RCA CTC-36 Woes

[Kamakiri]

Originally Posted by andy

I have several CTC53s, and they all had a number of out of tolerance resistors on the horizontal and vertical osc board. Replacing them helped solve a lot of deflection/sync problems. I also found that several of the orange/brown/green drops were out of tolerance, or leaky.

That's no surprise. I kind of figure that if I want these two to be perfect, all new mylars would be the ticket, and resistor checks as well. At this point, though, it's an example of the law of diminishing returns.....the sets are both very watchable, and stable as they are. I've run each for several hours, and they're both now pretty solid performers, each having something slightly out of whack that doesn't really bother me.

I'll probably let these be for now and just run them (unless something fails), as I have a CTC-25A console that I absolutely LOVE that is going to need attention next. I have the sams for that one on the way now. I'm not looking forward to that one, as it's going to need cataract surgery as well. But I absolutely love the set, so it'll be worth it

There's only 4 sets in my humble collection that don't work at the moment. I'm starting to get scared that I'll be left with nothing to do pretty soon!

[Kamakiri]

[QUOTE=andy;3059484]

Originally Posted by dieseljeep

Those low focus voltage CRTs can really benefit from a very light rejuvenation, even if they test good. I've found the "cleaning" mode on my Beltron brings back razor sharp focus without being too harsh on the CRT.

I did exactly this yesterday, because the CRT seemed pretty dim. The CRT tested bad, bringing up the heater voltage to 8.8 and letting it cook for 10 minutes yielded a marginal improvement. Since it still has a watchable picture, though not really bright, I really hesitate to do a rejuvenate.....

[DavGoodlin]

Tim,
For the CTC36, look for the fold-out factory schematic in the RCA Color TV service manual you got from me. It is better than sams because the component numbers match the PW board labels.
The .01 cap you replaced may have been C608, which filters boost from rectifier CR606 by returning it to +280 volt via R618, a 1K resistor. This resistor also provides the screen voltage Check that 1K resisitor and try replacing CR606 - Im not sure you can really check the boost rectifiers but theyre all similar. See page 141 for text on the blanking circuit. As DaveWM said, the blanking diode CR605 needs checking. "Pops" tend to fry diodes.

The CTC53 IS a different animal alright, so a few items need checked to eliminate the easy stuff for the width issue.
The 31LZ6 Horiz output has a cathode protection via auxiliary thermal element in the set's circuit breaker, make sure the cathode voltage on this tube is less than 1 volt. Then check the 280v supply at pins 1 or 8 of the yoke plug.
next, see if the 130 volts at terminal T on PW400, where the tube is located, also check terminal BB (boosted boost) WTF that means, with a meter set on 1000 volt, you should see around 700 volts there. If this is OK, that clears your horizontal output stage. Last stop is the yoke...pull the plg and measure resisitance between pins 4+5, it measures the 4700 ohm 2 watt resistor in there.

I saw many of these as motel sets, no complaints since they kept us busy.

PS Nothing is better to do on bitter cold nights than this troubleshooting stuff...

[Kamakiri]

Amen to that!

I've put probably another 3 or 4 hours use on the set, and at the moment, it's about the same. Thing is, with the picture tube being pretty dim, and the possibility of finding one sort of remote, I'm wondering if trying to improve things as they are at the moment is worthwhile....especially since this works as is, and I have other sets to pay attention to .

This set is in my home office at the moment, where brightness isn't really needed. What do you think? If I'm going to risk other serious damage, then I might as well have at it.

Meanwhile, I have my 9T246 apart again, trying to bring it a few steps closer to perfection. After that, it's my '47 DeWald, then the RCA CTC-25 console.

[Kamakiri]

Thanks to bgadow, my CTC-36 has new life!

A friend of mine from MD brought up a bunch of TVs, including a pair of CTC-36 parts sets. Since one of the parts sets was totally rusted but had an excellent picture tube, I pulled the 19HNP22, and put it in my set.

Took me just under 3 hours, with coffee breaks and a lot of cleaning, about 45 minutes of alignment included in that figure. How the heck I ever did alignment without a cross hatch pattern I'll never know. Prolly why they never turned out that good

Anyway, here's a shot of the set with the new tube in, just before the cross hatch alignment. Thanks Bryan!!!!

