So I have someone on the way to buy my Metallica and of course an issue just popped up. Trough switch 4 (switch #18) stopped working a few nights ago so I ordered a new switch and diode since I didn't have any spares. I've had trough switches fail before, so no big deal.

Parts order won't be here until later today so I took a trough switch out of Mustang. Doesn't work. I looked up the switch matrix and all the switches in the row work, but I found the left ramp exit switch also does not and they are in the same column 02. I see the columns are controlled by ICs and not transistors. I have continuity on the switches in the column.

This column is IC-U22B. How do I go about testing that?

Yes it does look good and it ohms out back to the pin. Thanks.

That thought crossed my mind and I'm going to do that now. Thanks for reminding me.

Boards are swapped and updating the code now on the Mustang board that's now in Metallica. Will report back.

Updating the code again - didn't realize the memory chip in Mustang is 64meg and Metallica is 128meg. Just swapped the chips and updating again. Wish these updates were a lot faster.

Now that I have the board at, I'll need to try this. Have to find where the U22B is first.

WTF? I keep getting Error Code 1 when when the update is erasing the flash memory.

Well, the Mustang and Metallica boards are NOT compatible. Called Stern to ask about the Error Code 1 and that's what I was told. Metallica will work in Mustang fine apparently though so it's backwards compatible, but Mustang will not work in Metallica.

Yes, that's what I did, but I also expected Metallica to work with the new board so it was fully working for sale. Then I'd repair the other board for Mustang and just keep my game needing repair. It does appear to be the U22. Thanks for the responses.