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

Michael Taylor mtaylor.tech at gmail.com
Wed Sep 28 20:48:55 CEST 2016


I just wanted to say thank you to all the people who responded with helpful
comments.

It turned out that it had nothing to do with ground bleed whatsoever. I was
actually getting bleed from the SMPTE I/O board and it was polluting the
A/D input circuit. I unplugged the ribbon cable from the SMPTE I/O board to
the CPU board and my MPC is now quiet as a mouse.

Unfortunately, the current online service manual doesn't seem to have
anything for the SMPTE I/O board. Am I missing something, or is it not
there?

Anyway, I am super thankful to have the machine up and running again.

it is easy to take music making for granted when we have access to so much
music making technology from the last 50 years. It is good to be forced to
take a break against your will for a couple of months.

On Sun, Aug 28, 2016 at 7:40 PM, Michael Taylor <mtaylor.tech at gmail.com>
wrote:

> 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
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20160928/270f013f/attachment.html>


More information about the Synth-diy mailing list