[sampson159]

yes,bryan and kim are the salt of the earth!handier than a pocket on a shirt.set looks good!more screen shots,please

[Kamakiri]

Here's a couple more screen shots.....hard as hell to get a good screen shot with a camera, as we all know

Came out pretty good, I'd say. Still having the picture jitters until she warms up for about 15 minutes.....I just have to get in there and start checking some tubes.....

For some reason the convergence in these pics looks wayyyyy off. It's really not, it's darn close, except for a very little but of red shadow in the far upper right.

We'll blame the camera

[bgadow]

I was truly surprised when I tested that crt and saw how strong it was. I got that set working but with a real bad vert fold that I just couldn't get rid of. You saved me from having to chase it any more! Now I just need to find a home for those 3 CTC-53's out in the shed.

[Kamakiri]

The damper and horizontal output tubes in that set tested stone dead, but the 5GH8s were really good, so I transferred those over to the Mural set. I took the good caps out of the vertical section that you installed, and am saving those for another set. I'm saving as much of that set as humanly possible, but rust got to a lot of it. In fact, I had to hacksaw the clamp on the back of the picture tube to get it off.....which was kinda scary!

Funny, on the black case set, I saw that someone at some point replaced that same .047 ceramic cap on the bottom board that on mine, went off like a firecracker. Musta been a common thing

I ended up using the remains of the broken clamp from my CTC-36 to put back on the tube, but when I had the back off the Mural set, I saw that someone had used zip ties in its place. I thought, wow, why didn't I think of that! So, I'm gonna pop the back off the set again, test tubes, and get rid of that rusty broken clamp.

We had a temporary roommate for about 6 weeks that ended up using my CTC-53. Much to my shock, she ended up falling asleep to it every night, and it ran nearly every night all night for at least a month . But the thing never faltered.

[bgadow]

When I first started tinkering with old TV sets (c.1990) I found a CTC-53 at a junk store that worked but no color. I paid the local repair shop to fix it and the first night I fell asleep to David Letterman in color-and woke up to Today in black/white. Repair didn't hold. (I think all they did was change a 5GH8, but I wasn't that smart then) I paid another repair shop to do the repair and they fixed it right (changing the 5GH8 plus a resistor that had gone bad.)

[andy]

...

[Kamakiri]

Replaced some weak tubes in the CTC-36 today, and it seemed like the convergence drifted a bit when I decided to put up a crosshatch pattern.

Whoever at RCA that decided to put those convergence boards right underneath the top vents for the set should be shot dead, if he's still alive . Right where all the crap can fall right into it and screw up everything. BAH.

Half the controls do nothing, and I couldn't bring it back in to convergence perfectly. Vertical convergence is spot on, but horizontal, especially the right lower where you need to use those tuning slugs, is off. Incidentally, I discovered that the size for said slugs is a 2.5mm allen wrench, in case someone needs to know and decides to hit up Mother Google for the answer.

It's watchable, but dammit, I can almost never get proper convergence on an old color set....either the plastics holding something together crumble like an Egyptian scroll, or I can feel one of the control wipers skipping, or I turn it and it just does nothing

Can these pots be replaced with anything off the shelf? I have a spare convergence board that I'd give a shot at rebuilding, IF I could get new pots.

[Kamakiri]

Thought I'd share this....

I replaced tubes in the one CTC-36 parts set that I got from Bryan (bgadow), and managed to get a faint picture with bad foldover at the bottom, and no sound. Okay, well, let's try and save this set....

Figuring that I could start with a recap of the set to see how far that'd take me, I pulled the chassis last night. When you know how, it's child's play to do, just remove the yoke and convergence board first, then unbolt the tuner, and everything kinda slides right out

Underneath, this is what I saw. Ugh. Note the jumper wire unceremoniously tucked under the chassis on the right hand side bypassing the circuit breaker

I was surprised that the jumpered caps didn't short something out on the underside. There's quite a bit of rust on the chassis, but I still think I can save this thing.

[andy]

...

[Kamakiri]

I'm honestly wondering if this set is even worth rebuilding, given the condition....opinions?