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Greetings all,
Today I was measuring the plate voltage (pin 3 of one of the 6L6's) in a hot rod deluxe, when a small but very hot flame jumped from pin 3 on the board. I quickly turned off the amp and unplugged.
It appears damage was done to the pin 3 pad on the board. After things cooled down, I checked the trace and it was still connected on the board, but jiggling the pin caused it to break connection.
I fixed the board by cutting the trace from the OT to pin 3 and jumpered the connection directly from pin 3 to the spot where the blue primary OT connection is located with a wire.
My take on what happened is that either the eyelet on the board was bad, and touching the pin to measure it caused it to break the connection, arc, and flame, or the solder connection on pin 3 was cold/bad and touching it moved it causing the same.
I'm curious if anyone has any other thoughts on what could have caused this. In all the amps I've had my hands in, I've never had something like this happen.
I also checked the OT primaries and they are still good. The tube actually looks fine, but I'm erring on the side of caution and replacing them. I checked the two diodes (CR4/CR5) and they are fine, no other components show signs of damage visually.
Any other components I should check for damage?
I did install an older set of tubes, rebiased, and it seems to play fine.
Today I was measuring the plate voltage (pin 3 of one of the 6L6's) in a hot rod deluxe, when a small but very hot flame jumped from pin 3 on the board. I quickly turned off the amp and unplugged.
It appears damage was done to the pin 3 pad on the board. After things cooled down, I checked the trace and it was still connected on the board, but jiggling the pin caused it to break connection.
I fixed the board by cutting the trace from the OT to pin 3 and jumpered the connection directly from pin 3 to the spot where the blue primary OT connection is located with a wire.
My take on what happened is that either the eyelet on the board was bad, and touching the pin to measure it caused it to break the connection, arc, and flame, or the solder connection on pin 3 was cold/bad and touching it moved it causing the same.
I'm curious if anyone has any other thoughts on what could have caused this. In all the amps I've had my hands in, I've never had something like this happen.
I also checked the OT primaries and they are still good. The tube actually looks fine, but I'm erring on the side of caution and replacing them. I checked the two diodes (CR4/CR5) and they are fine, no other components show signs of damage visually.
Any other components I should check for damage?
I did install an older set of tubes, rebiased, and it seems to play fine.
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