around the area yet to see if they are correct, new. Old or replaced with wrong parts, the crystal is the orig, from what I have seen, and I'm not sure what one to replace it with, it that is what is needed, 3.58 vs 3.579545Mhz ( you can get either ) and not sure what capacitance rating for the CTC-16xl :/

It being off freq might be the source of my problem with not being able to do the AFC setup.
I have a list of caps to get , but I won't be able to do it for about 2 weeks or so.:sigh:

Given the barberpoling pictures I've seen you post I'm fairly certain your meter is giving you an incorrect reading. If the waveform is not a linear sine wave it is easy for a digital counter to register some multiple of the true freq.

If you have an oscilloscope I'd use that to check the freq if I got a reading that out there.

Given the barberpoling pictures I've seen you post I'm fairly certain your meter is giving you an incorrect reading. If the waveform is not a linear sine wave it is easy for a digital counter to register some multiple of the true freq.

If you have an oscilloscope I'd use that to check the freq if I got a reading that out there.

https://imgur.com/SZOb74Z
https://imgur.com/DQml4WL
the sign wave is very stable, it's here that I wish i had the digital o-scope that I use at work, which has Freq readings.
I know ( have read how to find freq on an analog scope) , but I am very bad with numbers...
i really cant tell with any detail what freq that is :/

edit.
I can't SEE any drift of the sign wave via the scope, it does not mean there is none, my scope is not been calibrated since i got it, but its a very good one, so i trust it. I nearly wet myself when I looked up the value. (Tektronix 7934 Mainframe only − 2019 value: $29,370)
I guess Like I mentioned, I will start with the caps, but I have heard from sources that the crystal can be suspect, but I don't know to what degree.

ODD, I went and got a cheap DVM that had a freq meter built in and hooked it up to l33, and it reads 34.8 meg hz at that point. Now the meter can be way off, ( unlikely ) or the ref osc is not at the freq that it needs to be, I have not checked the caps around the area yet to see if they are correct, new. Old or replaced with wrong parts, the crystal is the orig, from what I have seen, and I'm not sure what one to replace it with, it that is what is needed, 3.58 vs 3.579545Mhz ( you can get either ) and not sure what capacitance rating for the CTC-16xl :/

It being off freq might be the source of my problem with not being able to do the AFC setup.
I have a list of caps to get , but I won't be able to do it for about 2 weeks or so.:sigh:

1) From the picture, you are only off by 3 or 4 cycles per 60 Hz, or 180 to 240 Hz. You should be able to adjust L31 (A16) to go through zero beat and be off either way, from a few hundred Hz too low to a few hundred Hz too high. Can that be done? If so, the system should pull in when you get close to zero beat. If it doesn't, the problem is in the phase detector or reactance tube circuit, not the oscillator. If you cannot go THROUGH zero beat to be off either way, there is a problem in the oscilator circuit.

2) I hope you meant your meter reads 3.48 MHz, not 34.8 Mhz, but even that is very wrong and does not correspond with the number of rainbow bands you are seeing. Forget the meter.

3) A 3.58 MHz crystal and a 3.579545 are the same thing, just stamped with fewer digits. The one you wouldn't want would be 3.56 or 3.59, which would be used in a gated rainbow generator, not a TV.

1) From the picture, you are only off by 3 or 4 cycles per 60 Hz, or 180 to 240 Hz. You should be able to adjust L31 (A16) to go through zero beat and be off either way, from a few hundred Hz too low to a few hundred Hz too high. Can that be done? If so, the system should pull in when you get close to zero beat. If it doesn't, the problem is in the phase detector or reactance tube circuit, not the oscillator. If you cannot go THROUGH zero beat to be off either way, there is a problem in the oscilator circuit.

2) I hope you meant your meter reads 3.48 MHz, not 34.8 Mhz, but even that is very wrong and does not correspond with the number of rainbow bands you are seeing. Forget the meter.

3) A 3.58 MHz crystal and a 3.579545 are the same thing, just stamped with fewer digits. The one you wouldn't want would be 3.56 or 3.59, which would be used in a gated rainbow generator, not a TV.

correct, it WAS 3.48 MHz that the meter displayed :p oops
and i did try adjusting L31 (A16) and it did not seem to have any effect that I could see on the scope.
I will try again once I go over all the caps. i have already checked all resistors, found 2 wrong.

correct, it WAS 3.48 MHz that the meter displayed :p oops
and i did try adjusting L31 (A16) and it did not seem to have any effect that I could see on the scope.
I will try again once I go over all the caps. i have already checked all resistors, found 2 wrong.

