#1
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rca new vista
i have what looks like a wave that starts at the bottom of the screen and slowly runs up to the top of the screen then it starts again. its very slight but when it starts the picture lifts up on the bottom and there is a little space until the wave passes. any ideas?
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#2
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Sounds like a bad electrolytic filter capacitor. 120Hz AC is not getting properly filtered and is passing through.
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#3
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Yes, textbook bad filter(s) in power supply. The originator of 'The WAVE'.
With a pair of jumper clips and a spare cap you can bridge across the bad one to verify. If its one section of a multiple It would be best to replace the whole thing, it's going dry and the other sections will soon follow. Good luck and be careful. |
#4
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Its the 80uf connected to the vertical output transformer.
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#5
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well that cap in question i changed seem to make it better and that little space on the bottom seems to be getting less and dont understand why if the cap was bad it should be gone right away, from the one i put in originally and the second one i put in. well ill run it.
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Audiokarma |
#6
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Quote:
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#7
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There are several electrolytics that will cause that. I usually use a VTVM on the 500v scale to read for AC at any of the caps. I don't remember what the limit should be, but it's a few volts of AC. Only a VTVM or scope can see it though; not a multimeter of any kind. The needle will zoom up and back right down, and if you find one that shows more AC than the rest, that one is likely shot.
And of course new doesn't mean good! I see more leaky "new" electrolytics than I'd have guessed. Especially those made in the 1990s and shelved. Charles
__________________
Collecting & restoring TVs in Los Angeles since age 10 |
#8
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well my tester only has emissions and good or bad and a short light. i dont know if it covers heater to cathode leaks.
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#9
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Yea, defective new ones will fail fast (infant mortality). If it isnt a cap start subbing tubes.
Pull the 3 IF out and see if it goes away. Start switching tubes with one of your other sets. |
#10
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yea i have alot of tubes to get as spares because i have 6 sets and should have spares for them instead of running to ebay every time i need one. the 1st and second IF tubes i dont have so ill have to start with them, i have plenty of 3rd IF and i tried that one, 6jc6. thanks.
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Audiokarma |
#11
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whats the best way to tell if the auto degauss coil works, ohms check of the coil? there is a new varistor but sometimes it looks as there maybe be alittle discoloring at times on the screen.
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#12
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Easy way: After the tv sits for several hours feel the VDR as power the set up. If its gets warm its working.
Correct way: put your AC voltmeter across the degausing coil and you should see a quick AC spike there when you turn the set on. |
#13
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ok, thanks dan.
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#14
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got it dan thanks.
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