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Gareth Magennis Gareth Magennis is offline
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Default Allen and Heath PA CP power amp


"Phil Allison" wrote in message
...

"Gareth Magennis"

Changed Mosfets thursday, but has now blown 4 out of 6 output devices on
power up. (no load)



** You might have swapped the N and P channel mosfets.

FFS !!!

Always power up gradually with a variac and small value rail fuses after
repairing a blown up power amplifier.

Monitor the AC supply current OR the DC supply current at the same time
too.

It looks from your analysis and the schematic, that the amp should power
up
into its quiescent state with no 2SC/2SA devices present at all.


** Yep.

Now answer my questions:

Are the DC rail fuses connected as shown in the schem ?

Are there really NO zeners on the mosfet gates ?


... Phil



DC rails are as per the schematic.

There are no gate zeners.



Cheers,

Gareth.