Rockwell RD24 not working

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Patrick Souty

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Mar 14, 2026, 5:30:44 AM (9 days ago) Mar 14

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Hello,

I was given a Rockwell 24RD which unfortunately is not working.

The PCB and all components are in perfect condition.

It is fitted with a Rockwell A5901 CA processor, the same as the Microlith 113G whose schematic is available on madrona.ca.

So with some reverse engineering plus this schematic it was easy to check many things on the PCB.

I found that all voltages are nominal but the processor is not running. The processor is probably dead, may be due to MOSFET gates threshold drift over time.

However, surprisingly, the Reset pin #13 is connected directly to the Vss voltage on pin #40 and not through the usual RC circuit found on all the schematics I know, using old Rockwell processor.

So my intention is to implement a classical Reset circuit and see what happens.

Does some one has any advice regarding this issue ?

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