Mindburner Moog The Source
I was give this synth as a birthday present by my wife. I have always wanted a Source and when one came up on eBay, we took a chance.
It has the usual scratches on the top surface and a few nicks on the walnut side panels, but overall it's nice.
Oh course as soon as I buy this thing, I notice there is a problem. The source display will jump to patch 7 randomly. I had a look on the CPU board and noticed that one of the membrane panel ribbon connectors was attached to a bodged socket. It was encased in glue. I think the heat issue, see below, also contributed to this behaviour.
I replaced this connector with a new 2.54 pitch 6 way from RS components. I cleaned the other 2 sockets while I was at it.
The voice board
The CPU board with new connector fitted . Mostly 74 IC's reliable for the most part. I replaced all the 4016 logic IC's with modern versions. The date code on the old IC's was 1980.These can give problems.
I also found a faulty 4502 with bad gates. This could have caused issues with the panel switches.
Weird bodged trim pot
Source heat problems. My Moog Source gets hot. I mean really hot, like a cooker.
So I opened it up and looked at the regulators and transformer. There are 2x 7805 5v regulators. One for IC logic and one or the display. Plus 2x TIP transistors for the 15v rails mounted on a heat sink attached
to the rear case. I decided to try some small 5V switch mode 7805 drop in replacements. I say drop in as the pinouts are the same, however they don't come with mounting tabs or anything, due to not needing a heat sink..
So I fitted them. Two different manufacturers as I already had the parts.The plastic strips are used to hold them down against the heat sink for robustness.
The result? Well the heat sink was now over 50% cooler and I didn't experience any EM interference as I feared. This can be an issue with switch mode power supplies in audio.
The transformer was still getting warm but not overly. It has 2x 22VAC taps and 2x 7VAC taps, or at least that's what I could measure.
I also ordered a new Source panel from Synhouse. It's ok but colours are not accurate. But still welcome incase of a complete panel failure.