RCA 21" triage CTC20 CTC16x CTC12

[Yamamaya42]

You have me curious enough to see what that wave looks likes on my GE CTC-15 & ½ , not enough to pull apart my 16 and look, but I wanna see what that wave looks like.

Also. This may be a dumb question, but you have replaced X9 in that 16xl , cause I know the damn things have the stupid Selenium phase detectors, and when they work, they work, but when they mess up, it's pure HELL!

The GE has silicone.

[DavGoodlin]

Originally Posted by Yamamaya42

You have me curious enough to see what that wave looks likes on my GE CTC-15 & ½ , not enough to pull apart my 16 and look, but I wanna see what that wave looks like.

Also. This may be a dumb question, but you have replaced X9 in that 16xl , cause I know the damn things have the stupid Selenium phase detectors, and when they work, they work, but when they mess up, it's pure HELL!

The GE has silicone.

I have replaced the horz AFC diodes, both video and sound detectors tested OK on my fluke. I wasn't looking on the convergence board for a problem yet, but some issue is lurking there like that Zenith I worked on.

The GE CA chassis has a similar video circuit to the '15, usually trouble-free.

[Yamamaya42]

Originally Posted by DavGoodlin

I have replaced the horz AFC diodes, both video and sound detectors tested OK on my fluke. I wasn't looking on the convergence board for a problem yet, but some issue is lurking there like that Zenith I worked on.

The GE CA chassis has a similar video circuit to the '15, usually trouble-free.

the difference in the CTC 15/16/XL in that part of the circuit is almost non existent all use 6ka6 and almost the same circuits for generating sync.

and my GE is a hodge podge of the 15and 16/XL

what mine looked like
https://i.imgur.com/w05ehHg.jpg
and it was like that all the way to the AFC input I did think your flat tops looked odd, I would think, that if you found what was causing that, would fix most of the problems IMOH.

[Yamamaya42]

I think I'm starting to understand a bit more about what GE did with this thing and why RCA has a Shark Fin wave and GE has more of a sinewave in the horz AFC , RCA has the lower diode of the phase detector grounded, and GE added filtering, WHY GE chose to change RCA's design, who knows but that is neither here nor there when it comes to the problem with your set,
having never had too look that deeply into that part of my 16, i never really got that into it.

[DavGoodlin]

A double post

[DavGoodlin]

As to your Horz AFC diodes, I wonder if RCA's patents would be infringed, yet the GE is mainly an RCA clone. The 6BH11 and another few tubes were GE's finishing touch. The only CA I saw was in HS, where we had one with a dead red gun so nobody wanted it, as we thought a bad CRT meant death to any TV 40 years ago. Who knew they were so interchangeable and you would still find good CRT's in otherwise abandoned TVs.

The sync is indeed messy on this 16x and that garbage riding signal can be traced all the way back to 1st video stage. I am spending too much time going in circles, literally circling back to the same places to find where the phantom junk originates.

When I get back on the 16x, electrolytic caps will all be replaced, like SOP on any vintage set. But Im not sure that is the cause because bridging all the PS caps with an 80 uf / 450 v did not produce any improvement. Then again, this still could be THE whole problem.

[JohnCT]

Originally Posted by DavGoodlin

The sync is indeed messy on this 16x and that garbage riding signal can be traced all the way back to 1st video stage. I am spending too much time going in circles, literally circling back to the same places to find where the phantom junk originates.

It's been 40 years since I've seen a 16 much less worked on one, but one of the things we used to do with an issue like yours is to disable the sweep and see if the noise went away. The nice thing about a power transformer TV like the 16 is that it gives you the opportunity to remove any tube not associated with the circuit that seems to be suffering from spurious noise.

John

EDIT: LOL, I actually *remember* the last CTC16 I ever handled! It was somewhere about 1977 or so and I swapped it (with a new picture tube) for some minor body work on my 1973 Gran Torino. Johnny's Auto Body on West Main St. in Waterbury CT!!

.

[Yamamaya42]

As you may recall, it took me months to get mine working, mostly trying to get color working, and sorting out the mess that the person/persons who worked on it before I got it.
Almost EVERY resistor on the color/video pcb had been replaced with carbon film, almost all being correct values, I think that only 3-4 were wrong, 10% of the caps were replaced, color takeoff coil and bandpass also replaced before I got it, and the most disturbing sign was that the cover for the IF section was gone.
For almost ½ year, nothing I could do could get color via the tuner, but I got barberpoleing if video was fed into 1st amp, but no color lock, this was found to be because of a partially open color osc coil, fixed and BOOM color, took a while to sort that out, but still no color from tuner.
Then had the idea to go back 1 stage, unhook the video detector diode and feed video in there, NO COLOR, ding! The 4.5mhz trap was way of, some putz had tweaked it, I adjusted it while feeding in video at that point, and was able to get color via the tuner after that.

My set works pretty well now, but there are a few minor stuff.
It's obvious the IF has been messed with and can use alignment, which I don't have the setup to do, it works but not as good as it should, so I have direct input option.

Vertical blanking does not work well as it should, retrace is seen sometimes, most likely related to C31, still original part.

Shadowing in relation to light and dark objects on screen, IE, bright stationary credits on darker background, symptom seen often in these sets, also most likely due to old caps in video output.

As I deem these minor, and can do nothing about the IF, I leave it as is.

But like someone alluded to, restoring a vintage color set is like fighting a trench war with one arm and leg tied behind your back.

Slow , steady , methodical!
As suggested above, disable what is not needed and see what happens.

[DavGoodlin]

Originally Posted by JohnCT

It's been 40 years since I've seen a 16 much less worked on one, but one of the things we used to do with an issue like yours is to disable the sweep and see if the noise went away. The nice thing about a power transformer TV like the 16 is that it gives you the opportunity to remove any tube not associated with the circuit that seems to be suffering from spurious noise.

