My latest project arrived in the mail today. I’ll discuss that in detail in a bit, but first wanted to recap this whole journey. I kind of fell haphazardly into the “buy broke and repair” thing with synthesizers. And I’ve struggled each step, but in general, I’ve been successful and nothing has turned out to be as bad as I thought it was.
The one that started it off was the Alesis. I thought it needed a change of capacitors to solve a voltage situation. I changed them out and it made no difference. but I didn’t break it any worse. And I eventually got it working by cleaning some faders on another board – a solution that was not even on my radar. I just got lucky. That was a cheap thrift store find, so the only worry was disposing it if I ruined it.
Also in my closet is a non-working Roland Juno-Di. I got it for only $80 at a pawn shop in non-working order. So far, I have not had any success in fixing it. In the quest for answers I purchased an oscilloscope. I honestly don’t know what I’m doing with the scope, so it got me nowhere. a local repair shop says the know it’s a chip that needs replaced and they’re waiting on parts to come in. So that’s sitting and waiting.
Next up was an expensive purchase, an Oberheim Matrix 6R, at almost a grand. and it was advertised as needs work. Supposedly needs a new battery and a firmware upgrade. The firmware ship was supplied. I figured I could change the battery easily enough. The end result was that the volume fader needed cleaned and that was all. I swapped the firmware chip easily enough and it’s good to go. I replaced the caps on the display board and the display looked great, but went wonky again when I reassembled it. I’ve yet to take it apart and look further. It’s serviceable right now.
Now for the newest item in detail. Another expensive purchase of the same cost and same family, an Oberheim Matrix 1000 is the latest on the bench. When I first got it and tested it, I got maybe a few notes out of it then it went silent. I popped it open and inspected everything. Things looked ok. I cleaned the volume pot, which didn’t change anything. The problem is, I didn’t know exactly what was supposed to be happening. From the past repair videos that I’ve watched, I understand that the power supply should be feeding a 5v and 12v power to the board. I broke out the multimeter and got measurements of less than half a volt. It sounds impossible that the display would even light up with that little voltage. That’s where I suspected the problem was, so I found a lone seller on eBay selling a used power supply (untested) for a reasonable price, and I bought it.
I then spent a lot of time watching other videos of repairs of the Matrix 1000, none of which had the problem I had. But I did learn a couple of important things. First that patches under #200 might be blanked out on a reset, so they won’t have any sound. And secondly, that there was an indicator when the device was receiving a MIDI signal. Hmmm. With this info, I went back, reassembled the power supply into the device and tried again. Changing to patch 333 still had no sound, but also, there was no indicator light saying it was getting a MIDI signal either.
And the “fix” was to wiggle the MIDI in jack. Then the MIDI signal was received and sound was made. So the problem wasn’t the power supply (but who knows, it may still be. Now I’ll have something to compare it to). But that MIDI jack does need changed. Upon closer inspection, it is loose. And that actually is a problem that was described in one of the videos I watched. They swapped out the jack with a similar jack.
I thought about this over dinner. I don’t know exactly what jack to purchase to ensure the pins line up correctly, and that sounds like a lot of trial and error. What would be better, I think, is sacrificing one of the other good MIDI jacks and swapping it with the broken one. I never expect to use the MIDI Out, but I will probably use the MIDI Thru, so I can pull the MIDI Out and use it.
That’s the plan. I got home from dinner and started setting up the soldering station to remove the jack. However, unlike capacitors which have two leads and are generally easy to wiggle out while the solder is liquid, this jack has seven pins and you can’t heat all of them at once to release it. While the solder sucker did ok on most pins, I still could not get it free. So I did what any frustrated hobbyist would do. I threw money at the problem.
So I already have a multimeter, a soldering station, and an oscilloscope, what’s next? Well, what I’ve seen on videos, which is envious, is a desoldering gun. This device, you put it over a pin, it heats up the pin and solder, you pull a trigger and a vacuum sucks up the solder. It’s the same as the manual solder sucker, but the soldering gun isn’t in the way. That would reduce a lot of my frustration, which I’ve had right from the start. My first repair attempt had me struggling horribly trying to clear a hole that had solder in it.
So that’s where we are right now. What’s on the horizon? There’s a synth sitting in a pawn shop where I had made another purchase. It’s in sad shape, with rust on the base, plus. it’s a synth I already have. But, repaired, it can be worth about $450. I’ll make an offer of $150 and maybe I can bring it up to a level where it can be sold for a profit, or better yet, a trade.
And what purchases can I expect to make during that repair? I expect I will purchase a EPROM writer so I can upgrade firmware. Looks like around $100 on ebay.
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