"boardjunkie" wrote in
message
oups.com...
I had this SM-900 rack bass head come in for
repair (fan failed and
caused a meltdown) and someone had already been
in there mucking around
with it. Since there are no connectors for the
pwr amp modules, the
previous "tech" has broken off a couple of wires
from the pcb. The
service manual details one side of the output
section (its a
stereo/biamp head) but not the other, and
they're not identical. There
are 2 20awg brown wires that have been torn
loose. One comes from the
AC leg of the main bridge rectifier and connects
to the corner of one
output pcb, which is shown in the schemo and has
been repaired. The
other brown wire is attached at the opposite pwr
amp pcb and connects
(I assume) to the other side amp pcb. Anyone
worked on this unit and
know where this wire is going? I assume it would
be after the rectifier
diode at the filter cap and they're just jumping
voltage to the other
amp pcb but I want to be sure so I don't have a
smokeshow after I just
rebuilt the damn thing.

The techs at Fender were of *no* help
whatsoever......just tried to
talk me into sending it out to them. No
thanks.....I'm not eating the
time I already have into it.

Also....anyone know the idle current for the
output amps and where they
check it at?

Thanks
Travis

You're lucky. I have one in the shop already
repaired.
However, I need to get offline soon and get to
work.
Email me about exactly what you need and after
work
I'll reply with the info you need. Sometime today,
I'll
reopen it since the schematic is not all that
informative.

Biasing it requires a scope and I'll have to look
up
the procedure or just take a reading
of the idle current and give you that.

Email me at
(sub "psychic" for "science" and "south" for
"sound")

Ed @ Sonic Surgery