Where is the board revision located on the PCB? My voice boards have "OBERHEIM 1810D" etched on them. I couldn't find any other useful marks.
From what you are saying can I glean that I have the latest firmware for my voice boards, because the synthesizer would not work properly with Revision 1.6?
I only see the Voice Processor Malfunction message when I disconnect the clock signal from the main board to one of the voice boards.