On Tue, 17 Nov 2009 14:51:30 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Jim Lesurf wrote:
In article , Dave Plowman (News)
wrote:
Had a quick look today. There are two stereo effects amps which appear
the same - both with accessible connectors to their PCBs. Unplug the
one marked rear and the amp stays on. Plug it back in and unplug the
other and it trips.

Well that may offer two easy 'solutions'.

One is to simply use it with the duff board out of circuit. :-)

That is one way. ;-)

The other is to compare voltages, etc, between the two to help find the
fault - if you can keep the thing working for long enough without the
protection making this impossible! :-)

I've downloaded a PDF of the service manual for $8. The offending power
amps are strange (to me) in that they have 3 HT rails. +/- 35v for most
and +60v for the output pair.


Could be class H. This is a power saving scheme that uses two power
rails - one low for normal listening, and a higher one that gets added
on when the power requirement is higher.

If you want to post the schematic somewhere I dare say that some (at
least) of us here can help you fault-find.

d