Sochor DRX85 Reverse Engineering - Complete!
Channel: Keri Szafir
Date: 2023-03-02

Another video on the DRX85, this time it's fully reverse-engineered. It took me two weeks to track every trace and component on the pretty complicated board, all done with no computer assist, taking notes on paper and drawing the schematics. Double-checking any WTF while also learning about the inner workings of analog-to-digital and digital-to-analog conversion. And all this insanity was built in 1986 - the same year Challenger crashed, Chernobyl blew up and I was born!

0:00 Intro
2:47 Shine Some Light
7:40 Other Board Examples
9:52 Block Diagram and Panel Overview
13:37 Bypass and Dry/Wet Mixing
14:27 Analog Section - Input
19:50 Echo/Reverb DAC Killer
21:07 Analog Section - Output
22:12 False Bypass?
25:00 It Was Madness!
25:59 Time Circuits
29:47 Changeover DAC Killer
30:40 Time Circuits Logic
33:07 A Trip Down The Memory Lane
35:47 ADC and DAC, Digital Feedback
45:00 Covers Go Back!
48:27 Some Conclusions
50:20 Let's Make Some Noise!
52:33 Thrash Metal Can?

Planning to make another video where I'll go over the inner workings of the digital part. Of course, after I get a grip on it :)

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