B1 has died

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How odd, my B1 has died, both channels at the same time.

To recollect, this build uses the PSU (SALAS Shunt Reg) from the DCB1 but uses a clone of the original B1 for the buffer.

It was working flawlessly and had been for several years.

I've just completed a Pearl 2 project which works perfectly directly driving my Aleph 4 - so no problems there.

I decided to add the B1 as a volume control and it's died.

I've tried the original CD source and the B1 is definitely the culprit.

I just can't believe that it's coincidence that the B1 has been killed by the Pearl 2.

This post isn't about "What is wrong", it's more about "Why"
 
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Just for reference, a mosfet will be instantly destroyed of you apply 28 V gate voltage. For JFET's I have no personal experience to destroy.

The reason why I know about mosfets is that datasheets only say max ± 20 V but when do I break the fet and what kind of failures do I get? More than 26 V = no mercy.

Yeah, and at least one member has encountered a large turn-on thump:

http://www.diyaudio.com/forums/pass-labs/156397-pearl-two-130.html#post2828745

Perhaps the OP can try measuring and see if that might be an issue.

Dennis
 
OK, I've finally had a look at the B1 and I'm baffled.

PSU is fine.

Both NFETs on one channel are fine.
 

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