You will not see any effect on the scope - a few hundred Hz is not a visible percent of 3.58 Mhz. Determine if you are having an effect by looking at the picture and the number of rainbow stripes you see.

You will not see any effect on the scope - a few hundred Hz is not a visible percent of 3.58 Mhz. Determine if you are having an effect by looking at the picture and the number of rainbow stripes you see.

That it did, :)

just to clear things,

I understand " phase detector " v23 and related, bur I'm not sure what is meant by "reactance tube circuit" :)

It's the triode section of V24, labeled "Chroma Reference Oscillator Control." Sorry I did not use the schematic name. It's also called a reactance tube, because it amplifies the reactance of C111, 4 pf, by the gain of the tube, due to connecting C111 from plate to grid. Any stray capacitance between the grid and the plate is also amplified in a triode, and is referred to as Miller capacitance. Anyway, the purpose of this circuit is to vary the capacitance attached to the oscillator circuit according to the control voltage developed by the phase detector. It varies the capacitance when the control voltage from the phase detector varies the gain of the triode.

The phase-locked loop works this way: the phase detector develops a voltage depending on the relative phase (and frequency, within limits) of the oscillator and burst. If the oscillator is tending to be too high in frequency, the control voltage will increase the gain of the control tube, thus increasing the capacitance loading the crystal, and reducing its frequency, and vice versa. L31 is tuned to get as close to the right frequency as possible when the detector output is zero; then it can correct either way as things drift with temperature or other factors. That is why you short point J to ground when adjusting A16 for zero beat - you are making the control voltage zero.

It's the triode section of V24, labeled "Chroma Reference Oscillator Control." Sorry I did not use the schematic name. It's also called a reactance tube, because it amplifies the reactance of C111, 4 pf, by the gain of the tube, due to connecting C111 from plate to grid. Any stray capacitance between the grid and the plate is also amplified in a triode, and is referred to as Miller capacitance. Anyway, the purpose of this circuit is to vary the capacitance attached to the oscillator circuit according to the control voltage developed by the phase detector. It varies the capacitance when the control voltage from the phase detector varies the gain of the triode.

The phase-locked loop works this way: the phase detector develops a voltage depending on the relative phase (and frequency, within limits) of the oscillator and burst. If the oscillator is tending to be too high in frequency, the control voltage will increase the gain of the control tube, thus increasing the capacitance loading the crystal, and reducing its frequency, and vice versa. L31 is tuned to get as close to the right frequency as possible when the detector output is zero; then it can correct either way as things drift with temperature or other factors. That is why you short point J to ground when adjusting A16 for zero beat - you are making the control voltage zero.

that it what I thought, all the related caps for it are on my hit list, if it said 10% i'm getting 5% if it said 5% i'm getting 2% and so on, and making sure if is says NPO that I'm putting new NPO ones in.
and the ones with no tol listed I'm putting in 10%
a bit of an overkill perhaps, but they are cheap.

Surgery went OK, took forever, spent more time laying around waiting than anything. got there at 9am, left at 3:30. :(
Now I wait till I can move w/o hitting the ceiling T_T

List of caps ordered (mouser)
75-564R60GAQ10 10pf NPO
594-D331G47U2JH63J5R 330PF
594-S221K25Y5PP63K5R 220pf
75-561R10TCCQ82 82pf NPO
75-562R10TSS10 .01uf
75-561R10TCCV39 3.9pf NPO
810-CC45SL3JD150JYNA 15pf
594-S104Z93Z5VL83L0R .1uf
598-CD15CD070DO3F 7pf

should have them next week, used slowest shipping, no use in spending $7 for ups ground, just to have them get here sat an sit and wait, Mouser is so close to me anyway, they will prob be here Monday via USPS basic ship anyway.

prob won't put them in and test till the weekend of the 8th. :D

suggestions:

Since the ceramic disc caps are unlikely to be failures, do some more troubleshooting before all the effort of replacing everything.

Make sure you cannot go through zero beat by adjusting A31/L16 with point J grounded. If you can get zero beat, there is no problem with the oscillator.

