It's not too likely you'll see any burn marks anywhere. You'll be looking
for things like a shorted junction on a small transistor, maybe a B-E short
on an output, though not likely, an open resistor, shorted capacitor, etc.

Mark Z.



"jay heldman" wrote in message
news:1an9d.325281$mD.268779@attbi_s02...
yes, i have an analog volt meter. to measure the voltage of center leg of
the o/p transistors which are attached under the heat sync, does one
measure
the center leg to ground in similar manner as how one measured the voltage
of the ceramic resistors (middle leg to ground)?

i can use the ohm-meter to look for a short across any of the three legs
of
the o/p transistors when I pull them from their plug on the floor plane of
the amp.

does it make sense to look for a burned mark on the other small
transistors
in the faulty channel?

Thanks.


"JVC dude" wrote in message
...
Ok so you've established the right channel is running an offset.
As MArk suggests it may not be rail voltage 30-50v but an intermediate
voltage 20v you are measuring.(20v rails would mean a very low power
amp!)
check this by measuring the voltage on the centre pins of the o/p tr'sw.
one
will be +40v perhap, and the other -40v
If this is the case then yes the outputs are probably ok.
Also you can test the o/p tr's (unplugged this time) by looking for a
short
across any 2 of the 3 pins. you will read some conductance across certain
junctions but we are most specifically looking for a short.
Assuming these are ok and that the rails are 40v plus then it really is
just
a case of testing all other small transistors in that channel (6 or 7
nearby) looking for a short or (more difficult to identify) an open
junction.( not measuring like a diode - conducts one way, not the
other).
I would not expect to find just a faulty cap or resistor without a blown
piece of silicon.
If you're going to solve this you need to learn about transistors and how
to
measure them.
personally I always use an analogue meter/ on a low resistance range,
and
one gets a feel for the readings (junctions on B-E B-C) (no junctions
C-E)
(no reverse leaks) (PNP or NPN types)
A digital meter takes a long time to settle readings but does usually
have a diode range that can be useful.
It's here how us time served engineers earn our money- identifying
efficiently the dud bits and not replacing more than is really necessary.

Hope that helps for now.
Report back with your findings

AW