From Michael E Caloroso Sent Sun, Mar 4th 2018, 07:07
From Michael E Caloroso Sent Sun, Mar 4th 2018, 07:07
I had restored a Memorymoog Plus for a client and the last mile was a challenge. Autotune wouldn't. It would report "6 TUNED" but none of the voices were tuned. When the machine was cold, the C7 routine would report back legit numbers, then they would be all zeros. Other symptom - random crash with loss of patch memory. Great, a temperature failure that is intermittent - the most fun of any debug jobs. That initially pointed to a bad RAM but that turned out not to be the case. After confirming the path from voicecard to autotune circuit, supporting TTL/CMOS, CTC, cabling and interconnect, I finally found a surplus MOSTEK Z80 I had forgotten about... and autotune is WORKING. The original Z80 must have a bad register on the substrate. What threw me off was the rest of the synth was working (except for the random crash). That is a failure mode that none of my bench equipment could had picked up. I've been doing this long enough to NEVER rule anything out, even the CPU that I least expected to be at fault. The MOSTEK part is for all practical purposes a Zilog part. In the early Z80 days, MOSTEK was one of the fab labs that Zilog licensed to make the Z80, until Zilog could afford their own fab lab. Had the unit running C7 for three hours and can't get autotune to fail now. Lesson learned: just because the MM reports "6 TUNED" does NOT mean that autotune works. Sent from my iHighFive, MC