If you can get zero beat with J grounded, unground it and observe what happens. If the oscillator frequency changes only slightly, then look at point J with your scope and a voltmeter to see if the beat frequency appears coming out of the phase detector, with an average value about zero. If you now tune A31/L16, you should see the beat frequency change on the scope. If you get very close to zero beat, the DC voltmeter will start to follow the slow voltage swings of the detector output. If you see the detector output behaving normally , the phase detector is OK, otherwise it is suspect. So, if the detector output is OK and the oscillator is OK, and you still have no lock, that points to the control (reactance tube) circuit.

as mentioned before, i have no idea what was done to it before I got it, every resistor in the color pcb was replaced ( 2 with wrong values ) which now is correct, there is a VERY HIGH CHANCE that who ever did that also replaced caps, this is why I'm going over it like this.

You're right, I wasn't considering the perversity of the previous "fixer," but if you could identify the current cap values and try replacing only the obviously wrong ones first, you might save some effort.

suggestions:

Since the ceramic disc caps are unlikely to be failures, do some more troubleshooting before all the effort of replacing everything.

Make sure you cannot go through zero beat by adjusting A31/L16 with point J grounded. If you can get zero beat, there is no problem with the oscillator.

If you can get zero beat with J grounded, unground it and observe what happens. If the oscillator frequency changes only slightly, then look at point J with your scope and a voltmeter to see if the beat frequency appears coming out of the phase detector, with an average value about zero. If you now tune A31/L16, you should see the beat frequency change on the scope. If you get very close to zero beat, the DC voltmeter will start to follow the slow voltage swings of the detector output. If you see the detector output behaving normally , the phase detector is OK, otherwise it is suspect. So, if the detector output is OK and the oscillator is OK, and you still have no lock, that points to the control (reactance tube) circuit.

I now have the caps I ordered, not had a chance to go over things to check / replace things yet, spent most last week resting, will try this weekend, I understand MOST of what you said to check, but the term “zero beat” is new to me, and I really am not sure how to apply it to the situation at hand. T_T
(looking it up did not help much )
PLZ forgive if it seems silly to ask, but, I grew up mostly in the digital/ solid state age, tubes were already way out when I was in the Electronics class in HS, “zero beat” may have been covered, perhaps, I may have just forgotten :/

The rainbow stripes are at a frequency that is the difference between the color burst frequency and the color oscillator in the TV. This difference is a "beat frequency." The term comes originally from sound and musical instrument tuning.

As you tune the color oscillator, you will see the beat frequency change, visible as the number of rainbow stripes. As you get closer to zero difference between the burst and the oscillator, the number of stripes will decrease and they will get broader. If you get close to zero beat (meaning the oscillator frequency is close to the burst frequency), the phase lock loop should pull in and stabilize the color, but if the detector or control circuit aren't operating, it will be unstable, and you will see the hue of the whole image change randomly. As you continue tuning the oscillator from too high to too low (or vice-versa), the number of stripes will increase again.

So, with point J grounded, there is no control voltage, and you should be able to tune the oscillator from too low to too high (or vice-versa) with zero beat somewhere in the middle.

With point J ungrounded, if the phase detector is working, a scope will show a sine wave at the beat frequency (of a couple hundred Hz or less) at point J. This corresponds to the rainbow stripes of color phase you see in the picture, because the oscillator frequency is off from the burst frequency by this much.

I looked for a good illustration on YouTube, but couldn't find one, so I hope my verbal description is understandable.

The term "beat frequency" has its origins in acoustics. When two sound waves are of different frequency, they 'beat' against each other, producing a third (or intermediate) note which is the difference between the two. But if the two are identical in frequency and phase, there is "zero beat".

The same thing occurs with RF signals. The beat is sometimes called a heterodyne, as in superheterodyne receivers; the incoming signal 'beats' with a local oscillator, producing the intermediate frequency (or IF) signal which is then amplified and demodulated.

The term "beat frequency" has its origins in acoustics. When two sound waves are of different frequency, they 'beat' against each other, producing a third (or intermediate) note which is the difference between the two. But if the two are identical in frequency and phase, there is "zero beat".

The same thing occurs with RF signals. The beat is sometimes called a heterodyne, as in superheterodyne receivers; the incoming signal 'beats' with a local oscillator, producing the intermediate frequency (or IF) signal which is then amplified and demodulated.


