Hello - I recently noticed my BOPP was seemingly missing a ROM Chip from the MPU (see attached picture). I ordered a new MPU board, along with SDB and Lamp Driver board mainly due to free time availability, however I'm curious if someone could help me with what that ROM Chip controlled? I have the schematic, but no matter how much I enlarge it, I can't read the writing on the version I have for the MPU Control Board. (The chip missing is U1)

Subsequent question, is the U1 displayed on the MPU schematic the same as the blown up version for the Lamp Driver Schematic? If so, then it would appear U1 is controlling roughly 16 different lights, all of which would be out on my playfield.

Also, notice the jumper wire on U2 that connects to R14. This doesn't appear on the schematic, any idea what this is for?

Thanks so much!

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Thanks all! Not going to lie, most of those posts are above my head, but I'm feeling better about my new MPU board purchase as it sounds like I'd have to reverse engineer some of the mods made to the machine over the past 50 years.

I cut the battery off last night. Battery removal on these older MPU boards shows up as the very first step on almost all posts, figured I would follow suit. Correct, overall, the board is in really good condition, no leakage or corrosion anywhere. Thanks for the tip about eBay!

Apologies, this specific topic belongs in SS. I have always struggled with where to tag BOPP as it is both SS and EM.

Thanks for clearing that up for me! How does one move or change the tags on my post? Sorry, I'm relatively new to Pinside and am gathering so much information from this community! Am blown away with the responsiveness and helpfulness of others. Thank you so much