AGC & NOISE GATE adjustments may be giving you trouble, to start with, be sure they are set at their center of adjustment.

For both of them, the more CW the pot is set, the more sensitive the tuning, the more CCW, the less it is.

Yes I had both already at mid point. That horizontal coil was so far one way the slug was out of the coil by an 1/8 but now it’s up inside close to half with good hv where I couldn’t get good hv unless the coil was out all this because the damper was bad so with an antenna maybe this will do it lol �� I’m almost burned out.

Ok I’m completely baffled plugged it in sound came right up all of a sudden I just about had a picture but was all distorted it come in and out I pulled the plug tried other tubes no different at all turned on again the sound was all but almost gone and the voltage started dropping again to the point of almost red plating the hot again. The sound sounded like something was interfering or shorting. There has to be a disc shorting to possibly ground to pull the voltage down like this as the picture flickered so did the sound.

Don't be focused on sound AND video at this point, that can come later, you have shown that things work OK from the detector forward with the video input yesterday.
For now, I suggest you remove V7, V8 ,V9 completely, and work on getting a clean input from the tuner to the screen.
Then once you have reached that point, put the sound tubes back in and then focus on getting sound.

Best approach it to get it up and stable section by section.

Ok voltage steady with those tubes out but the 6dt6 looks alittle white in side soi have another but still can’t get a pic it kind of flickers from almost a pic to snowy lines.

Well that was short lived tried some tubes and again voltage drop with audio tubes still out.

You should be able to cycle through all channels and see some sort of effect on the screen.
But, I do find that “sticky-gummy” condition of the tuner a little disturbing, if it IS old lube, (not sure) it may be interfering with contacts and hard to clean out unless something like deoxit is used since the RS stuff is hard to get, but It's a bit costly.
As far is I know, it should not be “sticky-gummy” in there, my Arvin TV tuner was like that, full of varnish, and it was hell cleaning it up.
I would still suggest a new set of IF/ tuner tubes however.

But the voltage pulled down again with audio tubes still out it has to be related and the contacts in the tuner very little dirt I did all the contacts no more sticky feeling wasn’t that bad at at.if a disc cap to ground is shorted is there any tell tale signs of maybe getting hot.

This then, is still likely a horizontal oscillation / sweep issue, as was pointed out way back, it is a giant feedback loop, if everything is not just right, the loop will collapse in on itself, oscillation stops, and the 6JM6s start to destroy themselves.

Where disc caps have been known to fail, it is very rare for them to do so, when they do short, they are hard to find, you often have to hunt for them by looking for a overloaded feeder resistor.

This is crazy I went over this chassis and found no bad resistors I am at a total stop the horizontal coil the oscillator tube and resistors around that area were good and the coil tests perfect ohms 85 another flyback numerous tubes I had changed the horizontal centering pot centering does work I also unplugged the horizontal from the yoke voltage still dropped 2 sets of power supply caps. What would cause an upset in the feed back loop.can a problem in the sound feedback to upset the video

This seems to be a very finicky set to get going, and it looks to be teetering right on the edge of working / non-working, could be any number of things, a cap or coil that is just not to it's liking, or when something gets warm/cold it starts/stops working, this seems to be one of the most dreaded of situations, an intermittent fault.

I would try to take a step back to where you had the most success, with tuner and sound tubes unplugged, see how long set can run with video input via test point B, 10min? 20? longer?
Does it mess up at all like that?

What happens is put on cold no problem with voltage warm up then turn off then back on that’s when the voltage problem starts after it’s warm.

There are only 3 tubes that seem to be connected direcly to power, audio output, sound det ( removed) and V6, SYNC SEP AGC/ NOISE CAN, if V6 is faulty, shorting when getting hot, this could be a problem and would not show in a tester, I have seen a AGC tube short before in a set and load power (it was a 6au6)

Well I have v6 coming it’s a 6hs8 in the mail and yes there is a lot of power arrows and that would mess up video and probably take down horizontal with all that power there. I have to wonder what killed the sound all the other times the voltage pulled down I still had sound.maybe for giggles I should put that tube on the tester to get hot and see if anything shows up maybe even put the heater up a notch. I tried it on the tester 7-8 v showing grid emission.

Well I have v6 coming it’s a 6hs8 in the mail and yes there is a lot of power arrows and that would mess up video and probably take down horizontal with all that power there. I have to wonder what killed the sound all the other times the voltage pulled down I still had sound.maybe for giggles I should put that tube on the tester to get hot and see if anything shows up maybe even put the heater up a notch. I tried it on the tester 7-8 v showing grid emission.

Won't be the same.

The TV has the cathode at 190v
https://frank.pocnet.net/sheets/049/6/6HS8.pdf
Max is 200v

the tester won't go that high for sure.

and you can be sure that in the set that it DOES go over 200v before everything heats up anyway.
so IF the tube is shorting, there is a good chance that it is mixing AC heater voltage with the 190v bias.
and IF it's failing then AGC is not working the way it should be, making the tuner deaf.

Sure sounds logical but would it knock out sound other then the voltage drop killing sound. Just curious if I should just wait for the tube or take a closer look at the audio.

Sure sounds logical but would it knock out sound other then the voltage drop killing sound. Just curious if I should just wait for the tube or take a closer look at the audio.

wait for the tube, right now this all is just best guesses bases on looking at the schematic.

this is the same type circuit in my arvin.
http://suzaku.live-evil.org/arvin111.jpg

it DID a hard short.
when you lose AGC, all sorts of strange tuning stuff can happen.

I’m already contemplating the next move if this tube don’t come out a winner. If this tube was shorting then it should have been extremely hot I would think but then again didn’t have it on long enough so the hot don’t burn up.

A tube with heater to cathode leakage/short wont get as hot as one that's overloading and running power to/from the plate, could even be colder if not conducting the way it should be, as no power is flowing from the plate as it should.

If the power is being pulled down by this tube I thought it would get hot resistance = heat.

It's a bit hard to explain, and remember, this is all founded on educated guess on what MAY be going on in the set.

In normal operation, there is a fair amount of power flowing between the plate and the cathode of a given tube, this causes the plate to heat up, and this heat is felt on the outside glass, if the tube has no power flowing but still has it's heater on, it would be much cooler.

And of course, if overloaded, MUCH hotter.
https://en.wikipedia.org/wiki/Glowing_plate

So, this could also mean that if there was a biasing problem like a H/K short or leak that would prevent the flow of power between the plate and the cathode, or any grid issue, it stands to reason it could be colder than normal. In the same way that a problem causing excessive flow makes it hot.

In other words, the radiated power from a H/K short has a much harder time making it to the outside of the tube than an overloaded plate.

So even though the tube is not getting super hot it could still pull the voltage down.I forgot to mention the 2nd chroma 6bL8 tube while I had the chassis on the bench and plugged in checking things I noticed this tube had what looked like a blue spot on the side of the tube but once in the cabinet I didn’t see it again.

For the case of V6 if it was having an intermittent H-K short (+190v to Y-HEATER/GND) the tube would not heat up very fast, your PWS might give up first, R215 before the tube got really hot, unlike when the audio tube or HOT was overloaded, and all the power was pushed to the plates, and the tubes heated very quickly.

What do you think of that 2nd chroma tube I mention in the last post.

a little blue glow is normal, it's just a spot of excitation from being hit from electrons.

I got a picture of a really weird one on a rebuilt CRT i got last year.

I thought any blue may have been gas in the tube.

Where did you get a blue mark on a crt

https://i.imgur.com/0ykFyqZ.jpg

Blue is not a problem.

pink , purple is.

https://tonetopics.com/tell-amps-tubes-gone-bad/

When I first started working on this set when I couldn’t get good hv I noticed the top of one 6jm6 was glowing blue I put another one in And that was what fixed the hv problem.

perhaps what you saw was a bad tube with a purple gassy glow, like seen here,

https://i.imgur.com/z7NnpHg.jpg

and not a normal healthy blue glow of a working tube?
:yes:

I just for giggles tested the audio output tube and it showed grid emission it’s a new tube and didn’t show this when I got it would this be caused from running hot because I’m still not sold on the fact that this tube is supposed to run hot. The volume control is 2 meg I tested it at 2.4 meg.

as mentioned. audio output tubes get HOT!