Now that I sort of remember from classes, :p when we were thought AM/FM stuff, but that was sooo long ago :) I was a dumb teen then, a lot of that info on my master hard drive was flushed long ago to make room for other data! :p

this won't be until the very LAST stages, but this does look perfect for a replacement the focus rect, does it not? https://www.electronicsurplus.com/nte-electronics-inc-nte118-diode-selenium-rectifier

or am I seeing it wrong.?

something is not right :/

c101,102,103,104
c98,99,100 now new.
still cant do color afc.

https://imgur.com/ZL7DFjY pin 3 of v23 (removed) phase det
https://imgur.com/IsFfC3h pin 1 of v23 (removed) phase det
https://imgur.com/rb81uJO pin 1 of v23 (tube in) phase det -did not bother with pic of pin 3 with tube in.

https://imgur.com/QuIObvz point J
not sure what i should be seeing there, but I don't think that looks right.

Edit,
What you said about " the number of stripes will decrease and they will get broader. If you get close to zero beat (meaning the oscillator frequency is close to the burst frequency),"
an am not seeing this, They roll up,/down but tuning the coil for the osc, never made them decrease/ get broader, they did stop moving at one point...

which makes me suspect it's off freq. ( a guess )
so when i saw this...
https://www.ebay.com/itm/RCA-CTC-15-part-105330-3-58-mhz-color-crystal-NIP/143245169998?hash=item215a13d54e:g:oBYAAOSwrHtcUie 2
it was too good to pass up,
it may not fix anything... or, who knows...

Point J is the filtered phase detector output, so what you're looking for there is the few hundred Hz (at most) sine wave indicating how far off frequency you are. this is like a fairly low audio frequency tone, so, set the scope horizontal rate much slower, say 1 or 2 milliseconds per division.

pins 1 and 3 of the phase detector should have the gated burst, and that seems to be what you have, so it's OK. Pin 2 should have the continuous wave at 3.58 MHz from the oscillator. The schematic says 10 volts p-p - the copy is not clear if there is any pulse waveform or beat note waveform superimposed or just pure sine wave.

Yes, it is possible the crystal is bad, but I was under the impression that when the crystal dies the oscillator stops in these sets, and you definitely have the oscillator running

Rolling up or down shows that you are changing the frequency, but if you can't get it to slow down to zero beat with point J grounded, there is something wrong in the oscillator (or maybe control) circuit. The caps you replaced would not be critical unless completely dead or very wrong values. Look for trouble with the cap values in the oscillator and control circuits.

C112, C118, C114, C111, C108. Due to C108, there should be no 3.58 MHz energy whatsoever at point J, only the low frequency beat note.

I will start hitting that area this weekend, meanwhile, I took the removed caps to work and checked them with a calibrated capacitor tester , it does not test leakage :( , but this is the result.

c98 .01 = .005
c99 .01 = .013
c100 .001 = .001
c101 330pf = 298pf
c102 330pf = 342pf
c103 330pf = 351 pf
c104 330pf = 339 pf
I prob did not have to replace some of them, :/ but ya can't test them in circuit, and I can't sneak this tester home! :p

Rolling up or down shows that you are changing the frequency, but if you can't get it to slow down to zero beat with point J grounded, there is something wrong in the oscillator (or maybe control) circuit. The caps you replaced would not be critical unless completely dead or very wrong values. Look for trouble with the cap values in the oscillator and control circuits.

C112, C118, C114, C111, C108. Due to C108, there should be no 3.58 MHz energy whatsoever at point J, only the low frequency beat note.

I can see what you mean with C108, high freq filter, not sure what C109 does with it, orange drop through r167, as I mentioned, I intend to go over them this weekend.
As you can see above, c98 was WAY out of tolerance (low) for 20% C99 just barely inside (high)
C100 OK , C101-104 2 within , 2 out of tol for %5...
I just hope that this won't be the same for all caps in the set :(

C108, R167, and C109 in combination with the output impedance of the phase detector (two 1 Megohm resistors in parallel) form a classic phase lock loop filter. At frequencies below 48 Hz (the combination of R167 and C109), the frequency response is rolling off from 1.0 at DC to 1/15 above 48 Hz (33k/500k). The response is flat up to about 480 Hz (the combination of R167 and C108) and rolls off again for frequencies above 480 Hz.

The bandwidth and transient response of the closed loop (and the amount of phase error due to frequency drift with temperature) is also very much dependent on the loop gain, which involves three factors: the gain of the phase detector (volts per radian); the gain of the control tube (picofarads per volt); and the gain of the oscillator response (radians per second per picofarad). [radians per second = 2 times pi times Hz]

To design this circuit, you would measure/design the gains for each of these stages individually, and calculate the RC filter values to give the desired frequency and transient response (damping factor).

just an " out there " question, the Sams says r164/r165 as matched pair, same with 149/150, right now, the person who worked on it before me has 5% carbon film ones in there, i only checked by looking that they were correct value, how critical is the " matched pair" ? should I bother replacing them with 1% metal film ones I have ( checking that they are as close as they can be to each other via a calibrated VOM ) or just leave it as it is now with the 5% ones in? i have no idea if this person checked for them to be a " match " or not, or does it not really matter with 5%?

