#61
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Haven't had much time to work on it. The anode lead is about 6 inches to short to make it to the other side of the CRT.
As near as I can tell, there's no resistor in series with the anode lead or in parallel with the 1B3 rectifier tube filament. When I find time, I'll try to run a new anode lead. The only way to get at that area is to take the HV box off which is not so easy since the flyback is mounted to it. |
#62
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Here it is stripped down.
I get about 0.1 ohms from the anode cap the the rectifier base, but I'll try replacing the lead anyway. Flyback close up. The shiny goo around the HV lead is some RTV133 I applied to reduce the odds of it snapping off. HV rectifier area looks clean. I'll try using a solid state rectifier as suggested. Last edited by bandersen; 10-14-2014 at 02:51 PM. |
#63
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#64
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[QUOTE=bandersen;3119451]I recently won a little assortment of vintage TV parts on ebay and it including this air core flyback. The part # is different but it sure looks like the one in the Capehart and it ohms out very close as well. Might as well give it a try.
Bob, you certainly have nothing to loose and a lot to gain! Good on 'ya, Mate! |
#65
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I think I'd have me a peek under that electrical tape before applying power.
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Audiokarma |
#66
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Nothing wrong with using a temporary alligator clip jumper lead to lengthen that second anode wire. I've never had the HV arc through the insulation to the dag, chassis, or wherever else it may be contacting or draped, even with cheapies.
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#67
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I'd be more scared to risk removing it absent any other justifiable reasons for investigating underneath. Obviously I'd spend a good few minutes going over the whole thing with all the bright bench lights on and with my mag-visor for signs of trouble.
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#68
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I don't like those wafer-type sockets, especially on high voltage. They can have secret interwafer problems. It would be a valuable adventure to change them to good new molded ones, even ceramic ones if you're paranoid like me.
__________________
Reece Perfection is hard to reach with a screwdriver. |
#69
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I finally got back to working on this chassis
The ceramic HV cap on the damper tube has been replaced and a new HV anode lead installed. I also installed a genuine Farnsworth 160AR CRT I stumbled across on craigslist. It had no trace of any external coating but I did fine a ground spring on the chassis so it probably should have one. I went with a temporary one made from aluminum foil and tape If I get it working, I'll coat it with some Slip Plate. The old hardened tape was replaced wit some cloth tape. While I had the brackets off, I finally found the chassis revision number - C-281. TIme to fire it up again. |
#70
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HV is around 10kV. I'd rather see 11 or 12, but should be plenty to produce an image.
Sure enough after a lot of fiddling with the trap magnet, I got a raster. I get occasional arcing. I think it's my temporary aluminum dag isn't making good ground contact. I'm gonna let it run a while and see if any problems crop up. If not, I'll give that CRT a proper coating |
Audiokarma |
#71
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Sooooooo, are we listing the HV lead as the culprit? Glad to see that you climbed right back up on this horse and got rewarded with some success.
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#72
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Did you connect that HV lead before the power up, or was there a brief lightning show before you noticed?
__________________
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 |
#73
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Quote:
Yes, I did remember to connect it up |
#74
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My Sencore CR70 has the meter right at the edge of bad in the HK short position. It typically arcs once or twice on power up the settles down.
I went through the centering and linearity adjustments and it's looking pretty good. I'll install an isolation type CRT booster if I can find one Meanwhile, I decided to go ahead and coat it with Slip Plate. I'm quite happy with the results |
#75
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Installed the recoated CRT and did all the ion trap, focus coil linearity etc adjustments again. It's playing well but still get the occasional arc in the CRT on power up. Will try an isolation type booster when it arrives in a couple days.
Meanwhile, the picture isn't quite as sharp as I think it could be so I'll try a video IF alignment. It used a staggered tuner IF and it's a an easy procedure. Feed an RF signal into the mixer tube shield an peak each coil to the specified frequency frequency. Last edited by bandersen; 02-23-2015 at 12:59 PM. |
Audiokarma |
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