Ctc-7aa

[IsthmusTV]

Hi Guys,

Yes, I think I'll just change the fuse holder to a more standard type instead of continuing to use the oddball ones (and certainly not the "no-blo" fuse it came with, LOL)!

I'll be careful when cleaning. Fortunately, this one doesn't have greasy kitchen grime or nicotine deposits.

In addition to the boxed tubes, it came with an original RCA service manual that is correct for the chassis complete with a fold out schematic. It's a little beat up, but usable. It contains notes from a TV repair shop with a previous owner's name dated 2002. So someone has been poking around in this thing fairly recently.

-Clark

[kvflyer]

BTW, I apologize for not congratulating you on finding and saving this piece of history. Glad that you have it in your hands. It is much cleaner than the CTC-9 that I have as mentioned above. Mine came with a booster on the picture tube. All three guns registered zero emission even when the filaments were cooked on 8 volts for about 30 minutes. Luckily I had a used CRT for it that was very good. I gutted the three electrolytic capacitors and stuffed them, brought it up on a variac with a Kill-A-Watt in series with it and got a raster. So, I know all of the major components are good. Please keep us posted...

[IsthmusTV]

Thanks, kvflyer. The is the one and only color roundie that I've been able to locate around here after months of looking. I'm going to take my time and try to do things right. I just placed a cap order with Mouser so that I'll have what I need to re-stuff the power supply electrolytics. I'm keeping my fingers crossed about the power transformer. I hope to have some time to work on this over the holidays.

Merry Christmas and Happy Hanukkah

-Clark

[47'Plymouth]

Congrats Isthmus!
I'm redoing a 7AH console with remote control,..mine had a BAD power tranny from a lighting strike from many years from the 1st owner leaving it plugged in during
a Thunderclap..got mine for $20 bucks 2 years ago at a estate sale locally nobody wanted it...its in great shape also all over except..having a blown tranny
got a new one from Moyers..last one they had on the self...found the thermo-switch is bad also..wonder how you would replace that?

[IsthmusTV]

I did find some time this week to work on the chassis. It had been sitting on my workbench in a horizontal position for four or five days undisturbed. When I lifted the chassis, I discovered that a big blob of transformer goo had collected:



Apparently, being horizontal got it flowing in new directions. Keep in mind, that I still haven't applied power and that the temperature in my workshop is about 60 degrees. This is a pretty large quantity of stuff. Is it possible that some sort of internal seal broke allowing this stuff to flow? Here's a shot after I scraped it off the carpet square with a penny for size reference:


On other fronts, I replaced the kluge repair with a proper resistor. I also found a charred 5600 Ohm resistor feeding the plate of the 12AZ7 color demodulator. It measured 144 Ohms! I wanted to find what had caused this overload. The 12AZ7 measured a bad HK short. In addition to the tube and resistors, I replaced a couple suspect caps in the vicinity:


I did use Phil's approach to the PS electrolytics. It all went pretty smoothly:


I also added a standard fuse holder, leaving the old one on place:


Two of the cans were definitely toast! I didn't even need heat to pull out the innards:


I ran out of time for now. I'll finished the third cap this weekend and attempt a first power up. BTW, all the windings on the power transformer look OK with an Ohm meter so I'm still reasonably optimistic that it will be OK.

-Clark

[IsthmusTV]

It's alive! I finished changing the PS electrolytics and did a first power up. At about 85 Volts, I heard the thermal relay close and the HV spooling up and saw the first raster


I added a signal source and got this at about 100 Volts. The audio was excellent:


At 117 Volts, it was drawing 2.25 Amps with no sparks, smoke or bad noises. The horizontal was close but wouldn't lock:


The picture was nice and bright with good focus. I'm very relieved that the oozing power transformer is OK! It didn't get even warm to the touch after about 20 minutes. It even looked like the color locked for a while.

So a lot seems to be working well with this set. I'm going to recap the horizontal and vertical boards first and go from there. When I pulled the chassis, there were no signs of overheating anywhere, including where I replaced those resistors and caps. A nice start to the new year!

Happy New Year to all.

-Clark

[miniman82]

Since you recapped it the horizontal frequency is probably off, tweak the slug on the board to get it back and you should have a watchable picture!

[IsthmusTV]

What I wrote wasn't very clear. At this point I've only recapped the electrolytic cans in the power supply. I'm preparing to recap the horizontal board now. I tried adjusting the frequency throughout its range and it won't lock. This is exactly what Phil Nelson experienced with his CTC-7. The horizontal wouldn't lock until he got rid of the maroon drops on the horizontal board.

I hope to have a watchable picture by tomorrow!

[kvflyer]

Originally Posted by IsthmusTV

What I wrote wasn't very clear. At this point I've only recapped the electrolytic cans in the power supply. I'm preparing to recap the horizontal board now. I tried adjusting the frequency throughout its range and it won't lock. This is exactly what Phil Nelson experienced with his CTC-7. The horizontal wouldn't lock until he got rid of the maroon drops on the horizontal board.

I hope to have a watchable picture by tomorrow!

That absolutely makes sense. Unfortunately, it seems that almost every vintage capacitor is now leaky. And since the Horizontal will not lock, there must be a capacitor issue in the horiz section. Looking forward to the picture of the locked image on the CRT.

[DaveWM]

can you flop the horz lines? or will it just go one way like its out of range of adj?

[miniman82]

Originally Posted by IsthmusTV

What I wrote wasn't very clear. At this point I've only recapped the electrolytic cans in the power supply.

Oh. Well in that case, I'm surprised it works at all!

You'll surely have a very nice picture on it when you go through the paper caps in the rest of the chassis, don't be afraid to pull the metal cover off the color section underneath and have some fun there as well. There's at least 10 more hiding under that hood. Don't come hollerin' though when you wind up needing a matrix alignment, mine was so far out of whack from previous repairs gone wrong, it took me 2 weeks to figure out what the manual was asking me to do. After I figured it out though, it was a snap and now the set has a nice picture indeed.

[Electronic M]

Congrats!

Now you know that the unobtainium is all good.

[kvflyer]

Originally Posted by Electronic M

Congrats!

Now you know that the unobtainium is all good.

Isn't that the truth! Congratulations! Glad to see it.

When I stuffed the filters of my CTC-9, replaced the CRT and got a raster, I was happy. But it will have to take its place in the queue!

[IsthmusTV]

I finished recapping the horizontal and vertical boards. I didn't have a .001 @ 2KV for the vertical board, so I left that one for now:



When I fired it up this time, I was able to get the horizontal and vertical to lock easily, and a pleasant surprise-- color lock!






Not bad considering all the maroon drops that remain. On this chassis, there is no metal cover over the color section and everything seems pretty accessible.

To me it looks like the CRT is badly in need of degaussing (or is it purity)? And of course, I got rid of my degaussing coil years ago. Is there any kluge that I could improvise to degauss the CRT? I think I have a small tape head demagnetizer

I'm very pleased at how this is going so far!

-Clark

[stromberg6]

WOW!