Oberheim OB-Mx Preservation Page

Schematics

The schematics were provided by Mark Glinsky of Manual Manor.

• Voice Board: CPU Section, CV Demultiplexing, Voice A VCO, Voice B VCO, Voice A Processing, Voice B Processing
• Master Board: Digital Section, Analog Section
• Front Panel

ROM Images

I'm not sure what the exact differences are between the various software versions, but I do know that the older versions of the master board O.S. blow chunks. I'm including older versions here for posterity. They're straight binary files. Many thanks to Tom Collins of GTRI for making the images for me; few people around the department still had equipment that could read them! Tom included some text files comparing the different versions; I'm not sure how useful the comparison files are, but here they are anyway.

Does anyone have an 80C198 disassembler?

• Voice board software: June 14, 1994, Dec. 5, 1994; Comparison of Dec. 5 and June 14 versions
• Master board software: Version 1.04, Version 2.00; Comparison of V1.04 and V2.00
• Calibration ROM and instructions (courtesy Tom Virostek) - The calibration procedure is pretty complex and requires a scope (and preferably the voice board extender card that lets you get to the board while the unit is on). The OB-Mx uses some digital pots with built-in nonvolatile memory. I had always assumed that these were recalibrated upon booting up the OB-Mx, but it turns out they are set in this calibration procedure. I suspect that a lot of errant voice boards that are out there just need recalibrated.

Patches

Anyone have patches they want to share?