Hi Friends,

I have a Stern Magic that has had lots of tampering from the previous owner.

I have re pinned the rectifier board, and changed the 115V factory input setting to 120V

Have replaced the memory cell and repaired numerous fractured solders on the header pins through out the machine. The voltages at the rectifier board check within 15% of spec. I lifted one leg of all the e-caps and tested each - all still healthy and pass ESR.

Game boots and plays, but has major issues with the solenoids being scrambled

For example: Outhole kicker works fine, Left slingshot works fine. Right slingshot switches cause the drop target solenoid to fire. lower left popper switch causes cabinet knocker to fire, Top center popper causes left slingshot to fire.

I manually grounded the collectors of the driver transistors one at a time, to check the wiring to the solenoids. Each solenoid energized correctly when the collector of the corresponding transistor was grounded. So it appears that the problem is at the board.

I noticed that the transistor arrays ( U1, U3, U4 ) are warm to the touch when the game is on. Resistors 9,11,13, 15,-17, 21-29, 30-47 etc..are HOT. Not too hot to touch, but ALMOST.. In my audio repair experience, a HOT IC usually meant either a shorted IC, or one rail voltage being way off. Since I'm still learning pins. I'm unsure what to make of it. I need to get myself a logic proble and some basic board testing jigs.

I'm leaning toward the 3081 transistor arrays being cooked, and or the 74154 IC being junk. Or ???

Any wisdom or advice from others welcome.. Thanks

Thanks - I'll give the self test a try when I can go back to the machine. I will buzz out the leads of the connector between J4 on the driver / reg board back to the MPU

Many thanks - you were 100% correct! I finally had a chance to get back to that machine today, and it only took 10 minutes to find a broken connector inside the housing. I clipped two small pieces of 22 AWG buss wire and clipped these to my meter probes. Inserted these in the housings to buzz out each lead of the cable between the regulator board and the MPU. I discovered one position in one of the housings had no ability to hold the buss wire in place. That was the broken one. I replaced it,and now the machine is fully working! Interestingly, the other connectors don't show any sign of fatigue. There is no evidence of battery leakage or corrosion. It appears this one single contact gave up, for some reason. We all know that they can, and, do crack. Anyway - I really just wanted to thanks again for your help.