#136
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The fact that you aren't seeing red doesn't automatically point to the red gun of the CRT. You could (and almost assuredly do) have a matrix or demod issue. My CT-100 had problems in the red adder that completely killed any red on the screen; the 15GP22s strongest gun was actually the red gun however.
If the tube was going gassy, I strongly suspect you'd have at least major focusing issues, etc. Get the chassis working first, then worry about the CRT. Even if the CRT is garbage, I'd finish the restoration and wait for a clunker CTC-5 with a good 21AXP22 to surface. There's little point in having an operational CTC-4 without a good 21AXP22, and you'd be throwing good money after bad by putting another 21FBP22 or 21FJP22 in it. |
#137
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Started to replace some tubes. I also tested the tubes I was replacing and noticed that the 12BH7 R-Y Demod tube has a cathode short. This could explain the absence of red. This short didnt show up on the hickok 600a, but it did show up on the WT-100a. The WT-100 has an extremely sensitive shorts test so I guess it was able to pick it up.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#138
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I've been thinking about stealing the 21ax out of the 5 and putting it in the 4. Does anyone have a glass retrofit kit for the 5? I'm not sure it's a good idea really, but I am looking for authenticity.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#139
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I hope you can find a real retrofit kit, but they are scarce. I never found one. I used some CTC-7 pieces plus miscellaneous jury-rigged hardware to put a glass tube in my 5 until I could get a 21AX. Regarding authenticity, there is no visible difference from the front, and you can do it without destroying any part of the 5 (just save a few parts like the plastic funnel and edge magnets in a box), so if/when you get another 21AX, you can always reverse it.
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#140
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Quote:
I have never seen another factory kit. -Steve D.
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Please visit my CT-100, CTC-5, vintage color tv site: http://www.wtv-zone.com/Stevetek/ Last edited by Steve D.; 02-01-2017 at 04:13 PM. Reason: add photo |
Audiokarma |
#141
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that kinda looks like what holds the CRT in my RCA roundie Test Jig.
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#142
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Don't know if it would help, but I do have a spare CRT mount assembly out of something like a CTC-15 that I'd sell.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#143
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Sounds like too risky of an operation. Let's just get it going first i guess.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#144
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I replaced a shorted 12BH7 (R-Y G-Y Demod) and a shorted 6AG7 (Demod driver) tube hoping I would see at the least a bit of improvement. Well there was none whatsoever, if anything the picture quality has gotten worse by just sitting for a mere month. I still have no red which pisses me off since I really thought the shorted R-Y demodulator tube might have given me a hint of red when replaced. At one point I had red. Once I did a recap, I lost it which doesnt make any sense to me. Also I still need to figure out what all the interference associated with the color being present in the picture is all about. While I had the chassis on the bench testing voltages and checking wave forms, a resistor started smoking. It was a 10K 2watt resistor feeding a 285v supply off of the demodulator coil, its value has now risen out of tolerance so I will replace it regardless. Not sure if this may be an issue with the total absence of red. There is also a thick line on the side of the crt when the set it on, doesnt look like a drive line to me. Ive got my work cut out for me and I still have a lot to learn about these sets even though Ive restored two other roundies. Anyone here have any ideas on where i would even begin to look?
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#145
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if it had red at some point before doing a recap, then you should check your work.
also, checking pin voltages is 1st (think you did this early on and there were issues with voltages at CRT pins) if the Purity is way out, then getting good red will be an issue as well. How does the CRT check for emissions and cut off? |
Audiokarma |
#146
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It looks like the 3.58 oscillator isn't running.
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#147
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good point about the osc, I am used to seeing the rainbows in the pic, but that is when its not synced up, could be not running at all. Get the scope and see if you can get a wave form from the color osc.
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#148
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I am pretty sure the xtal is bad then. I mentioned earlier in this thread that it rattled when tapped on. Ill check for waveforms , but ill probably need a new crystal. Does anyone have one? Emissions are weird and somewhat weak at 6.3 but spring to life at about 7.5 volts. But ive known not to trust my crt tester sometimes. It tests good enough at 6.3 to at least produce some red.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) Last edited by SwizzyMan; 02-18-2017 at 06:56 PM. |
#149
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I think Ive confirmed that the 3.58 oscillator is not running. I checked for waveforms on both sides of the crystal and I got nothing at all. Keep in mind I took this measurement with color control fully up, but not connected to the CRT so no HV or anything. I think I have a bad crystal.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#150
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Rattle in a crystal sure is a bad sign. These are easily obtainable (eBay etc.) but beware most are for transistorized TVs, a larger earlier one is what you want. Usually these are in the HC33 size case.
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Audiokarma |
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