I found some schematics that can help:
http://atariusa.com/Famicom_Schematics/ ... matics.pngI can disassemble a FC-UNROM-02 (i think it's this revision) board and post detailed pictures here, if you can wait a a couple or days, maybe up to some weeks, since I'm on a vacation trip now.
But the "generic" instructions are:
- Find the unused OR gate of the 74'32.
- Find the unused input pin of the 74'161 (usually it's pin 6, but it's good to check).
- Find the unused output pin of the 74'161 (usually it's pin 11, but it's goot to check).
- Disconnect any connected input/output pins of the unused gate of the 74'32 and the 74'161. Sometimes, the inputs are tied to +5v or GND.
- Connect the unused 74'161 input pin to D3.
- Connect the unused 74'161 output to one of the OR gate's inputs.
- Connect the other OR gate's input to PRG A14. Do a little check and you'll find some pins on the same IC already connected to that.
- Connect the OR gate output tho your ROM A17 and you're done.
I'm not sure of what pins exactly you should disconnect and connect to where, but this information may be enough once you figure what is connected to where.
I also think that's better to remove the ICs and pull the pins you'll need to rework. This way it's easy to undo the mod and normally results on a cleaner work.
This is what I've done here (some posts ago on this same thread), on a pirate board:
viewtopic.php?f=28&t=14829&start=30#p180384Good luck and nice gaming!!