A returning customer of mine found a vintage Soviet drum machine and asked me if I was willing to recombobulate it. I took the challenge... and this is the first part of a little series of insights on this interesting device. It's a microprocessor system with RAM, ROM, VFD, keyboard, DACs, whatnot... Given the political & economic situation, it's interesting to go through it. It's pretty typical Soviet electronic engineering with all the ICs using Soviet rather than Western markings, so I had to do some research to find the equivalents and determine their purpose.

A lot of work has been done off the camera, and it was a great learning opportunity too. Who would have expected that I'd not only have to program EEPROMs, but also deal with programming voltage level mismatch and make a level shifter to get it to program at all? That's engineering, that's what I do for a living... Sorta.

0:00 Intro 2:44 RTFM! 4:50 Overview 9:25 Discombobulation 15:12 Bottom Board Top View 18:15 Getting To The Top Board 19:30 Keyboard 20:35 Top Board 21:30 Soviet Tact Switch Test 24:33 Diodes Gone Wild? 28:37 Semiconductor Perplexion 30:00 Adding a Missing One? 32:40 Recombobulation 36:40 Testing 37:30 DACs 48:25 ROM Rot 49:10 Bottom Disassembly 53:27 Bottom Board Underside 56:31 Afterword

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