Quoted from RGarriott:
Yep. I was wrong. But i do believe the transformer is bad. I took all the dc and ac readings on my firepower board and then went out to the AP to get those readings. They were considerably different from each other.
I wanted to eliminate either the power supply or the transformer so i installed the power supply board in my firepower. All readings were good. Looks like i have a bad transformer. Readings are as follows
F1. 153.6. 88
F2. 10.5. 38.4
F3. 5.3. 17.8
F4. 10.5. 38.4
Ok you've got the right ideas here, just need to tweak a couple things. While comparing voltages between the working and non-working games is an excellent place to start, you need to know exactly what voltages to look for and where to find them. Do you have the schematics for AP? Unfortunately IPDB.org doesn't have a set so I'm using the power supply board schematic from a Blackout instead...i think it should be the same as AP or close enough. That said, here's what we have--i added green arrows to point out 5 fuses:
Starting at the top you can see fuse 1 (F1 on schematic). If you follow to the left of the fuse, it's showing Display 90VAC. The wire leading up to the fuse (3J1-4) and the one below it (3J1-9) are carrying 90VAC from the transformer to the power supply board. In order to check that the transformer is supplying 90VAC to the board, you'll want to set your meter for AC volts and check between 3J1-4 and 3J1-9. If you have 90VAC there and the fuse is good (always check fuses by pulling them out and check with meter), and have verified that you have the correct type/rating of fuse installed--in this case a 1/4 amp slow-blow fuse-- then jot down your reading (AC volts) than move onto the next circuit, at fuse 2/F2.
F2 is a 2.5a slow blow fuse that protects the solenoid circuit. You should get around 28VDC coming in from one of the bridge rectifiers (not shown on this schematic, and unfortunately not included at all with this copy)...That can be tested by setting meter to DC volts, red probe on either side of F2, black probe on ground. Again, make sure you have correct fuse type and rating.
F3 is for the CPU controlled/lamp matrix lamps. 18VDC should be coming into the board from the other bridge rectifier mounted in the backbox, and can be checked at F3 the same way that DC volts can be tested at F2. Verify correct fuse type/rating.
F4 is 28VDC for the flipper coils, tested same as F2+F3. Again, verify proper type of fuse and rating. Note this voltage is also comes from the backbox-mounted bridge rectifier for the coils.
F5 is protecting the 12VDC that gets converted into 5VDC by the voltage regulator on that big heat sink on the power supply board. You should find approx 12VDC at fuse F5.
The transformer is not very likely to be bad, though anything is possible. If any of these voltages are missing or incorrect, you can unplug the transformer from the power supply board (big rectangular 12-pin plug at lower right) and test each of the transformer windings individually. Again, transformer failure is pretty rare. Power supply board issues, however...
Now that I've got that all written down, I'm noticing F2 and F4 on your game are at less than 1/2 the voltage that should be there--i would recommend checking the bridge rectifier that converts the AC from the transformer into the DC voltage the board supplies to the coils. Again, the schematic i am working from doesn't include the rectifier wiring so I'm not sure which rectifier it will be. There's only 2 in there, so it'll be easy to figure out.