Share your knowledge on these two classic MPCs
By fatbit Sat May 21, 2022 9:49 pm
Hi MPC experts! could you please help me with this issue?
My MPC60 stopped working :shock: while I was playing some external instrument through MPC60 sampling input.
At some point, I started smelling burnt. The sound I was monitoring fainted for a couple of seconds ( lack of bass and white noise) and then stopped at all.
Now, when I restart the MPC, the entire screen turns black or shows some black squares, (depending on the backlight knob position) then some lines get randomly cleared. Nothing else happens and panel LEDs are off . I can still hear the usual low-level inverter noise though.

I have already checked the flat cables and other internal connections but no luck so far.
I suspect a thermal issue as I was using the unit inside of some kind of drawer, also I had an ACARD SCSI IDE converter that seems to run a bit hot ( which I have now disconnected)

Do you think this could be related to broken PSU capacitors? I do have the service manual but I could not find any procedure on how to measure output voltages. Is there any way I can check?
Also, I'm a bit suspicious about the "white noise" issue just before the unit failed completely.
Could it be related to the soundboard failure?
I have some spare boards (but I'm not sure they are in working condition) and I will try to do some swap tests.
If all boards except the CPU board are disconnected, is a working unit supposed to boot?

Thanks in advance for your help!
By LoopTheCrook Sun May 22, 2022 9:45 am
I’d first check the fuses if you don’t see anything suspicious.
By fatbit Sun May 22, 2022 7:12 pm
Hi LoopTheCrook

Thank you for your reply! I have checked all 4 fuses with a tester and they are fine.
One thing that I noticed is some yellow/brown material in between capacitors C4 and C5.
Not sure if this is just glue or if there is an issue with those.
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By mr_debauch Mon May 23, 2022 8:13 am
i might suggest you replace those because it can't hurt either way.. when caps blow it can have that burning electronics smell.. it might just be that. It could have been leaking beforehand or damaged and while in use it finally shat the bed.. it's quite possible.
By fatbit Mon May 23, 2022 11:25 am
Thanks Mr debauch!
Any suggestions on cap brand/model?
Also, I'm struggling to understand the service manual, I see those caps are called C4 and C5 in the power supply board drawing, however, I cannot find any reference to C4/c5 in part list tables
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By NearTao Mon May 23, 2022 4:23 pm
C4/C5 likely means the location on the PCB board, and not the brand/model...

You should be able to see what the specs are for those two capacitors though...

If you're uncomfortable with the work, might be worth finding a local service tech... cap replacements are pretty standard, and those two do look like at least one of them leaked... I doubt that is glue.
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By NearTao Tue May 24, 2022 8:07 pm
fatbit wrote:Thanks NearTao

I should be able to replace them but my concern is more about some obscure specs (i.e. "ripple current' )
I have ordered a couple of those, I hope they will be fine:
https://export.rsdelivers.com/product/p ... dc/7396828
10v 12000uf capacitor instead, seems a bit harder to find.

I will let you know once I replaced the 25v 1000uf c4/c5 pair


10v 12000uf to 25v 1000uf sounds like a massive difference to me, and I would not suggest that varied a difference. You really should make sure you get a 10v capacitor, and see if you can get something that is around the size of the 12000uf, otherwise my expectation is that you're going to fry your MPC by over volting it.
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By NearTao Tue May 24, 2022 8:10 pm
Not sure why you had such a hard time, a quick google search got me

https://www.ebay.com/itm/12000uF-10V-Large-Can-Electrolytic-Aluminum-Capacitor-12000MFD-10VDC-12-000-/142279989750?_ul=IL

or this

https://www.mouser.com/c/?q=12000uf%2010v

Hopefully that helps you find what you are looking for.
By fatbit Wed May 25, 2022 6:46 pm
Hi NearTao

Let me explain, My initial plan was to replace C1 ( 10v 12000uf ) and C4/C5 (25v 1000uf )
Mouser has a Wurth 10v 12000uf but it is not immediately available ( at least not here in the EU)
The eBay link that you provided is for a snap-in capacitor which might require some additional adaptation effort compared to a regular radial type with long pins
For now, I will replace C4/C5, if this doesn't help, I will order the Wurth one or another brand with the same specs.
By fatbit Sun May 29, 2022 10:10 pm
Unfortunately, C4/C5 capacitor replacement and cleaning of all boards did not help.
Waiting for a 10v 12000uf capacitor to replace C1 now...
By fatbit Tue May 31, 2022 8:34 am
My MPC60 is working again! :-D
The only thing I did was replacing c4/c5, unplug all the boards, wash them with an isopropyl-based product, and reassemble all parts.
At this point, I'm not sure what was the issue, how was it solved and how long it will last :hmmm:
Any thoughts?