Rca ctc-5

[DaveWM]

After talking it over, I think I will just check to make sure that all the existing values are correct and not try to up the HV more than the design calls for.

My concern is HV breaking down the insulation and arcing over in the HV tire.

I would rather have a dimmer CRT than no HV at all with a fly that is so hard to come by. I did try a new shunt, same HV 20kv. the old one was completely dark, which I presume is from Xray bombardment of the glass.

[miniman82]

Originally Posted by DaveWM

After talking it over, I think I will just check to make sure that all the existing values are correct and not try to up the HV more than the design calls for. My concern is HV breaking down the insulation and arcing over in the HV tire.

Won't happen, starting with the 5 there was a little bit of potting and a rubber insulator around the HV winding. Previous designs (CTC-4/21-CT-55) only had some wax dribbled around the bare windings, and they operated at higher voltage than the 5 does. CT-100 was different as well, it has some sort of plastic around the winding instead of wax.

It already makes 20kv, another 3-4 isn't going to hurt it. You don't have to drill a hole in the chassis either, you can use the pot temporarily to figure out what value you need. When you know, replace the pot with a fixed resistor and be done with it. The benefits are worth the potential risk, IMO. If I could get 23kv out of my set, I definitely would do it. Also, chassis for the 5 seem to be popping up lately. So if a flyback did blow, chances are you could find another one. It wouldn't be as hard as trying to locate one for a CTC-4, those are made of unobtanium.

[DaveWM]

while futzing with it I noticed the green was a bit weak, after screwing with drive controls, I finally decided to check tubes. Normally if they test a bit low on my mercury tube tester I don't sweat it, and one of them was a bit low. swapped in and color looks a lot better. per my tester SHB 3000, was about 1500, new tube was 2000 for what ever that is worth.

another odd thing was when I tried to use my vector scope the pattern was a mess on color bars. found out that if i disconnected the grid leads (so the vectorscope was not ready the chroma) the color bars on the screen look good, with in connected it was a disaster. I have never had a problem with the vector scope loading down the signal like that before.

oh the tubes where the 12BH7 difference amp tubes.