On Saturday, April 19, 2014 at 3:05:50 PM UTC-7, nixiebunny wrote: > > There was also a carbonized spot to the left of the transistor,... I don't > know which was the chicken and which the egg. > > Over the years, I'ved had several experiences with charred PCBs. The most notable one was on power supply board, that was part of a larger system, that our company made. It looked like one of the tantalum caps ignited, and managed to get the epoxy fiberglass PCB burning, too. I could stick my hand thru the resulting hole ! This happened out in the "field", so how it occurred is largely speculation. One of our service techs brought it in. That board had several large 100uf tantalums on it. 94V0 rated, too :(
Another incident involved a 100W Marshall tube amp. I repaired it for a friend. When it came in, the power supply was being overloaded. It was too new of an amp, to already have bad caps. Found a short between the anode pin and one of the heater pins, of one of the EL34 tubes. The heater is grounded on this unit. Its not left floating. The short was caused by carbonized PCB between those pins. Don't know what initially caused it. I blame a small critter, like a roach. The owner's housekeeping skills aren't the best. Fixed it with an X-acto knife, by carving a slotted hole between those pins. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/b23af398-8b00-4850-8de7-b7508b99db28%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
