I've had this machine over a year (bought it broken) and have finally accumulated the skills and time to hopefully get it working. It is Gottlieb's "The Games" system 80A. I have read https://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#System_80_.2F_80A_Power_Supply many times (I don't claim to understand it), and have the instruction manual with all the schematic diagrams too (don't claim to understand these either). Also for these tests the only connection to the power board (A2) is J1. I believe I have replaced most of the recommended parts on the power board (I did that work a long time ago, including transistor at Q3), and have double checked all the work.
The immediate problem: the 5V led is not illuminated and the game does not boot. I've been looking at the schematics and don't understand where the 5V is supposed to be coming from, so I am having trouble figuring out what may be the issue. The 12V led lights up fine, and the 8V at TP5 checks out fine. I get no reading at the 60V and 42V TPs. If I am reading the schematics of transformers output to J1 on the power board correctly, pin 9 is +8V offset (don't know what offset refers to, but since the 8V test point works I assume its all good), pin 7 is 60V AC, pin 8 is 60V AC Return, pin 1 is 12V, pin 2 ground.
So following the schematic from pin 1 on J1 I don't know where the 5V is supposed to be generated. I see it referenced on pin 2 of the IC1 Regulator UA723CN (I tested it with my meter and got about .5v, but all the other pins referenced were outputting what the diagram shows. But since I don't understand the directionality of these things (as in, should that IC1 be outputting 5.1V at pin 2, or receiving 5.1V at pin 2, or if there even is such a thing as direction).
I also see 5.6V mentioned around the transistor at Q3 2N6057. Is this where I should be looking? This is one of the pieces I installed new, and checked for continuity from the legs at R11 and R9 as detailed in the article, and there is no continuity between Q3 and the cold plate.
Also, I read in the pinwiki that (referencing 80/80A) "Unlike the System 1 power supply, the +5 VDC logic power is no longer rectified and filtered on the power supply itself. This process is now handled by a bridge rectifier and a large filtering capacitor located on the transformer panel.", but how can that be true if board A2 at J1 does not have a 5V input, but then the board has 5V at a few places! I do see 5V at connectors J3 and J2, but since the guide says to look for the LEDs illuminated with those unplugged, I thought that board A2 will generate this 5V.
Any help is appreciated! Thank you!
Note: Dont worry about that mess at J3.