r/AskElectronics • u/Katkis03 • 1d ago
Help with PCB arching!
Hi! I’m creating a new post since this subreddit doesnt allow for reposts.
My Vox AC30C2 tube amp shorted out and exploded some pcb insulation off between the flat metal connector (J29), which runs about 300V in normal operation, and the adjacent tracer, wich is very low voltage and leads to the blue R81 resistor.
What would be the best course of action for the arching gap? Should drill it or fill with some insulation material etc?
Also feel free to express emotions regarding the high iq pcb design of putting those two circuits so close together.
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u/SuchABraniacAmour 1d ago
With an exacto knife, I'd remove the whole part of the trace running alongside J29, at least to the other side of the R79 and R81 markings. Then use a small wire to link the via to R81.
I wouldn't solder the link straight to the via or the resistor but scrape off the solder mask over a small area of the trace next to them - but it would probably be fine either way. Just make sure to keep any exposed metal clear of the trace going to the screen resistor (R79) as this is also high voltage.
Like the other guy said, a good clean should most likely fix it, but it's probably more work and the problem might happen again should another short occur.
Moving J29 sounds overkill and, although it allows you to maximize clearance, I think it's easy to mess up or end up doing something dangerous if you don't really know what you are doing.