While you are waiting for your caps, you can do a little visual inspection. Remove the boards and look at the back of the connectors. You are looking for cracks in the solder around the header pins. (It is easier with a magnifying glass, but most of the time you can see it with your eyes.)

If you see issues like this, it is best to "reflow" the solder. Taking a soldering iron heat the solder and pin enough to get the solder liquid, then add a little new lead solder. Make sure you don't heat it too much because you might loosen the pins. (There are many who suggest removing the old solder and then adding new, but that is really a pain, and I've had very good luck with just adding new solder. Remember to use lead solder because it is the same type as this machine.)

While this may not be the immediate problem, cold solder joints have accounted for more flaky issues than I can count. When we fixed up our FP2, we played it for 3 months without any problems, then it slowly started degrading. After reflowing the solder, the machine has been 100% for the last year.

I would also suggest reflowing the driver board and the sound card. (The driver board is probably the most important card to reflow in my opinion.) I assume that you also reflowed the interconnect between the CPU and the driver card.

Measuring caps...go through each of the test voltages and make sure that there is not too much ripple (AC voltage on the lines). You should have less than 100mV of AC voltage. Basically you measure between the test point and ground. (Red lead on the test point, black lead on ground). Measure both AC voltage and DC voltage. DC voltage should be about the right value as on the schematic, while AC voltage should be < 100mV. If it is more than this, you need to replace a cap or two. On the schematic it will list the cap value and the voltage. Buy through either Mouser or Digikey.

I actually don't get that worried until the ripple goes over 1V. Also, as soon as it gets that high, I pull out a 'scope and look at the signal itself. It's easier in that case to detect other problems if you can actually see the signal. All of the voltages on my FP2 are well below the 1V threshold. Some are close to the 100mV, but most are well below that. It really depends on how the machine was used at that point.

Replacing a cap is really my last resort because I fear hurting the board. I know a lot of other people switch caps just as a matter of course, but I'm always scared I'm going to lift a pad.

Wayout is correct in his statements. The voltages I was originally talking about was with a new caps. Sorry for any confusion.

They are "together" but there is a huge connector that attaches the two boards. (It is the dreaded 40 pin interconnect). If you haven't reseated those two boards, that would be my first step. Those connections are also some of the most likely to have cracks in the solder joints because of the huge amount of force required to take apart/put together.

Doh! My bad. I saw the FP2 mentioned and swapping power supplies, and I just assumed it was the same system. My apologies. Should have looked it up.

I wasn't meaning to the processor, I was meaning to the solenoids, motors, etc. Yeah, if there is that much ripple on the regulated supply to the CPU, I would be worried. Power to a CPU is usually going through a voltage regulator instead of just a bulk cap to clean up the ripple. That is a completely different type of circuit.

It comes down to what is being measured and how it is used. I may have incorrectly assumed that we were talking about voltages to high power things, not power to things like the CPU.

If you have a multimeter you can measure each voltage. On my power supply boards, there is a test point for almost every voltage. Put the black lead of the meter on ground, and the red lead of the meter on the voltage test point and read each of the voltages. Measure both AC voltage and DC voltage. Write the numbers down, and either look up the capacitors on your schematic, or post answers here and we can help you look them up. If it is a bad cap, the AC voltage will be high.

I tend to buy caps from mouser or digikey. They tend to be a lot cheaper. If you have other pinball parts that you are ordering at the same time, then I go with the pinball parts supplier.