2 alike tubes.


https://frank.pocnet.net/sheets/049/6/6AQ5A.pdf 10w max gets up to 250c!
http://www.nj7p.org/Tubes/PDFs/Frank/127/6GK6.pdf 17w max no heat listed, but you can bet it also gets over 200c.

this is normal

Ok I’ll leave it alone just don’t get why it’s now showing grid emission

Ok I’ll leave it alone just don’t get why it’s now showing grid emission

As others have pointed out, don't take what any tube tester tells you as gospel, it's just a guide.

http://www.tungsol.com/html/faqs3.html

Lol got it.

When I got tubes for the set I had got 2 6eh7 tubes GE and I usually test them and in testing them they were completely dead no reading at all. Just never know what you might get. Someone should come up with solid state versions of tubes or if it can be done at all.

This is what I got and it would flicker to almost a picture but this is it.

This is all I get

since video input was OK, this may be a Tuner or IF problem. :(

This picture was taken just before shutting down and pulling the 6hs8 tube

unfortunately if this IS an IF failure, there is no way to track it down unless you know someone who has a piece of equipment like a Sencore VG 91 Universal Video Generator, and can trace which area has the fault.

It also takes exp to use.

If it is the tuner, yo can try to use a sub tuner like.

https://tinyurl.com/2fabnfdu

i have one of them and they DO work!

since you have no alt way to feed in a tuner source. a start would be a new set of tuner tubes, if this has not been done already.

esp the mixer/osc

Sams shows 2 diff tuners so you will have to look for what you have.

That pic you posted looks like a very weak input signal that the TV can't lock on.

as stated above, this can be because of Tuner and/or IF section.

While it does look like a weak signal but it will flicker and get really clear and a picture will almost appear I was able to see a person but then it went back to the snowy image.

Possible AGC problem?

Has the new V6 (6HS8) been put in?
This is the point one would use a scope to look for the 450v signal on pin 3 of V6, and the others.

Is the AGC line at tuner plug .4v? (pin3)
Bad M1/C8/C18/C14?

What is the video source? ( macrovision problem? )
have you tried changing the rf modulator input from CH 3 to 4, and see if 4 is any better?
Sometimes there is just too much rf interference on CH 3, and trying another may help.

I didn’t get the 6hs8 tube yet and the sound at one point seemed better on channel 4 and I use cable and the same line is good on all my other tvs.

I believe I changed those 3 caps already but m1 is a fuse wire if that’s bad then no power to the set.

I believe I changed those 3 caps already but m1 is a fuse wire if that’s bad then no power to the set.

that should have been K1, the couplet for AGC, I saw it wrong, the schematic is a bit fuzzy. :/

Where did you see k1 I can’t find it.

http://suzaku.live-evil.org/k1.jpg

it can be located via page 6 on the SAMs, left side 1/2 way down,

Ok that’s the network that has several legs on it I believe.

If that’s bad I Doubt I could locate that part it looks like it could be made up it’s all resistors.

If bad, it would have to be made up on a small pcb, It's been done before.
https://retrovoltage.com/2014/10/09/diy-replacements-for-vintage-couplets-and-printed-electric-circuits/

So this agc network would this be a cause for the voltage being pulled down via the 6hs8 tube ?

No, if not working the way it should, the AGC voltage/pulses would be all wrong, and tuning and IF would be all messed up and you would not be able to tune in anything.

Ok but when I get the tube I’ll try it but overall I still have the voltage dropping so if the tube don’t work out I’m still looking for a cause for the voltage dropping.

Timmy
Could you sum up what is wrong with the TV NOW without going
through the previous repairs.
In other words plug it in & see what happens like you never seen the set before.
I have lost track......

Prev screen shot looked good. But long distance troubleshooting is a challenge !
Many of us could take the TV like shown in the screen shot & vastly improve it
in seconds. That would maybe weed out problems.
Also remember NEVER trust a tube checker. The best checker is a known
good NOS brand name tube. We had an advantage here. I could turn
around & pull a tube from the shelf. It was abt 8' long & 5' high with sleeves of common tubes, more old numbers on shelves in the crapper.

73 Zeno:smoke:
LFOD !

Timmy
Could you sum up what is wrong with the TV NOW without going
through the previous repairs.
In other words plug it in & see what happens like you never seen the set before.
I have lost track......

Prev screen shot looked good. But long distance troubleshooting is a challenge !
Many of us could take the TV like shown in the screen shot & vastly improve it
in seconds. That would maybe weed out problems.
Also remember NEVER trust a tube checker. The best checker is a known
good NOS brand name tube. We had an advantage here. I could turn
around & pull a tube from the shelf. It was abt 8' long & 5' high with sleeves of common tubes, more old numbers on shelves in the crapper.

73 Zeno:smoke:
LFOD ! ok first the pic with the face was to rule out the video amp and output by injecting video. Turn it on b+ good few seconds later b+ drops and in doing so the horizontal oscillator won’t run because b+ is being pulled down to far so in using the sets IF cannot get an image weather or not the voltage being draw down has to do with that I don’t know maybe there is an IF problem as well. I have a tube coming maybe this is the problem I don’t know until I get it to try.

Got the 6hs8 no different but I did pull the 6cg7 AGC and vertical multi voltage stayed up I got a new 6cg7 made no difference so the one vertical half is working because I have a full screen so that may leave it to an AGC problem still bearly any sound scratchy static sound and with the 6cg7 in I can here a buzzing from somewhere. If k3 is bad or the cap inside is shorted I can make it up but it shows a line under the 94k resistor which is the .002 cap but it also shows a ground in the center of the line so where does the ground come from. I don’t remember seeing a cap with 3 legs. Does this mean 2 caps one on each side of the 94k resistor both to ground.

Does anyone know what this T line means 2 .002 caps one on each end of the 94k resistor

Does anyone know what this T line means 2 .002 caps one on each end of the 94k resistor

That is another couplet, like K1. K3 is a combo part, 2 resistors 1 cap in 1 package.

But the T does it represent 2 caps one on each side of the 94k

It intends to show .002 distributed across the resistor. When making a replacement put a .001 to ground on each end of the resistor so the total is .002

Is there another resistor that is covered by the black splotch?

remove V1,V2,V3 ,V7,V8.

feed video back to test point B like you did before and see how long it can run like that.

It intends to show .002 distributed across the resistor. When making a replacement put a .001 to ground on each end of the resistor so the total is .002

Is there another resistor that is covered by the black splotch?

No there is not only one for this area.

It intends to show .002 distributed across the resistor. When making a replacement put a .001 to ground on each end of the resistor so the total is .002

Is there another resistor that is covered by the black splotch?

A more common interpretation of the separate component intent of that figure
is two resistors of half the listed value in series with the listed cap value attached between their center to ground. That of course assumes that the big black dot is meaningless.

You really need to get or borrow a scope to sort out messy problems like these.

A more common interpretation of the separate component intent of that figure
is two resistors of half the listed value in series with the listed cap value attached between their center to ground. That of course assumes that the big black dot is meaningless.

You really need to get or borrow a scope to sort out messy problems like these.

and a better DVM. :yes:

Well I have more problems I plug it in to check video again and now I lost vertical deflection so this has to do with no video and recently sound was lost I originally pulled the 6cg7 and the voltage draw stopped pulling down so I put the tube back to check injecting video only to find vertical is gone and now the tube in and no voltage draw. So it’s like whatever was shorting now burned altogether and no more draw down. This set is really bizarre.

So now chassis has to come out and this time it’s not going back in until I find a problem or problems.

So I’ll cut the 2 couplets out and test them if bad then I make them.

remove V1,V2,V3 ,V7,V8.

feed video back to test point B like you did before and see how long it can run like that.

Well I never got the chance to pull those tubes , can’t run it with no vertical.

For something like losing vertical sweep, you will have to set the chassis up in the service position, if you have not done so already.

The makers of the set have anticipated the need for this, and normally left all wires long enough to prop the chassis up behind the set for easy access and still hook everything up, you just need to be sure the CRT is grounded.

Vertical deflection is dependent on 640v boost via 3 points, vertical height, vertical lin, and the output via C5, if this 640v boost has failed, or the parts it feeds have failed, vertical sweep will fail.
But to have boot voltage in the first place, horizontal sweep/ HV has to be working.