Looking at the photo of the color board, it appears the original resistors were carbon composition. I think these could change value by a couple of percent due to heat of soldering, subsequent moisture absorption, etc. even if initially matched. However, it's hard to guess what they had in mind since they don't tell you.

If you just throw in 5% tolerance resistors, the center voltage could vary by as much as +/- 1 volt (because there is 40 volts across them), so that must be too much, since unmatched resistors are not allowed here. 1% resistors would cut this down to +/- 0.2 volts, which certainly must be close enough, since this is about the closest tolerance you could achieve with an analog ohmmeter anyway. Since carbon comp resistors probably would not hold such a tight tolerance, my guess is that somewhere in between, like a 2% match, is OK.

If this were a professional monitor circuit, it likely would have a pot between the two fixed resistors, with a procedure for zeroing the output voltage under certain test conditions.

By the way, it lools to me like DC is blocked everywhere in the phase detector circuit, so you could measure these two resistors without unsoldering them.

No such luck with the color killer detector, because of the DC path through R147.

Looking at the photo of the color board, it appears the original resistors were carbon composition. I think these could change value by a couple of percent due to heat of soldering, subsequent moisture absorption, etc. even if initially matched. However, it's hard to guess what they had in mind since they don't tell you.

If you just throw in 5% tolerance resistors, the center voltage could vary by as much as +/- 1 volt (because there is 40 volts across them), so that must be too much, since unmatched resistors are not allowed here. 1% resistors would cut this down to +/- 0.2 volts, which certainly must be close enough, since this is about the closest tolerance you could achieve with an analog ohmmeter anyway. Since carbon comp resistors probably would not hold such a tight tolerance, my guess is that somewhere in between, like a 2% match, is OK.

If this were a professional monitor circuit, it likely would have a pot between the two fixed resistors, with a procedure for zeroing the output voltage under certain test conditions.

I will most likely just put the 1% ones in that I have, to be on the safe side. You can get .5%, but that's prob overkill for this situation.
mouser # 71-CMF551M0000DHR6
And even though they are 4 hours from me, It cost more to ship it than the parts themselves, not worth it. :p

Set color killer control fully CCW, set Tint control to center of it's range.
-notes killer in full off setting to be set later, Tint mid range to be calibrated later.

Connect color bar generator to ant inputs, adjust for normal color reception. Short pin 1 of Burst Amp, V22 to gnd.

notes, suggestion of color bar generator was for non-changing stable input, and any paused video from DVD or the like can be used, or else levels will change as video moves, changes, Shorting of burst amp pin 1 is to be sure no killer input is going to it & it is in fully on state. Easy access to pin 1 via killer pot R10.

Connect DC probe of volt meter to pin 1 of phase detector through a 470k resistor. (V23)
adjust A15 for max deflection ( most voltage ? ) if no reading, osc is not running, adjust A16 to start, & retry. Remove short from pin 1 of burst amp, adjust A17 for max deflection on meter, make sure osc is running and locked in.

notes , Phase detector looks to be isolated , via the 330 pf caps and fed pulses from L30, so I assume the 470k resistor is used to not load it down when doing this setup, I did see the voltage peak when adjusting A15 & A17 , but no kind of “lock” per-sey, just different degrees of barber poling when the short was removed from the burst amp, but it DID have some visual effect when removed.

Short point J to GND, remove meter from prev step, adjust A16 until color bars stand still or drift slowly. Remove short from point J , check to see that color bars sync with low input signal. Retouch A16 for best hold as needed.

notes, I tried this step, even though I was never able to get any sort of “lock/hold” as mentioned in the step before, and no adjustment of A16 was able to get a hold, just as mentioned above, varying degrees of barber poling.
I have not gone on to the last steps, obviously.

I did see healthy pulses into the phase det, ( shown in prev entry ) , and at point J, a sign-wave, at 1 ms per division on the scope, but could also see noise at higher scan rates, ( not sure if that's normal or not, prob is. )

I am still not done going over the osc / osc-cont area yet cap wise, not really found much yet, but SOMETHING, is not right, cause with the fed in video, going through that AFC set up, I should have been able to get a lock of some sort by now.

