Black Jack
Bally, 1978Long story short, these flippers are causing me a serious headache. I replaced the rectifier board, solenoid driver, and got a sweet weebly mpu for a black jack I picked up. I put new diodes on the way I found them, but they are acting up still.
372D99FA-A018-4E5D-902B-5FA5C9E2C7A3 (resized).pngC13A2928-BE14-4145-A2C5-2EAE28081BCC (resized).jpegDC0642E9-291B-448A-B2AB-EADD4E3685D8 (resized).jpegIt's normally faulty diodes on the coil that does this because they don't clamp back EMF from going into the system when you release the flipper button.
Are you sure the diode leads are soldered properly on the coil? It doesn't look like they're attached properly here. The diode lead soldering doesn't look like it's molten onto the existing lug solder.
I have tried other coils with diodes and replacing diodes on the original coils the other night, I still get the same result. The diodes were all new. I put in an original driver board and that didnt change anything either. I have never had problems with replacing diodes before or coils. I am at a dead end with this. I will try to clean up all the coil lugs and put another pair of diodes on it, I dont think that is the problem though. Why would both give me the same problem.
What's the history on this game?
i.e. when you bought it was it working? if not what was it doing?
What was wrong with the boards that were replaced?
Have you confirmed zero ohm continuity from the ground prong on the line cord to the ground plane on the rectifier board and the ground test points on the solenoid driver board plus MPU board?
Can you post some clear pictures of the rectifier board?
Machine was bought not working, acid damage to the mpu. Original solenoid and light boards are in and function fine. I bought a rectifier board and connector kit because the original connectors were corroded. I got the rectifier because I thought it would have been an easy fix. I don’t know anything about its past though really. It has always done the same odd thing with the flippers, weather it had the original boards or new rottendog one. I tried all combinations, I have an original bally mpu I might try just to see. I noticed the varistor is missing above the line filter last night.
Quoted from RMarnold:what is it that you are looking for on it?
Looking for clues like wrongly wired connectors, suspect solder joints etc.
Did you check on the grounds I mentioned?
Nothing obvious on the rectifier board though you should clean the solder splash on E12
What's happened with the ground continuity tests?
If you remove the J2 playfield switch harness from the MPU board does the problem still occur?
BTW, you've removed the description of your problem from the first post. Anyone new reading this thread will have no idea what your flipper headaches are 
Quoted from RMarnold:If I did the continuity test correctly I may have a problem. It never read 0.
What readings did you get?
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Monson, MA