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Macintosh LC TechStep Tool Troubleshooting?

Posted by: danifunker on 2026-07-20 11:29:14 Greetings everyone! I have a known bad Macintosh LC (1). Recently a friend lent me their TechStep tool to help diagnose the issue, but I don't know what it means. It seems that the Power Supply and CPU are being picked up correctly, the ROM works correctly, but everything else is failing. It can't seem to pickup the RAM installed. The whole board has recently been recapped and I'm using a known-good recapped power supply as well. I tried putting in a stick of RAM and tried it with the RAM removed. Does anyone have any hints for me to proceed with what might be wrong with this?

Posted by: feltel on 2026-07-23 12:19:44 I'm in the same boat as you. I'm also working on an LC logic board which doesn't see any RAM at all, according to the serial diag. I checked every related trace, swapped the multiplexers and also one RAM chip I thought I diagnosed as possible bad chip.

Posted by: danifunker on 2026-07-23 12:54:23 Interesting. Maybe it’s somewhere else on the board then that we’re missing?

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