I have an Oberheim OB8 that worked when I got it. Then the tune button started "locking up" the synth. But a power down would fix it. Then it started locking up when I would play too many keys. Again a restart would fix it. This happened more often when it had been on for a while and was therefore warm. Then it just gave up alltogether. Lights come on, but don't respond properly, and there's really no discernable sound, just very faint background nonsesnce that changes slightly when you press down keys.
Has anyone else experienced this? or have a suggestion of where to start? I live near Milwaukee, Wi.
Most likely power supply related. I have an OB8, OBXA, OBMX and Xpander... all of them have had their power supply's overhaled/rebuilt. It makes a world of difference. I also use a Furman AR1220 Line Regulator to keep my analog synths at 120v steady. That helps too.
All of that OB range benefit immensely from a full calibration.
The service manuals go through the procedures to calibrate the power supply, m/b, mod section, filters, vcos etc.
The other things that can make a huge difference are cleaning all the internal plugs with deoxit. They have large metal pins that develop a thin while film from oxidisation that inhibits the electrical flow.
There are also unfortunately heaps of socketed ICs, particularly in the Xa and OB-8. If you carefully remove them with an IC puller and clean the pins with deoxit this can make an enormous difference as well.
If that sounds above your capabilities get it serviced by a real technician.
The old OBs can be moody but once figured out they are very reliable. I have an OBXP that is super consistent. My OB8 can be moody and i believe it is completely to do with old molex / ribbon card connectors. These parts don't always age well and if your synth has a loose or sloppy chassis you can get more of these issues. I have OS B5 w/ factory midi and i get hung notes once in a while but no crashes.