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 Post subject: Arc from 1B3 plate cap lead to flyback cage
PostPosted: Oct Sun 29, 2017 6:17 pm 
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Joined: Jul Sun 24, 2011 2:57 am
Posts: 21
Working on a Zenith round tube TV. Fired it up for the second time. After it ran for about 30 minutes we heard a noise. I saw a blue arc inside the high voltage cage. After opening the cage it appears the arc was jumping from the plate cap lead of the 1B3 tube to the inside of the cage where the flyback live. Why is this happening and what can we do to eliminate this problem? Thank you.


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 Post subject: Re: Arc from 1B3 plate cap lead to flyback cage
PostPosted: Oct Mon 30, 2017 1:55 am 
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Joined: Aug Thu 12, 2010 6:25 pm
Posts: 123
Location: Durham, NC
It could must be that the wire to the 1B3 cap is very dirty, allowing the HV to find a lower-resistance path to ground (the cage), or the wire might be damaged or cracked. Cleaning & inspecting the wire (and cap) is a good idea (also the inside of the cage if it's very dirty). The wire may need to be replaced if the insulation's cracked.
It also could be that wire is out of position (some sets have an insulated tab to keep the wire away from ground points. And it could be that some of the components in the HV cage have been moved during previous repairs or in shipping. In all these cases, a judicious repositioning may be all that's needed.
Years ago I repaired a similar arc in my CTC-7 color TV with a liberal coating of "HV Dope" on any cage surface that was near the HV rectifier. A brute-force technique perhaps, but it worked for me for several years.
Remember to discharge to ground any HV wiring you're going to be working on. Safety first!

_________________
Mark Nelson
A collector of TV signal boosters and UHF converters -- God help me!
tv-boxes.com


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 Post subject: Re: Arc from 1B3 plate cap lead to flyback cage
PostPosted: Oct Tue 31, 2017 5:31 pm 
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Joined: Sep Fri 07, 2007 2:27 am
Posts: 4915
Location: Grand Chute, Wisconsin
http://www.videokarma.org/showthread.php?t=269703


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