Yeah not sure how I’m going to do that being I don’t have the plug harnesses which would have been nice I’ll have to check into things first hopefully there’s something obvious. For no reason the vertical just dropped dead nothing I did except remove the 6cg7 tube for no more then 20 seconds. Well the wires may be long enough.

On k1 the schematic shows what looks like 24meg but on the schematic it looks like a dot next to the 24 so I checked early television museum schematic and it to looks like .24 meg is there a .24 meg resistor or is this a typo error.

On k1 the schematic shows what looks like 24meg but on the schematic it looks like a dot next to the 24 so I checked early television museum schematic and it to looks like .24 meg is there a .24 meg resistor or is this a typo error.

clearly 24meg 2w, hooked to 275v, going down to .4v it has to be.
not a typo, scan error.

No telling what could have happened, :(
Gonna have to re-check the whole circuit, including tubes, power resistors, potentiometers, caps, etc..
I see no real reason for vert to fail w/o V10 being in there, but on the other hand, if you hot plugged it in/out, that may be different, no telling. :/

Well this tv has tell tale signs of it having been in humidity and dampness so I think it may have been a momentary loss in one of the vertical pots as I turned the vertical linearity pot and was alittle stuck at first and I still have boost voltage and all the vertical pots check out fine and vary with turning them. That 24 meg measures 30.59meg slightly high.

Well this tv has tell tale signs of it having been in humidity and dampness so I think it may have been a momentary loss in one of the vertical pots as I turned the vertical linearity pot and was alittle stuck at first and I still have boost voltage and all the vertical pots check out fine and vary with turning them. That 24 meg measures 30.59meg slightly high.

at 20%, which is what it was most likely what it was made as, 28.8 would be the top, so 30.59meg is just a hair over, prob nothing to worry about.

The other resistors check good except for that 24 meg all I have is a 22 meg that measures 25meg so I may insert it in there with the one lead clipped. So I checked the other couplets and the both measure 115k while it should be up around 150k so I don’t know what’s with that.

The other resistors check good except for that 24 meg all I have is a 22 meg that measures 25meg so I may insert it in there with the one lead clipped. So I checked the other couplets and the both measure 115k while it should be up around 150k so I don’t know what’s with that.

or, you can hook this across pins 1-2

588-SM108031006FE Mouser part #

100 meg 2 w resistor.

the 2 in parallel = 23.424458228 meg.
or just leave it, it should be OK for a while. :yes:

While the other 2 couplets are measuring 115k don’t seem to low ? And that 4 volt source with no load should be higher then 4 volts.

While the other 2 couplets are measuring 115k don’t seem to low ? And that 4 volt source with no load should be higher then 4 volts.

again, it's very unlikely that the couplets are a source of trouble, they would have to be well out of 30% before you should even think to start to replace them.

now, they seem to be well on the edge of OK, and would be more of a pain to replace at the moment.

also, which 4 volt source do you mean?

The tuner pin 3

That shows .4 on my scanned copy, and by nature, AGC is going to change based on given input demand signal, so (if working) don't expect to see what it says there on the schematic, the AGC voltage should change reactivity to the strength of the rf coming into the tuner, adjusting it almost scan line by scan line,

You will note that AGC keying has a link to horizontal pulses via C59, & link to video via r58, this is how it monitors video level and times ACG control for the tuner & IF gain, with no video, it has no control reference.

http://www.earlytelevision.org/Deksnis/ctc2_keyed_agc_simplified.html

way more info on AGC :p

C59 is 470pf I measured 410pf does ceramic caps go down in value? As for the vertical it does have 640v boost.

C59 is 470pf I measured 410pf does ceramic caps go down in value? As for the vertical it does have 640v boost.

ceramic capacitors rarely ever go bad, and most in the set are 20% values unless otherwise listed, and it's very had to test in circuit unless you have a tester that was specifically made to test capacitors in circuit with leads that compensate, then a simple DVM will always give bad (deviated ) readings, especially with lower value capacitors because the length and position of the leads themselves used will skew the test results.

Notice the leads on this $1200 pro tester.
https://media.digikey.com/Photos/BK%20Precision%20Photos/LCR-600.JPG

And yes, and mentioned before the vertical uses the 640v boost in 3 areas.

Vertical Height pot R17, Vertical linearity pot R18 and it also goes to C5 to R109 / C3.

Any problem here, and you would most likely lose sweep.

If c59 was bad that would upset the video and possibly sound path.

The chances of being bad are very small, the way to be sure would be to use an oscilloscope on pin 3 of V6 to check for the 450v signal.

again I have never had to replace a Disc cap unless they were physically damaged, IE broken / burned, they pretty much never wear out in these sets..

I don’t know how the hv oscillator has anything to do with IF and sound again hv comes up no sound no pic pull the plug then back on and again one hot gets red about had enough. I could have 2 defective caps 0068 and 0039 for the oscillator so if it don’t start then the tube can get red plate. But the IF is definitely another on going problem.

The problem is multifaceted, look at the block diagram page 5, AGC uses pulses from horizontal output to control tuner gain, if horizontal oscillation is not running, or not correct, or AGC itself is not working, then tuner gain will be wrong and you won't be able to tune anything.
Sometimes, when AGC is not working for whatever reason, an external bias can be used ( battery or the like ) to force the tuner into the right range of gain for test purposes.

You don't know at this point if the horizontal oscillator is stable at the right frequency, or the right amplitude, or the right waveshape, all of this matters.

True I don’t know but I do know that recently I tuned the horizontal coil and was able to get a perfect stable -45 from pin 5 of the hot. Now it changed and cannot get it back to -45 so something is not right and maybe it’s defective caps because I found nothing in the circuit whatsoever that was wrong different tubes both oscillator and hot and still so all I have left is the caps in the oscillator circuit. So if it’s not a defective cap what else could this be it’s not a resistor I checked them several times and the horizontal coil 85 ohms.

Not having it in front of me, I really don't know what else to add, other than if the horizontal circuit keeps being unstable, go full shotgun, EVERY resistor, replace with new carbon film 2% 1w, there is 1/2w in there now, but the new type 1w carbon film are about the same size, and much more stable, it does not matter if the old ones stlll test ok, new ones will last another 50+ years, the same goes for the higher power ones, sizes have come down a lot, so if it has a 2w, put in a 3w , replace a 3w with a 4w and so on.

Replace all caps with higher tolerance and voltage ratings, except for ceramic discs, UNLESS they show physical signs of distress, disc caps almost never fail, as mentioned before, other types do, film types are less likely but the do sometimes.

Like resistors, film cap technology has much improved since the set was made, caps can be gotten with much better tolerance and voltage ratings at the same values now.

this all of course is just a suggestion ! :yes:

So the bottom line is if the horizontal oscillator is not right then the agc won’t be right and that can affect both sound and video even though in the beginning I did have sound but was alittle scratchy. All the film caps I put in are rated for 630 volts.

correct, horz is used as ref for AGC.


example

mouser part # for C83
667-ECQ-E6392JF
$0.69
5 %

So would using a 10% make that much difference in the oscillator circuit compared to a 5%.

So would using a 10% make that much difference in the oscillator circuit compared to a 5%.

The lower % part you can get, IE 5% 2% 1% and so on, the more stable it will be and less prone to drift with temperature change and age, and so on, you buy a 100 ohm resistor at 10% rating, expect it to BE within 10% of 100 ohms and stay there, 5% 2% 1% respectively.

when needed, I replace the carbon composite resistors with metal film 1% types.

The schematic shows only the .0039 400v but no % for that cap so how am I to know what was in there. The horizontal.

The schematic shows only the .0039 400v but no % for that cap so how am I to know what was in there. The horizontal.

It normally has it listed on the part, if it has no listing, a general rule of thumb is that it's a 20% part, unless otherwise indicated, and as always in these cases, it always helps stability to put in a higher tolerance part than you remove, because back when it was made it was a cost issue, putting in 10-5% or more parts was costly, but now, those parts are very cheap and effective.

Well now I look closer and the 2- 0068 and 1- 0039 are all 10% and that’s what I put in the print was small.

I read an article about AGC that the agc is for antenna connections but it’s somewhat not needed for a cable or any other video source so I don’t know if the agc is not working will it still knock out the video and sound from another source such as vcr cable line dvd.

