Re: fender m-80 pops and buzzes

j327681@xxxxxxxxx wrote:
i got an old fender m-80 solid state amp (circa 1991) that pops loudly
when i plug in my guitar and buzzes when i take my fingers off the
strings.

You likely have a floating ground ... loose connection(s) .

i took it apart and had to replace the two input jacks... they are

typical fender SS crap ...

the input jacks i couldn't resolder because after i took the original
off, some of the copper on the PCB came off, as did most of the metal
rings around the holes, so there was nothing left to solder to.


depending how the chassis and front panel are ,
you can likely install regular panel style quality 1/4
jacks then wire them directly to the circuit ...
This requires some skill and an experienced soldiering technique.

-> Note .. when a pad is lifted (missing) from a PWB, you
can manually rewire/recreate the traces using solid
wire ... and creating fed through pads, and solder wire
to appropriate endpoints ... .. then super glue the wire. This takes time, patience !

( I use to repair PWBs in a computer manufacturer environment I have
quite good soldering skills)



is it vital to have both input jacks wired into the circuit?

generally speaking .. no. there is generally a low and high input.
High is generally used for guitar, and generally used with
the gain control. Pick on you what to work and concentrate on that.

could
that cause the spark/buzzing/popping? what else could cause this? i've

since some of the copper strips came off the circuit board, could i
just solder some jumper wire to connect the points?

yes ! .. may likely where most of the noise is from .. BUT your
mileage may vary. Loose connection ,, cheack any ribbon cables ..
the pins have have loosen and need spread apart to sit better in
the female end.


Is the amp quiet when nothing is plugged in ?
typically, with nothing plugged in the input jacks,
the signal path is grounded .. so there should be quiet.




thanks


can you read schematics ? may be worth getting one.

can you post photo of the guts if you need more help ?


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