Need some guidance on electrical circuit repair

[Mitch Galehouse]

Hi,

I’m just wondering if you can provide guidance on a small project I’m working on. I’m trying to repair an electrical circuit component for an old electronic air filter that I can no longer find replacement parts for. Here is a photo of the circuit board:

The cylindrical component in the center of the board is damaged. The wire connecting the S1 lead has been vaporized. Do you have any idea what this component is and where I might be able to find a replacement? It looks like it might be some kind of transformer? This board takes 115V AC input at .5 amps and outputs something like 10,000V at low current, I think.

Thanks for your help!

Mitch

[dave walton]

https://en.m.wikipedia.org/wiki/Flyback_transformer

Replacement board:

$168 https://www.ebay.com/itm/152471614917

The circuit depends on providing power to the primary winding at the resonant frequency of the transformer. Probably alternating +DC on opposite ends of a center tap to simulate AC input. If the inductance of the replacement transformer differs too much you will need to swap caps or resistors to get it to start. I’m guessing the 6-pin dip on the replacement board is a 555 timer and is self-tuning. Otherwise it is similar to yours so you can compare components in the picture to find the oscillator circuit. They usually try to run them at a frequency just above the hearing range so we don’t notice the buzz.

I’d be tempted to replace the entire board and be done with it. 

The generic 10kv neon sign transformers (eBay $20) output ac, not dc, and are overkill on the current (high potential pun).

Maybe something like this: $50: https://www.ebay.com/itm/142480503175

Hope this helps...

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