I read an article about AGC that the agc is for antenna connections but it’s somewhat not needed for a cable or any other video source so I don’t know if the agc is not working will it still knock out the video and sound from another source such as vcr cable line dvd.

It absolutely will take out RF from a VCR or DVD player I've seen it happen on my own sets more than once.

The amp bias is controlled by the AGC circuit. If AGC is defective you can get absolutely no reception like the IF tubes are removed all the way to problems like signal overload and red plating IF tubes.

Ok I’m at it again the search continues for a cause for this horz oscillator agc problem I have yet to find anything obvious resistor or tube or anything else for that matter.

I don’t understand exactly if the 2 couplets or even one was bad if it would effect the horizontal drive because the 2 resistors within the couplet are 94k and 56k in series should be 150k it measures 114 and 115 k but the cap inside shows it should be .002 and my cap checker measures 3 times above the marked rating so I’m not sure at all if this would effect the horizontal drive along with the agc. Correction the 2 resistors do check ok at 165k and 170k so not so high on to the next.

One crazy thing after another this set is unreal it’s cursed. So now whatever was going on with horizontal oscillator it finally died and at the same time the 190 v source is dropping down to 38v and the 6hs8 is red plating. And yet again went over resistors and double checked the new caps I put in and nothing I can find. I hope the new flyback I put in is not defective.

Get an oscilloscope, already

Well, Good. A dead ocs. is better than one that only works partly. Ok, No Scope, Go find
an amplifier, make probes, couple the input of the amp through a cap. to protect it.
Horiz Osc. is 15khz, take your amp and put it on the Horiz Osc. of a tube tv that works, See
if it delivers sound, and does not kill the osc. Then you can see if your tv from hell has
any osc. action at all. You might have to use a coupling cap, and big resistor, 50K?
so as not to load the test circuit with the amp input. Be aware of that...

Also Remove the plate caps from the H. Output tubes and focus on fixing the osc. And
only focus on fixing the osc. Now that I think about it, you should forget about the tuner,
and other stuff, and focus on fixing the Osc. Use Voltage checks, on the Osc. tube & the
AFC. tube. Use the amp to see if you can hear the osc. Test the sound against another
tube tv, if it sounds faster, or slower, etc.

When the osc. is dead, what happens to the -45V on G1's of the H. Output tube?

Also with this tv working some time, and not others, working in the cabinet, and then not
have you thought there might be some intermittent bad connection? Have you tried
whapping the chassis really good a bunch while it's on to see if symptoms change??

I mean whapping it like Onslow from Keeping Up Appearances......
Anything less is not considered a whap.....


.

A scope would help but it will tell you a tube is bad or resistor or flyback or capacitor or horizontal coil all of which i ruled out except the new flyback I put in. The ohms on the original flyback is different then the new one I won’t say drastic but different.

Notice pin 8 of V6 on the 6HS8, it gets power from 640v boost via R92, if the horizontal oscillator is NOT working, then this voltage is obviously not there for the plate to use, making the tube NOT happy, it will try to get power from someplace else, like the grids, this can overload and damage the tube.

From what I understand, V6 is not needed in the set for horizontal oscillation to take place, can be removed while you debug the horizontal oscillator circuit, it IS needed to sync it to incoming video however.

And as been stated many times by many here, an oscilloscope, even a crappy $35 one, would be a great aid to you at this point.

What if the ohms on the flyback were out to a degree would this prevent the oscillator from running. With the 6hs8 out the 190 rail is dropping bad down to 35 v. I think it’s obvious that whatever the problem was has now disabled the oscillator for good which is a good thing maybe now I can somehow track it down so now it’s a dead short probably between a resistor otherwise it would burn the fuse wire.

Possible short/ bad part, there are 8 connections to the 190v line, all must be checked, starting with both sides of R215, if 275V is OK, then R215 is suspect, or C2c, or anything that connects to 190v.

But, that is the reason for loss of horizontal oscillator, it needs 190v to work, find why you lost 190v, and it should work again.

Most likely suspects are, soldering errors, opens or shorts.
or
C61 , R215 ,C2 section c

All other links to that line are via 2k or higher resistors, and would be getting quite hot if shorted.

I had subbed another cap c2 c and the 15k resistor checks 18k so on to the next.

18k is just on the outside edge of tolerance (20%) and very out of 10%.

You may wanna change it with a new 1w 15k one.

Cap cap c2 c subbed with 10uf 350v?

Any chance that the 190 and 145 volt supplies are swapped on the schematic? The 15k resistor appears to be too high a value for the current that it must supply. The 190 supply as shown appears to be very weak!

:scratch2: jr

The 190v I never had a problem with that rail until now and the 15k resistor is getting warm like there is a draw and I pulled half the tubes and the cap I subbed was not 350 10 it was bigger voltage and uf

Any chance that the 190 and 145 volt supplies are swapped on the schematic? The 15k resistor appears to be too high a value for the current that it must supply. The 190 supply as shown appears to be very weak!

:scratch2: jr

And yes that would have made more sense for it to be the other way around since there is only 2 connections and 190 having 8.

You will have to track down what the draw is, I would still suggest replacing that 15k with a new 1w one, then follow the 190v line to every place it goes, it has to be something, if it's feeding a resistor that's shorted on the other end, then that will be getting warm. As mentioned, 18k is a tad bit high, you have nothing to lose by replacing it with a same value 15k 1w resistor, it will just be more durable.

I have a 15k 1 watt wire wound I could put in but I know that won’t fix it I will have to trace down all 8 locations that feed 190v.

Chances are the problematic end also has a resistor on it's side and is getting warm as well, an IR camera would be handy for this such thing.

For a number of years as a teenager, I worked on TVs without an oscilloscope. When I finally got one, I couldn't imagine working on TVs without one. Even a cheap one with low bandwidth would make it a lot easier for you to troubleshoot this set. An oscilloscope will tell you whether an oscillator is running and if the waveform is correct. You just can't do that with a DVM. You should be able to find something on eBay. I got my last one from eBay and it was a high end Tektronix for a very good price.

If my house were to catch fire, the Tektronix oscilloscope is the first piece of gear I would remove. 'Nuff said.

Well there are several 2 and 3 watt resistors that normally get hot and up until now I had all tubes out and still a draw and the 275v is around 250v so if one goes down all are going to be low as well. So at this point I’m still thinking it may be a ceramic cap that may have been a problem and now is possibly shorted. How to find I don’t know it means turning this chassis into spaghetti with all clipping and checking and resoldering. Omg what a headache.

Running raw w/o tubes is not recommended, UNLESS you limit input voltage with a variac.

Reason is, the power supply is non regulated, and dependent on load, the tubes in the set ARE that load, w/o the tubes in the set, the voltage generated can exceed the ratings of the filter electrolytic capacitors and damage them (internal shorts), when you run w/o tubes one must be very careful not to let the bias voltage spike above the rate the capacitors can tolerate, or it can be really bad.

I only tried it for a moment and was watching voltage either way it’s still a disaster.I don’t want it to run to long and stress the fuse wire and or the power transformer or anything else for that matter.just prior to the voltage drop off I think the flyback was buzzing I know they don’t do that but the buzz was from the flyback area.

Here is how I see this set working ( my take on it ), you have the thermistor R211, cold at 26.5 ohms, as it heats up. It gets lower, they put this in as a protect timer to keep the bias low as the tubes warmed up as not to shock the caps with overvoltage until the heaters were warm enough to load the circuit down enough.
Without tubes in the set, this feature is defeated, and the bias out of X2 at C1 can easily reach over 400v or more and may have damaged the new electrolytic capacitors you have put on there, of course there is no way to know for sure if this is what has happened, but it is possible.

I have been thinking the same thing about the caps not being able to handle ripple. But without the tubes I only did it for around 10 seconds and I did watch the voltage.

As for the caps if one it shorting then it could effect the b+ network since they all go to ground except for one section but I’ll be checking them.

Changed the caps still 190v pulling down I didn’t change the 2 250 160 uf being the initial voltage is little over 400v but slowly drops because of the 190v dropping. Still the dark.

Put in the 1w wire wound 15k resistor you have for R215, then check on the other end for warm resistors that they are giving power to.

