Going through the ins and outs of the Lell PSR rhythm synthesizer a.k.a. drum machine made in the last months of the USSR. After a few days of frustrating work figuring out what was wrong, I got it back up and running. Oh my goodness, this was an awesome relief! You think it's gonna be a babysitting job... nothing farther from truth.

Sharing some insights I gained from reading the info (http://www.dubrovenko.ru/ddssite/dshlelsw.htm, https://ruskeys.forum24.ru/?1-0-0-00000041-000-0-0-1344017700 and https://www.dtech.lv/techarticles_lel_psr.html) and my own reverse-engineering work. Also featuring two little mods I did on the unit.

I may be making another video on Soviet chip markings because they're pretty confusing at first but logical if you know how they're constructed.

0:00 Intro and Recap 2:55 Info on the Lell PSR 3:39 Panel Design Versions 5:31 Russian User Manual 7:47 Translated and Annotated By Yours Truly 10:20 COP402 Firmware - Lost? 12:10 Notes on the PSR I worked on 14:30 MIDI? What MIDI?! Ranting 16:06 At the Bench... Again! 17:00 VFD Cover Color 17:30 Fixes on the Control Board 18:00 Firmware Storage and Addressing 21:44 The Diagram of Discombobulation! Control Board Layout 23:00 System Architecture 25:50 Memory Subsystem, ROM and RAM 27:45 Battery Backup Issue 29:48 Unimplemented MIDI Functionality 31:40 Buttons 32:50 It Sounds! 33:25 Predefined Rhythm Demonstration 39:05 Putting It Back Together 40:55 How To Screw And Not Get Screwed 44:10 Bottom Board Mods and Audio Out Circuit 47:10 Closing 49:00 Watch Out For Things Getting In The Way! 51:25 Back Panel Connectors and Battery Compartment 53:10 Testing 55:00 Programming a Song 58:20 Firmware Bug? 59:35 Rhythm Programming? 1:00:00 Afterword

Hey @LOOKMUMNOCOMPUTER and @cathode_gay_tube1312 - you're gonna like it! @momtnz and @GLvintageSHOP might be interested too.

Support me on my Patreon page at https://www.patreon.com/KeritechElectronics or via PayPal https://paypal.me/keritech Instagram - https://www.instagram.com/KeriSzafir Hackaday - https://hackaday.io/keritech

#ElectronicsCreators #Keritech #Electronics