Hey Guys! First time here! Looking forward to gaining some knowledge and assistance on my issue.
I have a 1981 Bally Embryon I'm restoring. I've already done a great deal of component replacement and repair. All 6 circuit boards have had 99% of all the individual components replaced with exception to the MPU board. The CPU and memory are original, but the PIA's are both changed.
Here are some videos, attached some pics of some very bad connectors and rusted components on the MPU board i replaced.
The guy who had this machine before me never did a single thing to it except change BR1, everything else was original. it was also in a damp cold environment. Found tons of burnt connectors and melted resistors and rusted caps, you name it.
Basically, the left top bumper and the bottom left bumper occasionally fire AND score when hitting the flippers a lot. First off, this happens even when the switch is blocked with a piece of paper, so the switch on the coils are not too close. Switch test shows no bad switches, all test correctly. So its definitely EMI coming from the flippers I think.
I also just added some 2.2uF 250v non polar caps to the EOS switches as well to get rid of the arcing (the machine did not have them originally for some reason) My thought was too that adding these caps would also minimize the EMI from the flipper's magnetic field collapsing. I've also added some ferrite chokes on the wires at the flipper buttons.
After all this, i still have the problem
Here is a list of what I have already changed or fixed:
-All components on all circuit boards changed except the MPU board, just the U10 and U11 PIA's changed
-All the PF switch diodes and caps
-ALL solenoid coil diodes replaced
-Flipper button leaf switches
-EOS caps for arcing and EMI reduction
-EOS switches on all flippers
-All burnt out lights and cleaned/resoldered any bad sockets
That's what I have so far. I'm starting to pull my hair out and run out of places to check for problems. I still yet to replace all the molex connectors in the machine too. That is on the agenda to fix, however, they all looked still in decent condition. I have diligently checked all the boards for broken solder joints and have fixed them all. I lucked out and the machine did have its battery relocated in a safe position so no alkaline damage on any of the boards.
My first thought is its got to be something on the MPU board, maybe a bad capacitor or diode?
Thanks so much for the help guys, hope we can trace this issue down!
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Post edited by Pinwiz1985 : added video links and photos