On Wed, 10 Sep 2008 18:29:26 -0700, Tiger Luck
put finger to keyboard and composed:

For the record, the amp is in an Advent 300, which I refuse to let die.

Here's a PDF of the schematics:

http://www.davidreaton.com/PDFs/Adve..._schematic.pdf

The cap that blows is C313. It is a 100mfd 35volt cap It is the filter cap
connecting the negative rail in the lower channel to ground. It is on the far lower
right of the schematic, just above the separate, isolated schematic of the 15 volt
regulator circuit.

The voltage on the negative rail is as it should be. The polarity of the cap was
correct. The corresponding cap in the other channel does not blow. Both caps have
the negative connected to the same source from the power supply and both have their
positives connected to ground. In other words, the negs of both caps are connected
together to the negative rail from the power supply and both positives are grounded,
yet one cap blows and the other doesn't. The cap blew with a sharp crack and the
rubber plug at the bottom blew out. The cap that blew is not shorted. It still acts
like a cap should when measured with an analog ohm meter. I installed another, new
cap of equal value and it started heating up, so I cut the power.

I'm not a pro tech, but fairly knowledgeable and good at logic and such.

Any insights?

Maybe the trace from that channel to the -22V rail is partially open
(ie resistive), allowing C313 to be reverse charged from the +22V rail
via Q317 ???

Just for testing purposes, try running two hookup wires between the
caps in both channels.

- Franc Zabkar
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