While I've managed to order a repair kit directly from QSC, they keep
urgently pressuring me to send the amp in for recalibration.

I am replacing the chopper transistors, Q1-Q4 (Q2 is what failed) that drive
the primary of the transformer and you can find this circuit on page 12 of
this schematic, available from QSC's web site:
http://www.qscaudio.com/support/libr...werLight%20Ser
ies/pl6.0PFC.pdf

Frankly, I don't see where this non-linear device, replacement of such,
would necessitate a recalibration of the controller, since this is simply a
binary (on/off) process, chopping pulstating DC off the input rectifiers and
producing the initial 180KHz powerwave that gets split up and filtered on
the secondary.

Are the variations among the same part number IGBT so great that a factory
recalibration of the entire unit be performed, using "proprietary test
equipment and procedures"?

My impression is that there is little to nothing to adjust for--I'm just
replacing a switch with a new switch. Performance should be the same. Am I
missing something?


--
Best Regards,

Mark A. Weiss, P.E.
www.mwcomms.com
www.basspig.com
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