flyback transformer sparks

In a nutshell, the flyback transformer is shot. It's bad, and no amount of high-voltage dope will fix it.

Flyback transformers do fail, sometimes a bit too regularly. They are essentially big coils of wire and over time they may start arcing internally.

A flyback's job is to create the high voltages necessary to make the picture tube light up. The thick red wire going to the suction cup on the picture tube can carry 20,000 volts or more, and that's coming from the flyback. But if the high voltage can find an easier way to get out to ground, it will do so.

Air has a "breakdown voltage," meaning that an electrical arc will jump through it if the voltage is high enough. Dry air has a lower breakdown voltage than moist air; this is one reason why it's so easy to generate static electricity just by walking across a carpet on a dry day. Since air is mostly nitrogen, you'll see a deep blue spark in this case.

High-voltage "dope" is a special putty used to prevent electricity from arcing to the chassis, but as you've witnessed, it can't always work in all cases.

The only option is to replace the flyback transformer with a new one.

I've seen them with sparks running all over the surface on all sides, its due to breakdown not overvoltage. When using HV gloops you've got to be very thorough about getting every trace of carbonised plastic off first, else applying gloop is pointless.

The wire insulation will be shot by now, its beyond help. Sparks turn everything to carbon.

NT

Ooops, other way around. :) You get static buildup in dry air because there is lower leakage and the charge can build up.

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yeah, i was scratching my head on that one too! :)

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You could have an environmental problem. Something (dust, vapor, UV light, high temperature, high altitude, suspended water droplets, etc..) in the atmosphere that is either attracted to the coil and causing some ionization and breakdown, or attacking the insulation on the coil.

Or just a faulty coil.

It is usually better to over react to a corona problem, a little bit of carbon tracking from a previous breakdown can cause the next.

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As I said, I don't want to get sidetracked like last time by fixing the tv.

But I appreciate the rest of your reply.

If you are inclined to email me for some reason, remove NOPSAM :-)

Great. Thanks. That's what I wanted to know.

Everything looked very normal, very uniform, including where the sparks were. I guess I should have tried scraping off the top layer, but maybe

It's strange. I've been using it as a monitor temporarily, and once it sparked every 10 seconds for 4 or 5 times, but most of the time it goes a half hour or hour with no sparks. (It's easy to notice when it sparks, and hard to recall when it doesn't.) When I'm done using it as a monitor, I'll see how it's going. Maybe if it gets worse, I'll take off the silicone and see if I can do a better job putting it on.

If you are inclined to email me for some reason, remove NOPSAM :-)

So, a third possibility. Thanks.

I've done better in the past. It looks something like the Elephant Man's head now. :)

If you are inclined to email me for some reason, remove NOPSAM :-)