Pontiac, MI
Quoted from vid1900:Replace any blackened fuse clips. No, you can't clean them. Once they get hot and corroded enough to turn black, they lose their tension. Use HIGH CURRENT clips here, Great Plains Part Number: 1A1907-03.
Now it's time to test your work.
Rather than blowing up the rest of your boards, it's best to test outside of the game, on the bench.
Connector J2, pins #6&7 take the line voltage (115VAC here in the USA).
Using an old power cord, crimp together a connector you can use for all your Classic Bally servicing.
There are two sources of high voltage, the line voltage (115VAC) and the display voltage (190VDC) - so you need to be careful as you work. Remember that the transformer is ready to shock the careless tech too.
TP1 - (4.6 - 6.4VDC) this is protected by the F1 fuse, and is Bridge Rectifier #1. This supplies voltage to the switched lamps.
TP2 - (160-250VDC) This is protected by fuse F2, and is the group of diodes CR1-4. This supplies the voltage to the displays.
TP3 - (11-16VDC) Fuse F3, Bridge Rectifier #2. This latter becomes the 5VDC that powers the game's logic circuits on the Solenoid Driver Board.
TP4 - (6.3 to 8VAC) Fuse F5. This is the GI lighting circuit.
TP5 - (40-49VDC ) Fuse F4, Bridge Rectifier #3. This powers all the coils in the game.
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Q: Vid, I don't like the big range of possible voltages. Why are they not just nice even numbers like 6v or 12v?
A: Remember these are Unregulated Voltages. No capacitors or voltage regulators have touched the voltages yet. So depending on your home's line voltage, there can be some big swings in the actual numbers.
Hi @vid1900, thanks for this tutorial! I rebuilt my Bally Harlem GlobeTrotters rectifier board and implemented all the bullet-proofing ideas you suggested. One question: why does the 230VDC read low? I power my transformer / rectifier unit on my bench and all the voltages checked ok except TP2 which reads between 150-170VDC. I am getting the correct AC voltage into and out of the transformer block (120VAC in and 173VAC out). I noticed the resistor R3 is an 80kohm whereas the schematic calls for a 100kohm. I would think a bigger resistor would cause a lower voltage out so this would not be the issue. Is there something in this circuit that could be pulling the 230 dc voltage down? I am concerned that one of the didoes might have been exposed to high heat while installing it and testing powering it on... 
