CTC5 Pickup!

[Electronic M]

The CTC-5 has all the yoke plugs at the back of the chassis so if you can find sturdy box or cooler approximately the height of the rear chassis shelf you can test the chassis outside the cabinet by setting it on a box behind the cabinet with the back of the chassis facing the cabinet.... You'll also want a clip lead between the metal parts on the CRT and the chassis....with sufficient cunning you may be able to set the chassis on its side and have access to everything while its connected and running.

[old_tv_nut]

[Davala]

The CTC-5 made it through the Hobbit DVD reliably. I wasn't sure how my bandpass transformer fix was going to hold up. Its so nice to have color and it looks so good on the 21AXP22A

The sound out of these speakers is amazing!

I'll try and not play it too much at one time to avoid stressing the flyback. Our B/W set we had in the living room would run 10 hours some days straight. I'll not be doing that with the CTC-5.

--
Matt Davala

[Davala]

Not so fast....Watching the set last night I would loose horizontal lock and was having to tweak the horizontal pretty far to get lock, nearly full clockwise. Then it would pop out of sync and I'd have to go to where it was originally set. I did this at least 4 times. Then after 4 hours I couldn't the horizontal to lock at all and the width shrunk too.

I tested the 6cg7 tube and found it had a short and wouldn't test on either section. I popped a brand new one in there that tested great. Same issue, no lock and poor width, assuming low high voltage. I pulled that 6CG7 out and it showed a short now! Thats not a cheap tube to be wasting away troubleshooting. So now I'm out of 6CG7's until my ebay order of 4 of them ships monday.

I'll do some testing in that section, there really isn't too much going on in that board. Any ideas on what would cause the tube to short out internally?

I thought this set was ready for the living room! I should have done the burn in testing in the garage.

--
Matt Davala

[Yamamaya42]

Even though the SAMS shows no cross for the RCA 102259 x-fomer, one may have been made after it was printed, and COULD be listed in a later Stancor or Merit,Triad,Thordarson, cross reference manual.

I'm sure someone out there has them and can see if any type of sub exists!

[Yamamaya42]

As for the horizontal issues, if you have not already done so, make sure there are no out of tolerance resistors in the circuit, having no VDRs in this set in the sweep area makes it prone to out of tol parts and aging more than the later sets.

Also, since parts were replaced, it's critical to go through the steps shown in the SAMS under Horizontal Sweep Circuit adjustments, this will get things most stable and lower the risk of frying the flyback.

[Yamamaya42]

OK, something is not making sense here, you put in a NOS 6CG7 and it blew right away?
You say it shorted? How, H-K?
If this is indeed the case, then you have had something critical fail in the area to cause it to push the tube way beyond it's max ratings if it shorted that fast, like an open resistor or shorted capacitor.
You should be extra vigilant in looking at every related part and finding the cause before destroying another way WAY overpriced tube, thank you audiophiles very much!

[Davala]

Originally Posted by Yamamaya42

OK, something is not making sense here, you put in a NOS 6CG7 and it blew right away?
You say it shorted? How, H-K?
If this is indeed the case, then you have had something critical fail in the area to cause it to push the tube way beyond it's max ratings if it shorted that fast, like an open resistor or shorted capacitor.
You should be extra vigilant in looking at every related part and finding the cause before destroying another way WAY overpriced tube, thank you audiophiles very much!

Thats right it caused the new tube to short out immediately. I recapped everything leaving a couple of micas. There are a few resistors there too. C-115 if that shorted it would pull the grid voltage way up. I'll swap that one and check those resistors as there are a few there.

Unfortunately, I'm away from home for a couple of days at work and then I've got to study for my yearly recurrent training early next month. I'll only be able to dedicate a short amount of time at this for a couple weeks.

A 20$ 6CG7 gone in a flash...
--
Matt Davala

[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.

[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!

[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

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.

[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.