The TX81Z has no diagnoseis mode that I know of (but I could be wrong there). What sort of problems are you having? I use one a lot so maybe I can help.
Hi Flippy I'm not TX81z user right now but I'm going to buy it soon ( I have a good deal) .If you can provide me with the spec. of TX81z... that would be great P.S. I know only ..it's a 8 part multi. and FM synth that's all I know .I want more ..
In addition, the TX81z is 8 voices polyphonic It's a 4 operators FM synth. Operator waveform is not limited to sine wave:8 waveforms are available ( may be I'm wrong,I just sold my TX last month)