C0770523-001 Rev.D - Memory upgrade + other mods

STFM motherboards.
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AndrewB
Posts: 1
Joined: Tue Jul 13, 2021 3:23 pm

C0770523-001 Rev.D - Memory upgrade + other mods

Post by AndrewB » Tue Jul 13, 2021 4:17 pm

I found this board in a 520STFM unit.

The board appears to be from a 1040 and appears to have been upgraded to 1.5MB. The bottom row has 16 x TMS4256 chips. The top row appears to have been upgraded with 16 x MB81256 chips.

Some other mods appear to have been done:
  • Extra cap top left of memory row.
  • Extra chip and A/B switch added to board near drive. Chip is glued down so can't see what it is.
  • Wire from Video section to modulator. Might be stock.
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