Bally Midway pinball solenoids not working

[Shaggy]

I have an '84 Kings of Steel that I've owned for a number of years. About a year ago it started to give me some troubles on start up. The first thing is the beginning "gong" then the pop out fires volume starts, lights etc. Well it began with the gong had a funny sound to it and the pop out wouldn't fire. The ball ramp solenoid wouldn't send the ball up and the flippers wouldn't work. Usually I could shut it off and restart and it would be fine. Then it started doing the flipper thing and pop out during the game. Now I can't get the solenoids to come on at all. I changed out the solenoid driver board with one I bought off E-Bay and it didn't change anything. Is this possibly the MPU? Battery has 3.45v and I've unhooked and cleaned all the connectors on both of those boards. I'm stumped. Do I need to look at getting new boards for one or both of them? Thanks'

Dave

[rokgpsman]

Are power supply voltages ok and with little ripple? As the years go by capacitors in the power supply can dry out and not do their job. Besides filtering the ripple out they act as storage for the amps needed when things like a solenoid get activated, otherwise the voltage line sags (drops to a lower level for a short time). This may not be it but something to check out.

You probably already did a good inspection of the mpu board, no battery leakage or other contaminants on the board?

If there are any chips in sockets you might want to remove and reinsert them. Chips can sometimes work their way loose due to heat and cooling cycles, not making good contact with the socket contacts. Plus socket contacts and chip legs tarnish over the years.

[Shaggy]

Hey Rok, sounds a lot like working on a slot machine. The board is clean (battery) but I need to get it out to take a look at the caps and such. I really like the machine. Yeah that gives me a good start on what to look at. Thanks for the info.

Dave

[rokgpsman]

I forgot to mention to check the connectors. A lot of pinball machines use similar molex connectors to what is used on slot machines and you know what happens on the S+ power supply molex connectors, where they turn brown from overheating. The contact pins often get tarnished and make poor contact. Plus where the male pins are soldered to the board the solder often cracks and makes for an intermittent connection. Repair guys often reflow all the connector pins on a board.

It could be your mpu board that is the problem but is good to eliminate other things that are not too difficult to check.

[Shaggy]

Absolutely and I will check them out thanks.

Dave

[PinJunkie]

Only thing I can think of is the capacitors on the power supply. These usually cause resets when you press one or both flippers but they can also cause other issues. Your description of how the problems gradually got worse can only be explained by something that gradually deteriorates. Those big caps are the first that come to mind. Having said that I've found that removing and reseating the power connector also helps in many cases.

[Shaggy]

Only thing I can think of is the capacitors on the power supply. These usually cause resets when you press one or both flippers but they can also cause other issues. Your description of how the problems gradually got worse can only be explained by something that gradually deteriorates. Those big caps are the first that come to mind. Having said that I've found that removing and reseating the power connector also helps in many cases.

Thanks, as soon as I get time I'll check it out.