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#1
08-12-2011, 08:13 AM
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Zenith 12B14C52 Sparky Damper tube
TV works great for a few minutes then the damper tube plate gets red and sparks fly in horizontal output tube 6LB6, of which I have lost 2. Hoping it is not a flyback issue, I will start replacing the disc capacitors in the damper circuit. Shorting capacitors on the boost line are suspect as well. I have R.L Goodman's Zenith service manual volume 2. If you have any ideas, please reply.
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#2
08-12-2011, 10:16 AM
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make sure you replace the damper tube along with Ho tube when you first noticed it. The two work in tandem.
Hope you can find what's loading down the boost. I hate the kind of problems where you have to risk destroying a hard to find part in order to solve a problem.
__________________
Jordan
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#3
08-17-2011, 10:56 AM
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This set saw 14 solid years of use, then sat for 20+, turned on only a few times.
That is when funny stuff seems to happen to our "museum pieces". The problem is intermittent and I wish I could fuse something before I would lose another tube. The original problem was a bad 6CJ3 damper tube, I have several of them, new and old. First suspect is the 2kV 120pf C298. Also the 6HV5A may be to blame. At least with my RCA CTC11 and CTC12 sets, I have 10 of any tube and multiple service manuals.
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#4
08-17-2011, 11:27 PM
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I had a zenith do that It was an open 1meg resistor in the regulator circuit causing the regulator to clamp super hard and load the HOT to death. I would try and fuse the B+ to the damper at about 300ma. Its better to fuse the HOT cathode but that may be almost impossible on a Zenith.
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