And as I mentioned, I know for sure that L24 & L25 were replaced before I got this thing, and never really adjusted as far as I can tell, but as mentioned a while back, this is not related to my current headache, and just hope it does not come back to bite later...

At this point it would be helpful if you had an accurate frequency counter and could measure the range of adjustment with L31 (A16) to verify that you are always on the low side or high side and cannot get nominal frequency. It seems that there must be something wrong with the oscillator circuit (wrong capacitor value or such).
C112, C118, or C114 would be prime suspects, or even one of the .01 bypasses (C110, C113), since you say the board was mangled by whoever had it last.

At this point it would be helpful if you had an accurate frequency counter and could measure the range of adjustment with L31 (A16) to verify that you are always on the low side or high side and cannot get nominal frequency. It seems that there must be something wrong with the oscillator circuit (wrong capacitor value or such).
C112, C118, or C114 would be prime suspects, or even one of the .01 bypasses (C110, C113), since you say the board was mangled by whoever had it last.

all I have is the freq counter in the meter I bought, and its only 4 digits, I can try to get one with a few more. but they may be costly. by this weekend i will have gone over the whole circuit.
That guy turns out, did NOT have a new xtal, and ended refunding me :( so if on the odd chance it is bad, I'm not sure what to replace it with.
The bottom of the pcb has white flux residue all over it, not sure WTF type of solder / flux was used, and it is a bitch to get off, but i got a lot off around the osc area, i have no idea if it was causing problems, bit it is ugly..

One of these should work:
https://www.ebay.com/itm/10-x-3-579545-3-58-MHz-QUARTZ-CRYSTAL-ECS-35-17-1-HC49-U-17pF-COLOR-BURST-NOS/123784629370?_trkparms=ispr%3D1&hash=item1cd2238c7a:g:09kAAOSwrslaZjcK&enc=AQADAAAB4KX%2FKt4E1xf3SDqEdBclaYZBCntCqLpML%2F AJ%2BYJZTOSsn0c0g%2B%2FyN%2BSlTcD8mm1TDh%2FS%2BA7M 9erVz214jArCr1Oi0mkJ4JTjwmCEOlJWlh6t8%2Bmnzoc%2BNG rG0Xx%2FTSHVbpMaRSBxt5r7%2B3gHyx1%2BQSFb1QuiD0MVw8 wlbSipgewB%2BI184G7D9FnLCtPscHUUn2OrEH%2FZTC4PqOu% 2Bt4YsDYx7vEoH1w%2FJ5O8p2STMrLqjiYb5WORjIYmSmG9DlE %2FR8vVI%2FLEiRXWUtzUVfCvaNt9ZL8cf1KBp6vADXXwCZMQL r0eSmV69iLHxEeM7Qgp3ZjNiYpDGg%2Bi2hywIYiW9qqaDiiOY 2aZavUcrE1bhoDHvkbC%2F8TVF9GIduMqr%2FsVCOUS%2FUkxY AYB0zJOk5kiLAek8qLz6u9mwq9asn%2BMAZetXJUh44JWCMsqc lcTp4CZsqgSOofrJ8lrUKdhTEp3GiGu0VaGPJ15iTfD23YgTr3 ckSUtu1zamD8SvmCkTftDlYW8pcZNCP1RPmrXIMgMYPOpH4tuA 3a72WMF4c8XjFv7IJ8yeU0lAQhwKvLxFuMJs8zOpDVUuudR9A3 zAHb61LmmucgRzzrOlcygDtuMTcxDlDvRWhz5lQqpxkHpESWCn QA%3D%3D&checksum=123784629370e600405cd4b54496b0b441d273ffe 97e#shpCntId

What have you tried to remove the flux?

isopropyl alcohol 99, Chemtronics ES835B , and a remover for water base flux,

what ever was used, it is very hard to get off.
I can tell, that the untouched parts of the set have OLD rma flux on them still.

this i almost never used any more in production, but was used a lot back then.

we use water soluble and no-clean,( lead free) I had to get special order leaded rma solder to work on this.

when the resistors were replaced, some unknown type of solder was used, and the flux mix caused a white scale that has to be almost scraped off, not alcohol or Chemtronics would really soften it much, I gave it a good try and got some off but was afraid of damaging things.

17 pF on the crystal? that narrows things down a lot ( so may options looking them up :o )
i assume Mouser #: 520-HCA357-17X is the same?

