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Korg/Univox Mini-Pops SR-120 troubleshooting
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Korg/Univox Mini-Pops SR-120 troubleshooting
So I've got an old SR-120. It was barely working when I opened it up to try to fix it. The corner of the board was snapped so I wired a bunch of jumpers to fix the diode matrix. I replaced a few filter caps while trying to get rid of a 60 cycle hum and then all of a sudden I don't get any sound. I can hear the amp scratching if I play with the volume knob but no patterns play.

I'm checking voltage going to the ROM IC. I'm getting the appropriate 12v supply and the -5v supply is working but the +5v supply is only at 2.8v. Ive got a cheap DSO that I'm using to scope the outputs of the ROM chip and I see blips in time with the patterns but the voltages are lower and time shorter than what I would expect to activate a trigger.

I found a user and service manual here:

Should I go ahead and replace the C1317 transistor in the power supply. what else might be my issue.

I was hoping to install some trigger inputs into the machine as well as some individual outputs so I can use it with CV sequencers.
Well, that’s great. For some reason when I used the URL tag for the hyperlink it left my whole post blank. So I’ve been sitting here hoping for a reply when everyone else just saw a blank post. In my preview everything was showing up fine but not in the published post. Oh well.
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