And, if you have not done so at this point, replace disc capacitor C61, that is the only one that is NOT going through a resistor on the farther side of the 190v line, all others have current limiter/ voltage drop resistors that should be warming up with power pushed through them.

This again can be related to V6 cathode or even the socket, as it is the only tube that has a direct connection to 190v w/o going through resistors.

The whole point of putting in the new larger watt R215, is so it will heat up less, and hopefully make the problematic heat more and easier to find, it's bad anyway at 18k.

Yes I already changed the 15k and it to gets warm and c61 I took one leg off and tried it still pulling down and the cap tests good unless the problem is somewhere else and it’s affecting v6 red plating. V6 out still have the draw down.

More then likely this is the whole problem this set has with the oscillator and video and sound it seems maybe the problem started out small and finally shorted out to whatever or wherever it is I can’t check resistors anymore because they are all good so it don’t leave much else but possibly a disc cap.

You still have no HV, and therefore no boost, so it's a bit odd for it to be red-plating, as there should be no bias on pin 8.

Try voltage check on each pin of V6, with tube in and out, monitoring voltage as the set is turned on.

Ok there was a resistor pin 7 of 6cg7 to pin 1 of v6 which is the 190v source the resistor is a 560k it checked.800k so I changed it and I felt it and was warm so I disconnected one leg and the hv came back and it’s stable at -45 so if I put the resistor back the voltage pulls down so there maybe a problem at v10.I’m thinking the 56pf cap may be shorted since it’s tied directly to ground and the 56k resistor is 61k.

R93? OK , getting someplace, power has to be going somewhere, leaking out C66 or C65 , or even R94? C66 prob.

if bad, it must be replaced with another N750 class or better type.
https://www.tedss.com/LearnMore/Ceramic-Disc-Capacitors

or else it wont be stable.

R93 is the 560k after I changed r94 is a 56k it measures 61k so what’s left but the 56pf cap. .022 is new I double checked that one.

R93 is the 560k after I changed r94 is a 56k it measures 61k so what’s left but the 56pf cap. .022 is new I double checked that one.

Well if you have a NPO one, that would be even better then N750 class.

More trouble I clipped one end of the 56pf and pulled one side of the .022 still shorts with the resistor connected but good with it off. This is nuts I thought the cap was it.

there is only 2 places for the power to be going then, R94 (internally bad ) or V10 has a short grid to cathode. this will be evident by the wrong voltage on pin 7.

Ok I’ll look into that r94 that’s a 56k that measured 61k v10 I tried a new one befor ever removing that resistor and it made no difference. Would the vertical hold pot being disconnected have any impact on this.

So actually the 190 is feeding the 560k resistor to v10 where it’s being pulled from that point when it’s attached to v10.

So actually the 190 is feeding the 560k resistor to v10 where it’s being pulled from that point when it’s attached to v10.

yes, R93 R94 is supply power to the grid of V10 A pin 7

So actually the 190 is feeding the 560k resistor to v10 where it’s being pulled from that point when it’s attached to v10.

How far is the voltage dropping?

jr

How far is the voltage dropping?

jr
From 190v to 40v

From 190v to 40v

Since it is unlikely that the small current through the 560k resistor, even if it was shorted to ground (only 0.34 ma for 190 volts), would load down the 190 volt supply, the real load appears to be that V10 gets turned on hard when the 560k resistor is connected, and it’s increased plate current is loading down the weak 190 volt supply. :scratch2:

jr

there is only 2 places for the power to be going then, R94 (internally bad ) or V10 has a short grid to cathode. this will be evident by the wrong voltage on pin 7.
I’ll clip that resistor and check it again but it can’t be a short grid to cathode since the short is still there with the tube out.

Since it is unlikely that the small current through the 560k resistor, even if it was shorted to ground (only 0.34 ma for 190 volts), would load down the 190 volt supply, the real load appears to be that V10 gets turned on hard when the 560k resistor is connected, and it’s increased plate current is loading down the weak 190 volt supply. :scratch2:

jr
When v10 is out short still there.

None of this makes any sense here, given on the info provided.

You are saying this.
If R93 is disconnected, 190v is no longer loaded, and you get HV, but it's not C66 or V10 cause you tried it w/o them in the line.

Odd.

Things to try.
Disconnect R93 from the 190v line and hook a 620k 1w resistor from the 190v line to gnd ( aprox R93 +R94).
If it's able to keep 190v up and get hv, then the resistors in the set may be bad, even if the meter says good.

Or C65 is leaking, the 190v line does not have the power for the plate on pin 8 of the 6hs8 if C65 is leaking and trying to power it.

Also this could be a combo of things.
What is the voltage in/out and across R215.


Here are all points 190v feeds.

1- V6 cathode p1 C61
2- V6 g3 p9 R90,R89
3- V10 g1 p7 R93,R94
4- V12 g2 p3 R124
5- V21 plate p1 / cathode p7 R168
6- pullup R160
7- V21 g1 p2 r169 r170
8- pullup r149

Ok here is an admission I hate to say but in looking for a problem with the horizontal oscillator I came across the 560k and I went and used a 560k wire wound 3 watt temporarily not knowing this won’t work then temporarily I put together 2 resistors to make up 560k well this obviously didn’t work so I did find the right resistor and no more short got hv but could this resistor having been at .800 k have caused the horizontal oscillator to quit. I hope this resistor restores the IF and sound I don’t know if this resistor is critical in if it drifts up some it will affect the IF and oscillator.

Ok here is an admission I hate to say but in looking for a problem with the horizontal oscillator I came across the 560k and I went and used a 560k wire wound 3 watt temporarily not knowing this won’t work then temporarily I put together 2 resistors to make up 560k well this obviously didn’t work so I did find the right resistor and no more short got hv but could this resistor having been at .800 k have caused the horizontal oscillator to quit. I hope this resistor restores the IF and sound I don’t know if this resistor is critical in if it drifts up some it will affect the IF and oscillator.

This is getting very confusing...
you are talking about R93? “.800 k” is 800ohms, way wrong for the part.
What is marked on the part exactly?

R93 560k when I first checked it was.800k.

which should have been marked green blue yellow silver (20%) gold for 10%

but...
.800k = 800 ohms.

does it still test like that out of the circuit ?

Well your right I screwed up again 560k green blue yellow but I just realized that the 560 I have here is green blue brown but it tests 560k some meters once over 500 it will show k or meg so now I have find one that shows k ohms without the decimal befor the 500. Omg this set is making me nuts the old 560k I took out measured .800k

Ok what I’m going to try is a 470k and a 100k together in series and I checked is .560meg that’s better if it works then I’ll go on to check voltages on v6 and v10.

That's why it is always important to look at the part under test, and not rely on the SAMs alone, cause it can be wrong, or not have updated part info, if the color code on the resistor says 560k and it tests as 800ohms, it clearly bad, but if they stuck an 800 in there for some reason, or a 3.3k like is shown in the (3300) option on the sams, it all depends on what is really in there, but most likely, it really WAS a 560k to start with (green blue yellow silver ) in there, and it drastically went down in value.

Oh I never rely on sams there’s always been mistakes so I do look at what’s in the chassis as I already found that there are parts not listed in the sams and yes I did look at the resistor and I knew it was 560k

Back to the same thing before sound is scratchy distorted and the -45 is jumping all over -39 -41 -30 and so on I can help but think maybe this new flyback is bad oh and no video.

So, you are saying you have gotten HV back and have a raster again and now back to the point of not able to tune in video?


So it's suggested again that you try a longevity run with video input at test point B, like you had it hooked up there before, ( removing 3rd IF V3), and work on sound and tuning after.

And as it says on the schematic, all voltages and waves are taken with test pattern input, w/o such input, it's understandable that voltages and waveforms will fluctuate as there is nothing to lock them into “normal” ranges.

So the -45v can fluctuate without anything to lock on to so is the horizontal oscillator and agc used with video input at test point b and the IF tubes out ?

So the -45v can fluctuate without anything to lock on to so is the horizontal oscillator and agc used with video input at test point b and the IF tubes out ?

you can leave the other IF tubes in, and remove the 3rd, as it could interfere with the input.

As for AGC, the set has a combo tube, AGC SYNC SEP, , the latter being needed for video lock.

so all that's needed to be pulled is V3, the rest can stay, they will just have nothing to do with no input if they are in the RF/IF stages.