Actually, I think Zenith used 17 pf, and RCA used something larger, like 22 pf. So search on ebay to see if you can find something like that. But if not, I think the ones cut for 17 will work with a slightly different tuning of A16. The important thing is that the crystal sees the equivalent of the capacitance it is cut for as the result of everything that is attached to it. Crystals tuned for one or the other will change the gain of the control stage, which will affect the pull-in range and transient response to some extent.

Mouser has crystals @ both 20pf and 30pf.
I don't know for sure that the original is bad, but I don't know that it's good either.
I do know it's oscillating, but something seems to be off with the circuit.
If I understand things correctly, with point J grounded, I should be able to hook a frequency counter to L33 ( general area ) and be able to adjust L31 (A16) to get 3.579545 mhz, and as well as a respectable range above and below.

I wonder if the door knob who worked on it before you used something like acid core plumbing solder?... You're never supposed to use that on electronics but some people did, infact if you go back to the 20s and 30s some electronics makers used it.

I wonder if the door knob who worked on it before you used something like acid core plumbing solder?... You're never supposed to use that on electronics but some people did, infact if you go back to the 20s and 30s some electronics makers used it.

Not a clue :( , I just know that what is left behind is white scale, hard and crusty, and I can also see that the replaced resistors did not have the lead protrusion clipped off on the bottom but were broken off by stress, ( I can see the copper in the center ) , this is probably not a big deal in this case, but such a thing is a big no-no in my line of work, and violates iso standards in every way. :(

Mouser has crystals @ both 20pf and 30pf.
I don't know for sure that the original is bad, but I don't know that it's good either.
I do know it's oscillating, but something seems to be off with the circuit.
If I understand things correctly, with point J grounded, I should be able to hook a frequency counter to L33 ( general area ) and be able to adjust L31 (A16) to get 3.579545 mhz, and as well as a respectable range above and below.

20 pf version should be fine.

The fact that it's oscillating and the frequency doesn't go all over the place as you adjust it would indicate that the crystal is working.

from a pic of the bottom I took when Rocket wanted to see how my switches were wired,
https://i.imgur.com/lF885FA.jpg
if you look very close, you can see the krud :/

So far, replacing caps has not helped :(
https://imgur.com/uodtlrG
almost all caps in the OSC circuit new, point J grounded, this is as close to 3.579545 i can get.
not sure what else to try other than replacing the carbon film-resistors that were put in there with 1% metal film.
The crystal IS OK. removed and tested in x-tal tester, it was on freq.
and got a really neat pic with crystal removed, all reds were green, there was color lock, so burst amp and related circuits are working. not sure what else to look at other than the resistors that were put in before i got it, I only checked visually they they were right value. 5% carbon film in there now.

...got a really neat pic with crystal removed, all reds were green, there was color lock, so burst amp and related circuits are working.
Does the 'green' turn down when you turn the color control down? If so, the osc is not running. What you're seeing is the chroma amplitude without the 3.58 phase-reference signal.

So far, replacing caps has not helped :(
https://imgur.com/uodtlrG
almost all caps in the OSC circuit new, point J grounded, this is as close to 3.579545 i can get.
not sure what else to try other than replacing the carbon film-resistors that were put in there with 1% metal film.
The crystal IS OK. removed and tested in x-tal tester, it was on freq.
and got a really neat pic with crystal removed, all reds were green, there was color lock, so burst amp and related circuits are working. not sure what else to look at other than the resistors that were put in before i got it, I only checked visually they they were right value. 5% carbon film in there now.

Hard to believe you're off that much with the crystal in place (800 KHz low!), especially since the crystal tests to be the right frequency on a crystal meter. I suspect your frequency meter is reading really off. If the frequency were this far off, you would have fine rainbow stripes that might not even be visible.

Also agree that the green without the crystal is an indication that the oscillator is not running.

More sleuthing needed. Dumb question, but do you have any scope probes, meters, jumper wires, or etc. attached when you are trying to tune the oscillator frequency? Which caps in the oscillator circuit are NOT new?

https://imgur.com/9HcgQcz

pic with crystal unhooked
when i took the readings with that meter, both times, there was nothing hooked to the set but the meter shown in the post hooked to L33.
right now c120 and 123 are not new, as they are under the can of L32 and i really did not want to remove it if i did not have to.

C120 and C123 should not affect oscillator frequency, so I think no worries there.

Does L31 measure 8 ohms, as the schematic says?