John

EDIT: LOL, I actually *remember* the last CTC16 I ever handled! It was somewhere about 1977 or so and I swapped it (with a new picture tube) for some minor body work on my 1973 Gran Torino. Johnny's Auto Body on West Main St. in Waterbury CT!!

.

Thanks! If I still have AC getting in where it should not even after doing 100% of electrolytic caps, there are tubes I can pull like the damper, HOT and osc, HV regulator even.

[DavGoodlin]

Originally Posted by Yamamaya42

............
But like someone alluded to, restoring a vintage color set is like fighting a trench war with one arm and leg tied behind your back.

Slow , steady , methodical!
As suggested above, disable what is not needed and see what happens.

After reading the VA-48 manual, its a better way to check alignment than doing the factory thing: marker and sweep gen with need for clamping AGC, etc.

You will probably tinker some more with that set over time, it looks like you have great equipment, that did not exist in the 60s.

For about 7 years now and thanks to the internet leading me to awesome folks like this forum has, I have tripled my number of projects and just now I start to recall the persistence needed. I feel fortunate to be the first one in other than tube-swappers, to see these sets as they came from the factory. To be sure, I have been able to repair super-dogs that showed evidence of long bench hours..

Each time I populate these with tubes and fire them up, my intent is to reassemble the TV again and if not 100% ready for home or sale (?), trade it to another collector. That's what we do to keep each other sharp

Out to the barn I walked, thru 8 inches of snow this morning to get some tubes from about 6 caddies, and sorted vegetable flats. Caddies are all full of boxed tubes but often used/tested are found in boxes. But I did get a new 6EA8 for the tuner, several 6BK4s. I try to pick RCA tubes if possible with dates close to 62-35, date chassis is stamped.

I just fired up my CTC12 starting at 70 then up to 95 volts AC, got some RF on the 6DQ5 cap evidenced buy my neon stick, no hot stuff or smoke and good sound. pics up soon

[Yamamaya42]

And now for something completely different.

looking up your scope i find...

https://www.youtube.com/watch?v=aMli33ornEU
Weird!

[old_coot88]

I usta do this on the shop scope to impress the Boss (no audio of course). Used the Z input on the back of the scope for luma.

https://www.youtube.com/watch?v=hqKssQYLWaA

[DavGoodlin]

Originally Posted by old_coot88

I usta do this on the shop scope to impress the Boss (no audio of course). Used the Z input on the back of the scope for luma.

https://www.youtube.com/watch?v=hqKssQYLWaA

Very cool thanks for posting this. I worked at two companies in the 80s that were Defense Contractors and they had a zero-tolerance for any outside radios, players, walkman, etc. I had an uber-expensive HP spectrum analyzer and the receivers we made used headphones, that is all you needed plus an antenna to get FM. Several of us were able to listen to the Iran-Contra hearings on WAMU from DC, then we talked about it in the lunch room. The DCAS guys were the G-men who came in to audit procedures, etc. These guys were in to audit while I was listening to WWDC-101.1 and pretending to work on a receiver, still could not help but laugh up my sleeve at the whole affair, my headphones were plugged into the spectrum analyzer the whole time.

My Tek-516 is huge and the RCA WO-91 is just a bit tricky to measure voltage, but the Hitachi scope is fast and portable. Is this what you do at work if "TV sets" are not permitted?
I bought it from the son of a repairman from RI. He lives above my storage garage and one day showed all this stuff of his Dad's he was trying to sell on Ebay. I made a fair offer and got the scope, a Lafayette signal generator and some RC sub boxes.

[Yamamaya42]

O_o

Stop making me feel like such like one of the “Young Ones” here, in the 80s, I was still in the middle of my school years, watching as much MTV as I could on a 19 inch BW tube set that I got someplace, recording rock and all sorts of stuff on my voice of music 722 reel to reel deck, including The doctor demento show, annoying my parents by blasting the home with sound from my Sansui 1000 which was more powerful than anything they had at the time!

[DavGoodlin]

The generation 20 years later has easily picked up what we sometimes learned ONLY the hard way by having to make a living fixing other peoples TVs. Watching some of DRH4683's videos on U-toob I cant believe he's 20 years younger. I was positive this would fade by the late 80s and what I see on this forum, ARF and FB give eternal optimism.

Being fortunate to grow up with a tank-like Motorola BW ('63 like my avatar), a '46 Philco transitone AM in bakelite (my Dad's at age 12) then a 71 Zenith color TV at age 8, the smell of hot dust on tubes was irresistible. For the next 5 years, I had real modest stuff in my room and was not allowed a TV until age 13 when the old Motorola BW came back dead (just the line thermistor) from its travels. I also got a working '63 Zenith BW (16K20?) that my uncle left on their porch for summer ballgames.

I toasted my Fisher 610 receiver chassis' iron over the summer leaving it on overnight listening to any myriad of stations that thing pulled in with ease. I saved $27 from painting jobs and bought a GE C-4315 AM-FM clock radio just in time for 8th grade. The FM reception was poor, so I opened it up and ran an external antenna out and added external speakers. I later got the guts of a Motorola Stereophonic with 4x6BQ5 outputs and the rest is HiFi history.

MTV went on cable the same year I graduated HS and left for the big city of Allentown, moved into an apartment complex which was in a terrestrial dead-zone, cut off from the PHL and NYC, TV and FM. We had a series of Zenith, RCA, Magnavox and Admiral sets there hooked to cable with FM simulcast of MTV, HBO and some others. The Dynaco amp and speakers became our very own "pro-feel" system at least power and sound quality rivaled a new Sony then.