Ok here’s what it looks like and the -45 came back.

Unfortunately, tuning/IF problems are some of the hardest ones to debug, even with something like a B&K 1077b television analyst or the like, no easy task at all.

You might want to start with a voltage check at the tuner plug, working back through the IF stages 1-2-3. looking at grid, plate & cathode voltages, that may tell you something.

But if tuning / IF is out of alignment, there is little to do other then hope to find someone with a sweep marker generator setup, and who knows how to use it.

What gets me is at the beginning I had clear sound and it slowly went to static distorted sound.

It could also be the tuner it looks like at one time the cover was removed and maybe putting it back maybe cut a wire inside. But still I had sound and if I had sound that would usually mean the tuner is good so if the IF is out I should still have sound.

sounds almost like an AGC/noise gate issue, advancing those controls CW has no effect?

Neither one makes a difference at all and I thought it was odd that if I touch the antenna to the uhf terminals I get the same thing as if it were on the vhf terminal. I even tried the old tuner tubes. Well the tuner is not immune from drifting resistor’s.

If the tuner is out, there is very little, if anything that can be done about it, cause there is nobody around who works on them anymore. :sigh:

They are very hard to work on as you end up doing more harm than good unless you really know what you are doing.

And as stated before, they have these to find out if it really IS the tuner that is faulty.
https://www.ebay.com/itm/165634220782?hash=item269091a2ee:g:UoUAAOSwYCJi~vD w&amdata=enc%3AAQAHAAAA4EIdY%2F05A3Dq1r2MCxczZ%2FCRW jeM9pFSWUAK5EwUPinOzTroD4mu6JFGKl1mIDTlK65QIN3Q4b6 CbyVfmYKbZAFvQ9NvZhySyYUEIlaZNqQdMK2ShZn7Q6LuDC5si xGj1Nbz6%2BWRcUa30M19CeAJkPKzaGN2ynX4XxYbH%2BAeOI6 JPh7KXJpkNs1GNV0SdTjtLl4Pz3tFFfdrK9jyG6A3VpdISR91b rBU9yyW%2BympbRnaJNh%2FXUwog20AAk4nPDsyok6v9RRvRAh klEulKiipDr4kdynbFFIMSV4Gn35y8%2FPt%7Ctkp%3ABk9SR_ DcmuTsYA

Well I have worked on watches very tedious work so if I have to I would attempt it and the unit on eBay how is that hooked up.

Well I have worked on watches very tedious work so if I have to I would attempt it and the unit on eBay how is that hooked up.

I have one just like it, except mine has the AC option, that is battery only, (2 9-volts ), it simply acts as a substitute for the tuner you are testing, you unplug the RCA type cable from the tuner in the TV and plug it into the sub tuner, then feed the RF into it, set to whatever channel, adjust tuning and gain, see what happens, it's easy to use.

Yes I seen it I’ll get it and this chassis has an rca type plug from the tuner that plugs directly into the chassis right at the first IF and that subber looks like it has rca on the back.

Yes I seen it I’ll get it and this chassis has an rca type plug from the tuner that plugs directly into the chassis right at the first IF and that subber looks like it has rca on the back.

Yes, that type of “RCA” IF connection is universal on most sets of the era, not sure when it became a standard.

Ok I had enough of this set I bought that subber hope it works so I’ll know if the tuner is bad or the IF is bad.

Yes, that type of “RCA” IF connection is universal on most sets of the era, not sure when it became a standard.

On TV IFs I think it started to become common in the mid-late 50s. It never was standard on TV tuners. Many brands simply had a couple of solder stakes to solder the coax to the tuner and that was a common cost saving measure up until the combined tuner/IF systems of the solid state era.

The RCA jack as a standard connector for consumer coax applications (primarily audio) dates back to pre-WWII IIRC.

And if it turns out that your IF section is hopelessly borked / misaligned, you always have the option of bypassing it all and going direct A/V input, this of course would require making a small 2 transistor simple video amp to boost the standard 1v video level to the 5v that this TV expects at the 1st video amp tube grid, otherwise things will look washed out, and sound can be easily added in on the volume control plug.

That tuner subber don’t have a fine tune is it crystal controlled so that channel 3 is 3 aside from having the gain control. Or I could have a power supply to power the subber and leave that in circuit but I would rather keep it original if I can.

Back to the same thing before sound is scratchy distorted and the -45 is jumping all over -39 -41 -30 and so on I can help but think maybe this new flyback is bad oh and no video.

What does the 190 volt supply measure when the set is “working” ? Is it still somewhat low?

jr

The 190v problem is solved had a bad resistor

The 190v problem is solved had a bad resistor

So it is now putting out 190 volts?
Which resistor was bad? :scratch2:

jr

So it is now putting out 190 volts?
Which resistor was bad? :scratch2:

jr

R93 had changed value to 800 ohms, from 560k, believe it or not :scratch2:

There seems to be a lot of believe it or nots with this set.

It’s almost as if the 6hq5 rf amp tube in the tuner is bad or extremely weak I have a sub I’m Going to try.

That tuner subber don’t have a fine tune is it crystal controlled so that channel 3 is 3 aside from having the gain control. Or I could have a power supply to power the subber and leave that in circuit but I would rather keep it original if I can.

I have the 4-c version.

http://suzaku.live-evil.org/0922222215.jpg

that other one prob DOES have fine tuning, note the difference in the tuning nob, the wider control behind the one you got may be fine tuning.

Well I hope it works after all it’s from around 1974 I don’t want to have to fix it to get it to work lol.

So if the tuner subber works and I get video and sound then it is the tuner so I checked that it has 130v and 145v and that’s good There is a 4700 ohm resistor after the 130v and 1200 ohm after the 145v so if I have to get into the tuner those 2 resistors are what I’m going for first.

R93 had changed value to 800 ohms, from 560k, believe it or not :scratch2:

Two other common examples of resistors going down. All IIRC numbers.
GE 18" S-1 compactron POS sets had an 8.2K 2W that went way down.

Sylvania 19" hybrids two 56K 2W that went between the high B+ & the
24 V for the color ckts. They went down & smoked lots of stuff in
the color.
Other than those I cant remember any other fails with ohms going DOWN.
On Motos I do remember big brown resistors in the demod opening
& giving missing colors.

73 Zeno:smoke:
LFOD !

Two other common examples of resistors going down. All IIRC numbers.
GE 18" S-1 compactron POS sets had an 8.2K 2W that went way down.

Sylvania 19" hybrids two 56K 2W that went between the high B+ & the
24 V for the color ckts. They went down & smoked lots of stuff in
the color.
Other than those I cant remember any other fails with ohms going DOWN.
On Motos I do remember big brown resistors in the demod opening
& giving missing colors.

73 Zeno:smoke:
LFOD !
Soinds like the D-12 Sylvania chassis they put that chassis in consoles too.

Got the tuner subber works good but it looks like the problem is in the IF strip having the subber in and increasing the gain I can see an image but all distorted along with sound so now back to the drawing board focusing on the strip.what causes a ceramic cap to be shiny and greasey looking while there are several other disc caps next to the one that’s shiny yet only that one and not the others next to it.

Got the tuner subber works good but it looks like the problem is in the IF strip having the subber in and increasing the gain I can see an image but all distorted along with sound so now back to the drawing board focusing on the strip.what causes a ceramic cap to be shiny and greasey looking while there are several other disc caps next to the one that’s shiny yet only that one and not the others next to it.

plz post pic of the screen image.

Same as the other image I posted only alittle more detail with the gain all the way up and I already pulled the chassis

Same as the " Godzilla " one last week? :O

This one but the gain up on the subber things are more able to make out

I know without a scope to get past each IF tube to rule out is going to be a tough nut to crack. I originally had sound but the one day it just fizzled out if the volume is up I still have sound but scratchy static so since the sound is off the 3rd IF it can still be anywhere from 1-3 IF tubes.

Unfortunately, this means that the IF is most likely badly out of alignment, most likely been tweaked.
Where as something like this MIGHT be caused by a bad component, if it was, it would more often than not be a faulty resistor than a bad capacitor, or even less likely a coil, cause as stated before, disc capacitors seldom ever go bad unless subjected to physical or electrical extremes, and since you have gone through and tested the resistors already, options are limited.

