PMC-05 ProII Rescue/Upgrade

[djpenguin]

Recently I was helping my brother move, and he gave me a broken PMC-05 ProII mixer. It didn't power on, and it was missing all the knobs and the top (gold-colored) faceplate.

The first order of business was figuring out why it wouldn't power on. A little testing with a voltmeter told me that the power regulator board wasn't supplying any significant voltage to the rest of the electronics, so I began working on a replacement. I decided to use a single adjustable voltage regulator instead of the opamp-based voltage reference design originally used, because I already had the necessary parts.


The mixer being powered by the new design (on the breadboard), with the inoperative original board on the right

Having verified that the mixer worked fine with the new regulator design, I designed a PCB to hold the new design. I wasn't able to obtain a replacement switch that matched the original, so I removed the original switch from the old board and re-used it.


The PCB for the new design with the old switch and a new power jack


It fits!

While I was working on the power supply, I noticed that the mixer internals were configured in such a way that I could fairly easily modify the monitor section and meters to switch between their default (per-channel) inputs and inputs from the master section of the mixer. In order to make this mod, I needed to add some leads to the master section PCB, make a splitter cable, and wire a couple of 4PDT switches.


Splitter cable and one of the switches

While I had the master section PCB out of the mixer, I decided to replace the red LED with a blue one.


Master PCB with new leads (zip-tied to a potentiometer for strain relief) and blue LED

I decided to mount the new switches on the front panel of the mixer; I also decided to add small handles to the front to protect the new switches. I made a template to make sure the holes would be evenly spaced, then removed all the components from the top part of the case.


The top case ready for drilling


Switches and handles mounted


Everything reassembled

For the finishing touches, I bought a used replacement faceplate on eBay, and some rubberized knobs from an electronics store.


All done!

[drzinc]

Great freakin work! It looks and functions better than it originally did.

[pete]

Cool!

At some point I need to take apart my Urei 1601 and repair the power supply section...

[DTR]

Nice job, djpenguin!

[andymunro]

That's brilliant work, I've been putting off just buying replacement faders for my vestax pcv-275 in case i ruin it!

[Mark_Spit]

Incredible work penguin!

Just one question: Did you make that additional board - if so, how?

[djpenguin]

Incredible work penguin!

Just one question: Did you make that additional board - if so, how?

Yes. I used CadSoft's EAGLE software to make the custom footprints for the switch and power jack and lay out the PCB. I made the PCB on an Othermill desktop CNC mill at school.

[Mark_Spit]

Nice!

I remember seeing Othermills a while back and thought they'd be ideal for the scale of work I normally do. However I have no experience with the software.

[djpenguin]

EAGLE is pretty easy to use, and there are a lot of tutorials out there. You just have to jump in.

The best part about using EAGLE with the Othermill is that the milling software (Otherplan) reads the EAGLE board files directly, with no need to export to Gerber.