Share your knowledge on these two classic MPCs
By namesake_audioresearch Sat Nov 13, 2021 10:08 pm
Gday,

I've been working on repairing an MPC3K - namely the PSU. I thought I'd repaired it, all of the voltages from the ribbon connecting to the CPU board are reading correctly. However, when I plug the ribbon into the CPU board and turn on the device, fuses F3 & F4 blow instantly.
The MPC is coded for America, and the fuses in F3/4 are the correct amp (800mA) but 250v instead of 125v.
I've disconnected everything from the CPU board, and it still blows (doesn't when the PSU is turned on while unconnected).

Is there components on the CPU board that could be drawing too much current? Anywhere I should start hunting?

Thanks in advance!
By namesake_audioresearch Tue Nov 16, 2021 8:12 pm
Update: I've fixed the fuse issue - found a grounding problem that's been resolved.

When switched on there are no LED's on or text/backlight. Upon further inspection one of the +5v when measured from the PSU ribbon is at 10v, while the other is fine. Seems bizarre as they both come from the regulator which is measuring fine?

Any assistance would be greatly appreciated!

Cheers