I picked up my first system 6 game the other day, Firepower. On power up the game won't boot and the CPU board has the two red leds steady on. GI lights are on. Voltages test good on the power supply board and the CPU has 5v at the test point. None of this really concerns me at this point after having read this entire thread! I've placed an order with GPE and Barakandl for all the bullet proofing components needed per all the previous posts. Thanks Vid and everyone for the efforts put into this.

My question is relating to the bridge rectifiers. On initial inspection I have three of them in the backbox. Seems all of the schematics I've looked at show only two. I'm planning on pulling all the boards in the next few days and want to sort out this situation as well if it is incorrect. Any thoughts welcome!

IMG_3744 (resized).JPG

Stuck my head in there and you are correct, yellow GI wire and two reds going back to the GI fuse block. Good catch on the soldered board wires too. I will get the molex board connector from GPE and fix that too.

I'm in the process of rebuilding my Firepower and have done all of the updates in this thread. A year ago when I got the pin it wouldn't boot, two solid red lights on the MPU. Tear everything down, rebuild the boards with kits from GPE and info from this thread. Today I reinstalled the boards, reconnected everything in the backbox, threw the power switch and two solid red lights on the MPU again. Hmmm. Voltage on the testpoint #9 was +5.05v and testpoint #1 was 12.4v. Looks fine. Time to do some more reading on this topic and educate myself on what to do next.

This is where things get strange. I always start with power when I don't know whats going on. So, turn the power off and unplug all the connectors from the power supply board to check voltages. AC circuit fine, solenoids fine, lamps fine, but the +5v outputs on 3J5 and 3J6 read +12.4V. What? Input leg on fuse F5 reading +12.4v as well. So, I'm not sure exactly whats happening here. I'm guessing a bad 5v regulator but then how did I get 5v at the tp#9 on the MPU a few minutes earlier?

I figure I should replace the 5v regulator on the power supply but I'm having trouble sourcing one or equivalent. Looks like LM323K are hard to find. Any thoughts or suggestions welcome

Thanks, I'll check into that.