I bought a Roland PMA-5 portable MIDI synth a couple weeks back (like an SC-55 only small and portable).
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Turns out the MIDI - IN port was loose. I figured I'd fix it some day when I worked up the courage, but it was working fine.
Yesterday I got a Roland MIDI-USB adapter cable.
Couldn't get it to work with either my Windows 7 or Linux machine. Figured the cable was bad.
Then, today as I was fiddling with it, trying to get it to work, I would get occasional snippets of sound as I moved or bumped the cable.
So I screwed up my courage and opened the PMA-5 up... it was remarkably clean inside...
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So I got out my soldering iron, which was brand new, only used a few days ago for the first time to solder a USB connector to my Raspberry Pi. Probably not a good one, I got it fairly cheap...
While it was heating, I took a look at the circuit board.
3 of the through-hole contacts looked to have no solder in them. I could wiggle the MIDI port, and the leads would rattle, almost.
So I resoldered them carefully...
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I closed it up, connected it to the Linux box... success! Connected it to my Windows 7 box... more success!
It's interesting comparing how the same midi songs and games sound on it compared to the MT-32.