Scratching my head... I've got a Stern Stars that I bought with some issues. Battery corrosion was extensive enough to warrant a new All-Tek mpu board. Was hoping that would solve my problems! Obviously, not so lucky. Chime fuse (next to the chimes, below the playfield) was blowing when purchased. Chime solenoid was charred, so replaced that. On power-up the solenoid is now staying energized (not very surprising). I tested all driver transistors on the solenoid board, including diodes, and resistors. All looked good. I tested diodes installed. Didn't want to go on a wild goose chase and have to do a bunch of soldering. I tested the pre-driver transistor chip(?) and it looked good, I think. I've read about the caps needing replacement. i've been reading the techniek/fllipperwinkel write up, which is super awesome btw. I measured AC output voltage at Capacitor 23 and am getting 32V! Supposed to be .3 Vac. Could these issues be related? Still can't start a game. All-tek led flashes show no errors. I probably shouldn't send anymore bad power to the mpu board. Haven't even started looking at why the trough kicker wires are cut.

Nothing from that era. I wouldn't think it's the chip, since the All-Tek board comes with a new one, and it was doing this with the old mpu also.

Thanks for both of your help! I did the powered on test, and Q6 is getting 1 volt continuously. CA3081 is the pre-driver IC. What is 74L154? BTW, I noticed another cap I previously tested was also showing twice the DC voltage on the AC setting. Cheap multimeter?

It looks like CA3081 is just the part number for 74L154. Got it... Thanks again!

Looking in the manual (pg.25) it shows U2 with 74L154 printed under it. However, at the bottom of the page it says "U1, U2, U3= CA3081" Doesn't that mean they are one and the same? Confusing. Sorry, I don't know how to screen shot.

Stern_1978_Stars_Manual.pdf

You guys are awesome.