CTC5 Pickup!

[Yamamaya42]

however, do they really have to be mica?

81-RDE5C3A331J2M1H3A
75-561R10TCCQ82

my set has all ceramic capacitors.

Perhaps someone with a ctc-5 can give some insight,

[Davala]

Originally Posted by Yamamaya42

Yeah, it's those 1k mica caps that I'm a bit suspicious of, if one or both is leaky/ shorted, it may drive the heater/cathode v way to high, you might see this on resistance checks, not sure.

But new caps are not TOO much.
82 598-CDV19EF820JO3F
330 598-CDV16FF331JO3F

Mouser parts.

Ordered! Thanks!

[Davala]

Originally Posted by Yamamaya42

however, do they really have to be mica?

81-RDE5C3A331J2M1H3A
75-561R10TCCQ82

my set has all ceramic capacitors.

Perhaps someone with a ctc-5 can give some insight,

Looks like C115 is in a rectangular package, I assumed its mica VS round ceramic.

[Yamamaya42]

Originally Posted by Davala

Looks like C115 is in a rectangular package, I assumed its mica VS round ceramic.

that blue one is a modern Multilayer ceramic capacitor, like made for SMT, with leads on it for through hole.

[wkand]

Originally Posted by Davala

It's all been recapped... At least 45 capacitors. Wowiee. Maybe my Dumont ra-103 had more but I'm not sure!

There were some RCA black and white sets 20 inch and above, in the 1950s, that had over 50 wax caps. RCA loved them waxies. Part of that is the belief that tubular capacitors automatically have more consistent high frequency response. Admittedly it is much harder to properly select ceramics for high frequencies.

[Davala]

I should give an update! After completing my yearly recurrent training I was able to dedicate time to troubleshooting the horizontal section. Symptoms were horizontal off frequency, low HV.... and it caused TWO 6CG7's to short out internally.

I took three micamold style caps out of circuit and tested them. C115 was the culprit, leaking at only 50 volts. It's supposed to be a 1000-volt cap. I also replaced a couple out of tolerance resistors, nothing too crazy. Two 82K caps were both showing 91k.

I'm back to having a running CTC-5 although I'm dreading a full convergence alignment. The sides are really bad.

--
Matt Davala

[Penthode]

The convergence of my CTC5 wasn't bad once I read and followed the CTC5 service manual. The convergence process is somewhat different from later sets.

I have been able to achieve good overall convergence but it takes patience.

Also be aware of the general complaint of low high voltage. To get a bit higher voltage and improve regulation, I replaced the HV rectifier with a solid state 3A3.

[old_tv_nut]

I'd describe it as follows:

The CTC-5 does not have diodes to clamp the dynamic waveforms at the center like later sets, so in the CTC-5, points halfway between the center and edge stay motionless while the center moves the opposite of the edges. The trick is to rough in the DC in the center, then adjust the dynamics to get parallel R, G, and B lines, then fine tune the DC for best overall (and then maybe retweak the dynamic a tiny bit).

Hope your DC control pots are in good condition and not burned just at the proper setting point like mine were (both originals and replacements from a parts donor).

100 ohm carbon pot with tap at 25 ohms IIRC. Really pushing the limit on low total resistance for a carbon pot. I made up a substitution with 6 wirewound pots and three switches to pick a tap just above or just below or at the nominal tap point. If I was doing it again, I'd be tempted to try subbing a later cloverleaf with permanent magnet DC adjustments, but I don't know if the coils would be right for the dynamics.