You may try to check all voltages on the pins of the IF tubes to see if they match what is listed in the schematic and hope to find something drastically wrong, but failing that there is not much else to do, other than hope to find someone with an alignment test setup, to debug/align the faulty stages, or bypass the RF/IF stage completely and go direct A/V input.

I don’t think it was tweaked because I had good sound and now it’s all static but can here the sound it self and I had a picture flickering in and out with the subber gain at max so I’ll have to go over resistors again and clip if I have to.

Is it possible that there is a problem in the sound detector v7 being the sound is off v3 3rd IF if there is a problem in the detector would it affect both sound and video seeing as both sound and video comes off the 3rd IF. Just a shot in the dark.

they use Intercarrier for sound, it's folded into the video.
C43 is the bypass cap for the sound det, sort of works like an FM radio, what is most likely going on is that by the time it gets from the tuner to the 3rd IF, the signal is so distorted, there is nothing for the sound det to work with.

The loss of sound has got to be why I can’t get video because I had sound initially it’s got to be the same problem unless it’s a really hard coincidence

What about the 1n60 if that is leaking I know it would take out the video but would it affect sound

The loss of sound has got to be why I can’t get video because I had sound initially it’s got to be the same problem unless it’s a really hard coincidence

it's the other way around, until you have clean video IF pathway, sound can't work, since sound is riding on top of it.
In some cases, (bw sets ) they take sound off after the video det diode.

Well maybe I should change every disc cap along the 3 IF tubes because there are no bad resistors that I found I tried different tubes there’s nothing left but these discs.

Before going that far, on the 3 tubes, taking voltage checks of pins pin 7,8,2,3 should tell you something.

voltage listings are on the SAMs.

Before going that far, on the 3 tubes, taking voltage checks of pins pin 7,8,2,3 should tell you something.

voltage listings are on the SAMs.

Is that with an antenna on

Is that with an antenna on

should not matter, but give it a signal, to keep it happy as it says, " taken with signal input".

Now this is interesting first tube 7- 191v 8 - 67v 3 - 15v 2- 8v Second tube 7-195v 8-59v 2-13v 3-13v Third tube 7-212v 8-214v 2-0v 3-2.6v

Stage 3 seems OK, but WTF, with 1 & 2, may be a hand in hand problem with AGC control V6 via K1, as stage 3 does not seem to be linked as 1-2 are.

K1 I checked the resistors in that and were good and that crazy resistor network thing there maybe one of those big 3 watt resistors are bad but I think they are wire wound

If c15 and or c19 were shorted would this cause the voltage loss on those 2 tubes

Since it's most likely the first 2 stages acting up, what I would do in most cases, is resistors first, caps second, even if the DVM says they are OK, don't trust it in this case.

Replace R38,R39,R40,R41,R42,R43,R44,R45,R46,R47,R48,R49, R50 with metal film types of high quality 5% or better 2%-1%, and then, if no change is seen, then look at the caps.

What caps are you referring to and how is this pulling the voltage down on those 2 tubes

What caps are you referring to and how is this pulling the voltage down on those 2 tubes

these resistors set the bias for those tubes, and if they are just not right, things may go out of wack, even though they may test OK, under load they still may be suspect, so replacing the ones mentioned may help.

So are you referring to the ceramic caps because that’s the only caps at these tubes. What could possibly cause this with only the first 2 tubes and not the 3rd if there’s something on let’s say the first then the second should show good but what is in common with the both it don’t seem to make sense that resistors on only the 2 are bad and not the 3rd.

R45 on the schematic shows it’s a 560 ohm but when I measure it it gives me .551k but I know sometimes any resistor that is over 500 ohms it shows me it in k ohms same thing with the other 560 resistor. This one is green blue brown.

So are you referring to the ceramic caps because that’s the only caps at these tubes. What could possibly cause this with only the first 2 tubes and not the 3rd if there’s something on let’s say the first then the second should show good but what is in common with the both it don’t seem to make sense that resistors on only the 2 are bad and not the 3rd.

This is based my own experience, and what others have told me about IF problems, added with the fact that ceramic caps are much less likely to fail than the older carbon composite resistors, this coupled with the indications of the incorrect voltage readings you gave pointing to problems with the first and second stages, meaning that is where the problem is MOST likely to be, I'm suggesting that you take the older carbon composite resistors in the first 2 sections out of the equation, even if they test OK with your DVM, who knows how they may act under full power and load, the end result, you will have better more stable and longer lasting resistors in there when you are done.

And then after that is done, then look for any possible shorted disc caps if it is still not working, but keep in mind it still may be an alignment issue.

R45 on the schematic shows it’s a 560 ohm but when I measure it it gives me .551k but I know sometimes any resistor that is over 500 ohms it shows me it in k ohms same thing with the other 560 resistor. This one is green blue brown.

good site for this is..
https://www.allaboutcircuits.com/tools/resistor-color-code-calculator/

but it does not give down to 20% :( you have to work that out for yourself

An alignment issue can keep the first 2 tubes from conducting the proper way or can they conduct and show correct voltages when an alignment is needed.

So I am going to pull the first tube and check the voltages on the second and if the voltages are good on the second then that narrows down to the first tube having a problem if not then first one back and I pull the second and check voltages again hopefully I can get it down to one tube I can’t believe that both tubes developed a problem at the same time.

An alignment issue can keep the first 2 tubes from conducting the proper way or can they conduct and show correct voltages when an alignment is needed.

It does make some sense that if the alignment was off, that the tube dynamics would be upset to some degree, but how much, who can say.

First tube pulled 7- 252 8- 136 3-5 2-4
Second pulled with first put back in 7-242 8-130 3-7 2-15v

It's almost as if the alignment is WAY off, and AGC is trying to compensate for it by messing with the gain of stages 1-2.

the numbers gave today are relatively normal, compared to the ones yesterday, namely voltage on pin 8, (130ish ) where it was 60v ish last time you tested.

This is probably being caused by.
AGC changing gain of these tubes.
Changes in voltage on the 275v line.
Changes in value of the 3w/2w power resistors on pin 8 as they heat up.
This added with the fact that the alignment is most likely off to start with.

Don’t voltages normally go up when a tube is pulled? And I checked voltages also with no antenna and no change.

Don’t voltages normally go up when a tube is pulled? And I checked voltages also with no antenna and no change.

the draw of an IF tube is so small, it won't matter that much, in or out.

Well I don’t understand how a 100v drops to 60v that’s not so small of a draw I would think

Due to the action of the AGC, the 1st and 2nd IF is in constant flux, using horizontal pulses and video as reference points, even with garbage video, AGC will try to gain on those tubes via cathode and grid 1, this of course will have an effect on the other tube elements when this takes place.

Where it's hard to be sure why that 100v on pin 8 dropped liked that, it's unlikely that it was because that 275v was low, so it's prob tube biasing and / or related to the age of the resistors in the area coupled with the fact that alignment may be off.

Alignment is all but impossible to correct given the current situation, but upgrading to better resistors is a pain, but rather cheap.

I can’t help but go back to having sound stronger on channel 4 then 3 but the one day I had the set on and the sound just faded into distortion and static but can still make out voices and that’s how it still is so if alignment was the cause sound would not have been good in the beginning so I still believe the loss of sound has got to be the reason for bad voltages and no video.

So if you think the agc is trying to clean up a bad signal then what if I pull the 6hs8 agc tube then see if voltages get better on the first and second IF tubes.

Well pulled the agc tube didn’t make a difference.

Read page 8 of the sams, where is says “alignment instructions” , the better choice is to do as it says, connect a variable voltage to point A, and adjust to what ever needed, 3v 4v 2v, this overrides the AGC control, for alignment, this can sometimes be done for testing.

I think I’m going to try and get the 12 caps across the IF strip and change them. there are some that are shiny almost to say they got hot or whatever the reason is they get the oil or wet look. Something took out the sound that I had. maybe I’ll get lucky and find one that is leaking or partially shorted. I checked voltages this time with no antenna and pin 8 on both tubes still low.

It's not uncommon if a set was in a living room close to a kitchen or if there is a coil or transformer containing wax close to a part for it to get an oily or waxy look. One check you could make if you don't have a leakage tester is to put a cap of over 10X the value in series with the low voltage end of the ceramic caps ( a .1uF will work for anything smaller than a .01uF) then measure the DC voltage of the point between the two caps. The voltage may initially float up but it should 0 out within around 10 seconds of connecting the DMM...If DC voltage doesn't 0 out within a reasonable amount of time you have leakage.

