Oric Repair: The "Impossible" RAM Failure

This episode is sponsored by PCBWay https://www.pcbway.com
What should have been a relatively straightforward repair of an Oric Atmos, turned into a wild chase for the true source of the problem. Tests kept pointing me in one direction, but my gut told me it was something else.

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Chapters:
00:00 Intro
01:22 Look inside
03:43 Voltages
05:21 Clocks
08:16 RAM
09:17 Diagnostics ROM
12:50 RAM circuit
15:02 ULA
16:08 Power
18:51 Last try
20:38 Testing
21:13 Making sense of things
23:46 Conclusion

Links:
Oric diagnostics ROM https://oric.signal11.org.uk/html/diagrom.htm
Blake's 7 https://www.defence-force.org/index.php?page=games&game=blakes7

Music tracks:
Funky Stars by McKlain https://mcklain.bandcamp.com/track/funky-stars-amstrad-cpc-true-8bit-version
Battro OST by McKlain https://mcklain.bandcamp.com/track/battro-ost
More awesome music by McKlain: https://www.mcklain.com

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