With the original SDB installed, F3 on the rectifier board blows at power up. I have an Altek mpu board installed. First it would almost boot completely and give me all 7 flashes, but then the red "over voltage" light would come on and not boot.

Now it won't even get to that point, F3 on the rectifier board just blows immediately.

I don't believe the problem to be on the rectifier board because I put a known working one in the game and same thing, F3 blew immediately.

Edit: Installed a new Altek solenoid driver board and now nothing is happening, only the red light on the mpu comes on that says "over voltage".

Any advice is appreciated!

I just put a new solenoid driver board in and now the red light on the Altek mpu come on that says "over voltage". Nothing else happens. Doesn't boot, no flashes, fuse doesn't blow nothing.

TP6 on this new solenoid driver is low. Should be 5V but measuring 1.6V

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Rectifier board tests:
TP1 7.5
TP2 205
TP3 15.88
TP4 5.6 VAC
TP5 43.6

The original solenoid driver board installed the F3 fuse on the rectifier board blows immediately. With the new Altek solenoid driver, I just get the red light on the mpu, nothing happens.

Reading a few other threads, it seems as though the "over voltage" light on the mpu can also mean under voltage which I assume is the problem here based on the TP on the Altek solenoid driver measuring low. 1.6v when it should be 5v

What should I look at?

Also TP3 on the Altek SDB is low. Should be 3.3v but measuring 0.78v

Just measured it and pin12 on J3 on the SDB is 16.46

Pins 13-16 on J3 on SDB are all measuring around 1.5v

I think they should be 5v? Any idea why I'm not getting 5v there? Thanks!

Thanks, guys. I just made sure all the wires were plugged in well at the mpu as you suggested but no change. Wiggled them around while the game was on too but nothing. I did repin these connectors recently too.

Still wondering why I'm not getting 5V on the SDB. I also measured pin25 on J3 SDB and it also comes in around 1.5v. so I'm not getting 5V anywhere on the SDB. This SDB works great in my other game I pulled it from.

Doesn't the mpu get it's 5v from the SDB? Seems that I need to figure out why there is no 5v on SDB.

I'm stumped. Just checked the schematic to make sure and everything is wired correctly and it is.

How can I check to see what may be dragging it down?

As I was going to test this, I noticed that J4 on the lamp driver was off by one pin . Can't belived I missed this, but after I fixed it, the game works!!!!!

Thank you all so very much!! Put the original SDB back in too and all is good!