Putting a large test capacitance in series with a small test capacitance will yield an effective series capacitance close to that of the smaller capacitance, and the greater the difference between the two the closer the effective value comes to being unchanged from the existing small value.

AGC does need manual bias voltage injection if the automatic part is disabled....Heck if the automatic part is not disabled, but isn't working right using a manual bias supply to force it to the value it needs to be can be used as a troubleshooting procedure...The exact voltage it needs to work may be different than the one listed in the alignment procedure as the signal level may be different and the alignment procedure may desire adjusting amps at min or max AGC gain for linearity reasons.

I would strongly advise against changing capacitors unless you can prove failure. Changing caps WILL make alignment needed if they were not defective before replacement.
Changing resistors to 5% or better modern replacements typically fixes alignment issues if the original was bad, or barely changes anything if the original was good (provided lead dress is carefully kept the same).
I have on 2 CTC-2 and 2 CTC-4 sets fixed egregious alignment issues by replacing all resistors that were off tolerance or at the edge of tolerance with modern tighter tolerance parts....On the CTC-4s the sound, luminance and chroma were all so far apart from each other on the fine tuning that you could only get 1.5 out of 3 in good at once (you could get any 1 of the 3 in alone good at a different fine tuning spot) before resistor changes, and normal fine tuning and operation after resistor changes.

I would strongly advise against changing capacitors unless you can prove failure. Changing caps WILL make alignment needed if they were not defective before replacement.
Changing resistors to 5% or better modern replacements typically fixes alignment issues if the original was bad, or barely changes anything if the original was good (provided lead dress is carefully kept the same).
I have on 2 CTC-2 and 2 CTC-4 sets fixed egregious alignment issues by replacing all resistors that were off tolerance or at the edge of tolerance with modern tighter tolerance parts....On the CTC-4s the sound, luminance and chroma were all so far apart from each other on the fine tuning that you could only get 1.5 out of 3 in good at once (you could get any 1 of the 3 in alone good at a different fine tuning spot) before resistor changes, and normal fine tuning and operation after resistor changes.
That’s the kicker here I haven’t found any bad resistors anywhere I had sound but it fizzled out to static and distortion can here voices but it was there almost to say a resistor went really high but found nothing that’s why I’m now looking at caps leaking or shorted.

That’s the kicker here I haven’t found any bad resistors anywhere I had sound but it fizzled out to static and distortion can here voices but it was there almost to say a resistor went really high but found nothing that’s why I’m now looking at caps leaking or shorted.

But, as mentioned before, that is only what your meter is telling you with the set not in operation, things MAY change when power is on with the older carbon ones.

By carefully replacing them with 2% film types, you take that out of the equation, many have said before, disc caps are the most reliable types of caps used, and pretty much never fail unless physically damaged, and as EM stated, replacing them in this situation raises the chances of needing a full alignment to 100%

Trying something different on the bench got speaker hooked up and while I monitor the voltage on pin 8 of the first IF and at the same time using the subber when I probe at the 8.2pf no change in voltage but when I go ahead of that cap and the coils that the antenna goes threw I probe pin 2 of the same tube and the voltage goes from 64 to 70v for all I know maybe lightening hit this set and maybe damaged the coil or the 8.2 pf cap.

AGC will react to any kind of input to the grid of the 1st IF amp, be it a clean RF source, or noisy garbage and alter tube bias on pin 8, you so much at get a finger near C10 , let alone touch the leads, on the input side, ACG will change the bias of the tube.

Ok the 680k in k1 I subbed and the voltages went up from the 60s to 90 on first and 85 on second so you did say k1 were in common with the first 2 IF tubes. The 680k measured 744k not so high but this may be critical.

I also got the sound back nice and clear I will never take for granted that a tube is good because the tester says so it was the detector tube tests great but was no good and the voltages are 90 85 195 and I figure the voltages should come up alittle more once it’s back in and the tuner is plugged in. I hope this time I have video.

I’m going to make a new couplet k1 and being it has to do with the IF is it essential to pot it in some sort of epoxy or just on a small board.

Now I’m showing excessive currant on the -45v side of the hot. I think this flyback is crap got a dim screen.

Now I’m showing excessive currant on the -45v side of the hot. I think this flyback is crap got a dim screen.

this makes no sense... is was OK before, your last post stated " make a new couplet k1" was that done?

if so, it clearly upset something, try putting it back the way it was before.

this makes no sense... is was OK before, your last post stated " make a new couplet k1" was that done?

if so, it clearly upset something, try putting it back the way it was before.

No I didn’t make the couplet until I get resistors I only had the 680k the others are so so but in trying to set the -45 I noticed I can’t get it to -45 and the screen is dim at 22kv and with the meter on number 5 of the hot my meter is showing 1.3 amps on the ac scale but I had it set to dc but I know this meter if there is excess current it shows on the top scale and you are right none of this makes sense but I will tell you that I had to adjust the horizontal coil to get the oscillator going initially after getting a better signal to the IF but I took to look and the hot both turned red so I don’t know if I damaged the flyback because of that I don’t know and I’m preparing put the original flyback back in because I don’t trust the new one this maybe affecting the agc and the IF.

this makes no sense... is was OK before, your last post stated " make a new couplet k1" was that done?

if so, it clearly upset something, try putting it back the way it was before.

Or was the degradation of performance due to putting the chassis back in the cabinet/reconnecting everything? :scratch2:

jr

I really don't understand what you are trying to say, there is no “setting” of the -45v on the grid of the HOT, and that is not an absolute value by any means, it is a general voltage in DC, that means the horizontal oscillator is running.

There is no current measurement there.
DC voltage only.

The ONLY current measurement is cathode current, and this is done through a coupling cap AND a current meter for both tubes independently, but only when the set is up and stable.

The meter you have does NOT have the range to do the cathode current test, so don't try.
I'm not sure what you were attempting, but nothing but dc voltage measurements should be done on the grid of the HOT.

This tv is a huge cluster fxxk I tried 2 new hot no different and I tried a new 3at2 no different oh and now the 3 b+ voltages are low 275 is down 15 v 190 down to 185 and the 145 down to 138v this is nuts all I did was the 680k and that’s it.

I don’t know at this point if the hot both get red for to long if it would damage anything other then the 2 hot

No I didn’t make the couplet until I get resistors I only had the 680k the others are so so but in trying to set the -45 I noticed I can’t get it to -45 and the screen is dim at 22kv and with the meter on number 5 of the hot my meter is showing 1.3 amps on the ac scale but I had it set to dc but I know this meter if there is excess current it shows on the top scale and you are right none of this makes sense but I will tell you that I had to adjust the horizontal coil to get the oscillator going initially after getting a better signal to the IF but I took to look and the hot both turned red so I don’t know if I damaged the flyback because of that I don’t know and I’m preparing put the original flyback back in because I don’t trust the new one this maybe affecting the agc and the IF.

I'm still quite confused by what you were doing here.
"trying to set the -45 I noticed I can’t get it to -45 "
what were you doing here?

what steps taken, what was adjusted , if anything?

the screen is dim at 22kv and with the meter on number 5 of the hot my meter is showing 1.3 amps on the ac scale but I had it set to dc but I know this meter if there is excess current it shows on the top scale

How exactly is the meter connected to pin 5? Are you perhaps trying to use the AC-only clamp on jaws to measure DC?

jr

I'm still quite confused by what you were doing here.
"trying to set the -45 I noticed I can’t get it to -45 "
what were you doing here?

what steps taken, what was adjusted , if anything?

The horizontal oscillator/ hold coil I was able to adjust it to -45 with no problem because I found when it’s adjusted it’s one less thing I need to do but I know now that if the agc is trying to do what it does well then I waisted my time but now I’m stuck with a dim screen. And when it’s set to -45 the hv adjusts easily but now the hv won’t go over 22kv.

How exactly is the meter connected to pin 5? Are you perhaps trying to use the AC-only clamp on jaws to measure DC?

jr

Ground and positive on pin 5 no clamp I think my meter was sensing ac from somewhere.