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  #1  
Old 07-10-2006, 05:16 PM
frenchy frenchy is offline
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ctc-5 hv problem

Set was totally recapped about 5 years ago by me and haven't had any big problems since then but today I turned it on and sound/tuning is ok but no picture, then 2 or 3 loud pops and I turned it off quickly. I tested all the tubes and look ok. Tried it again and popping did not reoccur but still no pic, I was still getting hv though (pulled the anode connection off the hv rectifier and getting sparking) Now I get zip hv and the hv rectifier doesn't even look like it's lighting up. Any suggestions on where to start? Guess I gotta pull the chassis, arghhhhh. I have to first try to see if can get the hv back before worrying about anything else, I might have screwed something else up while messing with testing the tubes to make it go away, or something croaked later like the flyback but it looks ok visually. Both fuses on top of chassis check ok. Oh well now I have a new project.
One more thing, while I still had some hv there I noticed the hv rectifier had little microscopic sparks visible at the bottom, I thought that was kinda strange. But when it originally acted up today I had a solid state replacement instead of a 3a3 in there anyway so that tube didn't cause the problem. The 3a3 I put in on the second turn-on was doing that sparkly thing (barely visible). thanks
Frenchy

Last edited by frenchy; 07-10-2006 at 05:23 PM.
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  #2  
Old 07-10-2006, 07:27 PM
Bobby Brady Bobby Brady is offline
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Maybe you will be lucky and it is a corroded/broken terminal in the socket of that 3A3. I hope it is not the fly but if it is I hope you save the old one because I think if we can't find a replacement that maybe the old one could be chemically disassembled to reveal the wiring secrets and maybe we could rebuild the old with new wiring! I may try that if my CTC-15 ever goes out.
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Old 07-10-2006, 07:43 PM
frenchy frenchy is offline
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I will put the monster on the bench this week and recheck all the tube placements and wiring etc. and see if anything under-chassis looks like it was arcing or frying, and go from there. Darn it, this was the first time I've tried to power it up after it turned 50 years old, what a letdown.
Frenchy
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  #4  
Old 07-11-2006, 01:15 AM
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kx250rider kx250rider is offline
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Sorry to hear that you had that happen... It's happened to me more than once, and I know how it feels!

It sounds like an arc. If you didn't smell anything burnt, that is. First, check the HV fuse. I think in that set it's near the damper tube, but it's been a few years since I looked at a 5. An arc can also blast the rectifier, or possibly the shunt tube. Was the weather humid??? Those have a problem with the high voltage arcing through pin holes in the CRT shroud to the metal CRT mount hardware. Or, arcing in the cage. If the fuse is blown, replace it and turn out all the lights in the room. Watch carefully with full view, even have another person watching. Turn the set on, and try to see where/if it arcs. Pull the cap off the rectifier and see if the RF is there. If so, then suspect the rectifier or the 30 KV doorknob cap below the rectifier socket.

No promises, but that's where I'd start.

Charles
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Old 07-11-2006, 01:27 AM
frenchy frenchy is offline
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ok thanks I'll update when I have the chassis pulled out and can see if I can even get the HV to come back, arcing or not. It has been hot and somewhat humid here in So Calif lately but I've also had the A/C cranking like crazy for the last month too.
Frenchy

Last edited by frenchy; 07-11-2006 at 01:29 AM.
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  #6  
Old 07-11-2006, 06:47 AM
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yagosaga yagosaga is offline
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Hi frenchy, before putting this heavy beast on the bench:
can you check the hv d.c. current with a hv probe at the cathode of the 3A3? Does the anode of the shunt regulator is red glowing?
There are several reasons for arcing. One of the most fatal is a short in the insulation cone which is placed on the metal cone of the 21AXP22A.
Another reason might be a short in the focus regulation unit. If there is a short, the flyback won't work properly. Check the focus control inside for burnings.
Eckhard
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Old 07-11-2006, 08:10 AM
roundscreen roundscreen is offline
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Hi frenchy.
I would check the heater wire for the 3a3. It could be arcing to the hv cage.
The 5 is a monster chassis.
Good luck
ED
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  #8  
Old 07-11-2006, 10:47 AM
frenchy frenchy is offline
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all the tubes check out on my heathkit tester and glow, except now the 3a3 doesn't seem to light anymore (I could see it lighting up good when the voltage came up to speed before), tried multiple 3a3s so the culprit doesn't seem to be the 3a3. I'm pretty sure I replaced the focus pot when I recapped it. I'm pulling the chassis since it is just too darn hard to see or reach anything on this set with it in the cabinet and I'm already getting myself into trouble doing that. thanks!
Frenchy
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  #9  
Old 07-11-2006, 11:49 AM
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bgadow bgadow is offline
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When I first got my CTC-5 it worked but when I tried it the next day, no picture. The story of how I got it back was long, as I created additional problems along the way. Anyhow, I THINK the initial problem was a short underneath the video board. I had missed it as it was under an IF shield. A terminal strip and attached cap had turned to crispy critters & apparently that killed the raster. At least I think that is what happened. The chances of that being the case here are pretty slim but I did want to relay the experience.
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  #10  
Old 07-12-2006, 06:43 PM
roundscreen roundscreen is offline
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Frenchy
When you get the chassis out check the two black wires next to the red hi voltage wire. {see picture}. Of course this is just a guess on my part but I did have the same problem with the ctc 5 that is at my moms house. I took one out of a newer parts chassis and replaced it. Yes that fly looks like hell, I put pure silicone rubber on it. I clean the fly and then glob it on with my fingers, Nice and thick. It will keep the tire from moving when it gets warm and also helps cool it down a little. A working ugly fly is better than a dead one.
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  #11  
Old 07-13-2006, 10:41 PM
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reeferman reeferman is offline
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At the risk of sounding smug, why don't you use a voltmeter on it? There should also be a resistance chart available in the Sams, too. Do some good old detective work. Good luck.
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  #12  
Old 07-13-2006, 10:56 PM
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Sandy G Sandy G is offline
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Y'know, this is wild-Where else but on AK could you have a problem w/something as exotic as a 50-yr-old color TV, & get a dozen or so replies on how to fix it...from all over the world...Well, at least N. America & Germany...Astounding, simply astounding !!
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  #13  
Old 07-14-2006, 05:03 PM
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holmesuser01 holmesuser01 is offline
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I bet your rectifier socket is bad. I've replaced enough of them on RCA's over the years, including my own CTC-10C.
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  #14  
Old 07-15-2006, 01:10 AM
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reeferman reeferman is offline
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All of the theororists, guessers, second guessors. I would say you have a bad kine-o-derm. Amazing! I think somebody should do a little bookmaking on this one. I still say get a voltmeter and start checking it out!
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  #15  
Old 07-15-2006, 12:25 PM
frenchy frenchy is offline
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I'll pull the chassis Monday, my girlfriends coming over this weekend, first things first : )
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