Ctc-7aa

[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