Grundy NewBrain - Part 5 (Troubleshooting continues ...)

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The Clueless Engineer

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Published on July 24, 2022 11:10:42 AM ● Video Link: https://www.youtube.com/watch?v=tCFSHsf2Vo0

Duration: 24:52

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7

No major progress. Cleaned up more capacitor corrosion, swapped some more chips, noticed ROM link problem ... but still the same issues.

The board was configured for a 8KB and 16KB ROM but I had decided to try "version 2" ROMs using three 8KB 27C64 chips. However I neglected to modify the board for this. Still, it made no change. I did compare the ROM contents of the CD & EF ROMs and they were identical with my original 16KB ROM chip.

It could still be RAM, but I'm not sure whether my replacement RAM is okay ... as there is no space for a socket I want to be sure my replacement RAM is working okay first.

So I'm going to park this troubleshooting for now. There has to be something obvious that I'm missing ... :(