Moms yard sale Moog Source find and mystery mod....

[jacques kruseo]

Hello Moog users, new here with some help needed. My mother surprised me with a yard sale find. It's not working, and was home to several mice for years.

It's a Moog Source, with some sort of modification done to it. Inside is a small circuit board that looks to be added on more recently. This is connected to various pieces inside. There's a total of 12 switches that are drilled into the faceplate. Some of the switches appear to be broken inside as they do not "switch" in either direction, and several are completely loose and wiggle.



When I power it on, all I get out of it is a low drone flat-line sound, and nothing else. All of the touch surface responds, but not a single thing changes the sound at all.

I want to attempt a repair, but I really don't know where to even start. I was thinking of removing the add-on board all together, but it is wired into a chip that has pins bend out from it and wires soldered to.

I have some experience in fixing that hardware or replacing parts, but I don't have tools to test chips or boards or anything like that. My only recent experience was replacing 3 divider chips in a Realistic/Moog MG1 a few years back. That also was a clean out of all the old black tar foam.

Anyone out there that could give me some starter pointers, thanks! I have all sorts of pictures, so if there's anything you need to see, just let me know and I'll post what ever is needed.

Thank you all in advance.

[moogsaurus]

Generally with the Sources I repaired,the 6012 DAC chip might be the culprit,when it goes,the oscillators output at a very low cycle - as you described,there's 2 distinct power outputs on the PSU +/- 15V and 5V for the ,DAC runs off 10V,check for that,schematics are readily available online (synthfool should have them)
dont know of any mods for the Source-but very interesting...good luck!

[jacques kruseo]

Thanks for the reply and direction. Ill try and hunt down the schematics tomorrow.

As for the voltage, are you suggesting I test it at the output or input at the DAC? Again, new guy here. I'm not asking you for a doctorate on repairs.

Thanks again. I got so excited to hear this thing after watching videos online, but I know it's a ways out for sure.

[MC]

Before you check anything, make sure the power supply is working and the power rails at all boards are good

[Kevin Lightner]

Before you check anything, make sure the power supply is working and the power rails at all boards are good

This should be etched in granite on the wall of all tech shops.

[moogsaurus]

Check +15V trim R14, -15V at R4, Check Q1 at emitter, set for 10V, loosen the keyboard from the frame and check the 6012 DAC probe on pin 1,if needed set R60 for 0V and R62 for 10V V.
generally on the front the LFO LED should be flashing-if not and its lit solid,generally means a DAC/digital board failure!

[jacques kruseo]

Thank you for the update and help. I forgot to mention the LED is NOT pulsing at all. From the videos I've watched, I noticed mine is lit constantly. Must be the issue.

I appreciate the help and direction.

[moogsaurus]

OK,but check there's 10V getting to the digital board,the AM6012 is a pretty commn chip,Wine Country Productions sell them,but Little Diode on Ebay do them cheaper,maybe pay $25? or if you know somebody with an old prophet 2000/2002 series sampler whip one from the boards (10 inside) the analogue board is pretty reliable-only had to tweak the oscillators range to set, the Source automatically retunes after 5 mins of non playing,damn good synth,still use mine on recordings!