[sdiy] Does anybody have a BOM for the MPC3000 power PCB and power filter PCB?

[Michael Taylor]

Hey all,

I've decided that it's finally time to recap the power supply on this
MPC3000 due to weird ground noise issues.

The MPC is very quiet when not in use, or when playing back preexisting
samples. When you put it into sampling mode it is quiet until you plug in a
cable and then it has a very loud high pitched buzz. The cable does not
have to be connected to anything, just the act of plugging in a cable
starts the MPC buzzing. Pull the cable out and it's quiet again.

-This has happened in my studio and at the workshop at my job(separate
buildings about 1.5 miles apart).

-This is not transformer buzz or a whine from the inverter(the transformer
is physically silent and the inverter is a separate sound that stops when I
shut off the LCD backlight).

-This issue has arisen in the last six months, it was relatively quiet
before that.

-This happens with no other connections that a 1/4" cable and the
headphones or stereo outs to a mixer(IOW SCSI is not part of the picture
and this happens with or with a SCSI drive connected).

-This sound is present in all new samples that are recorded while there is
a high pitched buzz. You can sample silence, and the MPC will be silent in
playback mode and then you will hear the buzz when you play the sample and
then silence after the sample stops.

-The MPC sequences midi, accesses a SCSI CF drive, and plays back
samples completely normally outside of the sampling issue.

So my two questions are:

Can you guys think of anything else I can do to trouble shoot this issue
besides redoing the PS boards?

Does anybody have a preexisting BOM for the caps on these PCB?

I have the service manual, but the parts listings are cryptic for some
parts and completely missing for others.

Thanks,
Mike
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