How far have you turned the core of L31 when you try to tune it? Do you think you could remove it completely without breaking it? (Trying to find out if you are always on the low side of 3.58 Mhz).

How far have you turned the core of L31 when you try to tune it? Do you think you could remove it completely without breaking it? (Trying to find out if you are always on the low side of 3.58 Mhz).

That is the one thing I have not checked yet, The resistance check of L31, and I am able to tune the core all the way from as low as it will go to where i can sii it poking out the top, i did not go any higher, i could have, but saw very little change on the meter.
i will check the resistance of it when i replace the 5% resistors with 1% in the area, i got a huge box of them of most common values, so it wont be much of a problem to change them.

the larger ones, 1w are most likely OK anyway

OPEN COIL!!

it read 12 ohms
had to operate on it to get it to 8 ohms.
and then..
https://imgur.com/MNNx88t
https://imgur.com/CqMWDXJ

:banana::nutz:

Looks good!

It is probably time to fix the cataract and adjust the greyscale to be less blue.

Looks good!

It is probably time to fix the cataract and adjust the greyscale to be less blue.

color level is changing slightly perhaps I need to re tweak A15 & A17 now that I can get lock?

or could this be a symptom of the a symptom of the new coils in bandpass never being adjusted?

At this point, i don't even have the Convergence assembly on the neck, its plugged in but I made no attempt to set output levels , or adjust anything, spent all this time trying to get color, now on to next things, i guess!

If your color control is set too high that may be causing fluctuation. In tube sets, if you overdrive the chroma it will get noisy and flickery.

Perhaps I should try 1 more time now to get color via the tuner/IF section, but from what I saw in the past, I won't get my hopes up. :(

another thing noticed, when injecting video like I am now, I get retrace lines, that i'm pretty sure i did not see with input via the tuner.
perhaps I need to tweak the input amp gain up a tad. IDK :o

as expected, no color via the tuner/if. no surprise there .

and I did see things correctly, retrace lines much less notable with tuner input, so I will have to set the gain on the amp a wee bit higher I think.

I just tweaked the video amp a bit, replaced R7 with a 750 ohm trimpot, so i was able to up the gain a bit and it looks fantastic now, color is VERY stable, and black levels are OK.

next thing to work on is the damn cataract , I am also seeing the same problem with vert that Rocket described, so I guess I must replace some caps there to get full field, I also got to set up audio injection as well, but i do not see that being that hard.
I am also seriously thinking of getting a solid state HV rectifier for it to lower the load on the FBT.

Just a wild guess, a good point for audio injection is point 30, V7 & V8 ,no longer needed, should probably remove C53, but not 100 % if that's needed .

I will also try to get full vert height this weekend, following in Rocket's footsteps.

I'm still waiting for a really hot summer weekend, where I can have a friend help with the cataract repair, it's really too big / bulky for me to do on my own, and I do not want a repeat of the 25###22 incident when I was in electronics class, one second the CRT was there in front of me, the next, it was gone...

I found one!!
https://imgur.com/M8K151C

:banana:

Should have it next Week!

https://imgur.com/GYwbedU

WOO-HOO!

:D

I now have full screen!
:thmbsp::guitar:
Audio input DOES work at that point, but i have to boost the level way up to get any volume, gonna have to build a pre-amp for the audio i guess.

still got retrace lines, time to look at the blanking amp i guess, also, blue screel level is fluctuating slightly, bad cap or pot in screen grid circuit? R19 / C137 or something in B-Y amp affecting level?

CRT bias switch at lowest setting.

I think I see the problem with the retrace lines, the resistors on the blanking amp were never replaced, still all original. waveform on grid is perfect, @ 238v ptp, and at -82v R203 is old, measures 245k in circuit , plate is at 158v (too high should be 115v) suspect r204 bad measures too low in circuit, cathode voltage OK at 5.5v, should prob replace all (R203,204,205 206).

-EDIT, parts ordered, did not have any of the higher watt resisters on hand, will see if it works any better once they are replaced.

More luck, was able to track down a R-2AV2 (solid state) plug in replacement for the focus rectifier, in addition to SS HV rectifier coming today, so there will be even less stress on the flyback from heaters.

If I am seeing this right, once I get the resistors in the blanking amp replaced, & hopefully get the plate V to around 115v like it says in the SAMS, I should see an inverted wave of what is on the grid ( break out the 100x probe ) at C135 being fed to the cathodes of the G-Y / B-Y / R-Y amps if all is working as it should.