For those of you wondering what I've been up to these days, it's working, going to school, and repairing things on the side for extra cash/trade for things. My most recent conquest was one Yamaha DX7, a synthesizer from the '80s that was used during Michael Jackson's Thriller album, and was also used by Microsoft to make all of their sounds for Windows up until about Win98.
This synthesizer has made me want one - it makes nostalgic noises and has '80s hardware. It's easy enough to work on, but parts are not cheap nor easy to find. Transformers go for about $40 used. So when things break, repairing instead of replacing parts are obviously more cost effective.
This unit came to me from a buddy of mine who traded a violin for it. When he took it home, it didn't power it up. Upon opening it up, he found that the internal button cell had been disconnected from the motherboard.
Repair information isn't readily available online, and the most I could find is that fuses are pretty common for blowing on these, but that wasn't the problem. Some had said that if the battery was disconnected, the unit wouldn't turn on. This was not the case, the internal battery only keeps the non-volatile memory going.
Turns out, the 2-lead power connector coming in from the transformer had desoldered itself from the dc - dc power supply board. So far, I haven't been able to determine if this was physical damage from an earlier intrusion, or if the connection had gotten real hot. The solder pads didn't look overheated, so I'm going to assume physical damage, as the copper pads around the solder joints were actually broken off.
After re-soldering the connections, I plugged it all back together and... nothing!
Turns out, a previous owner had attempted to replace the 7805 regulator, assuming that since the 5v supply coming out of the board was nonexistant, then the regulator was bad. There was a bad connection on the input line of the 7805, so I resoldered it, plugged it all back together, and... POWER!
The button cell used in these had tabs soldered to each side, which soldered into the motherboard. Instead of trying to solder to a standard 2032, or trying to track down a tabbed unit somewhere, I opted to use a AA holder instead.
For those of you tracking down more information on these, here are some Yamaha manuals:
Official Yamaha DX7 owner's manual
Official Yamaha service manual
Yamaha DX7 schematics
This synthesizer has made me want one - it makes nostalgic noises and has '80s hardware. It's easy enough to work on, but parts are not cheap nor easy to find. Transformers go for about $40 used. So when things break, repairing instead of replacing parts are obviously more cost effective.
This unit came to me from a buddy of mine who traded a violin for it. When he took it home, it didn't power it up. Upon opening it up, he found that the internal button cell had been disconnected from the motherboard.
Repair information isn't readily available online, and the most I could find is that fuses are pretty common for blowing on these, but that wasn't the problem. Some had said that if the battery was disconnected, the unit wouldn't turn on. This was not the case, the internal battery only keeps the non-volatile memory going.
Turns out, the 2-lead power connector coming in from the transformer had desoldered itself from the dc - dc power supply board. So far, I haven't been able to determine if this was physical damage from an earlier intrusion, or if the connection had gotten real hot. The solder pads didn't look overheated, so I'm going to assume physical damage, as the copper pads around the solder joints were actually broken off.
After re-soldering the connections, I plugged it all back together and... nothing!
Turns out, a previous owner had attempted to replace the 7805 regulator, assuming that since the 5v supply coming out of the board was nonexistant, then the regulator was bad. There was a bad connection on the input line of the 7805, so I resoldered it, plugged it all back together, and... POWER!
The button cell used in these had tabs soldered to each side, which soldered into the motherboard. Instead of trying to solder to a standard 2032, or trying to track down a tabbed unit somewhere, I opted to use a AA holder instead.
For those of you tracking down more information on these, here are some Yamaha manuals:
Official Yamaha DX7 owner's manual
Official Yamaha service manual
Yamaha DX7 schematics
I mean, Jean Michel Jarre used a Liberation!
