Hey All,

I'm new to pinball, I picked up a bally supersonic that didn't work as my first pin.

Turns out the battery on the MPU board had leaked and done some damage. When booting I only got 2 led flashes; there was some corrosion damage to one of the sockets; I ran a jumper wire from two traces to the correct legs of one of the chips and now the machine boots completely. I'll be ordering the Bally Battery corrosion repair kit from GPE as soon as they start taking orders.

Now that the machine boots I ran the diagnostic tests and am having an issue where the saucer and outhole solenoids do not fire. If I jumper the solenoids to ground they fire fine. When I jumper the transistor on the SDB they also fire.

I found a thread on here where somone had a similar problem and got some advice on how to test the SDB further:

https://pinside.com/pinball/forum/topic/1978-bally-outhole-kicker-dead

Grab a jumper wire and connect one end to test point TP6 on the solenoid driver board (SDB).
Very briefly touch the other end of the jumper wire on the banded side of diode CR4 on the SDB. Does the outhole kicker activate?

Next going upstream, remove the jumper wire from TP6 and connect it to the GND test point on the SDB.
Very briefly touch the other end of the jumper wire on pin 8 of U1 on the SDB. Does the outhole kicker activate?

I followed Quench's testing procedure above and the solenoid fired both times. If I understand the thread correctly this leads be to believe the SDB and U1 chip are fine and that for some reason the SDB is not getting the signal to fire the outhole or saucer from the MPU board. In the above thread the issue was one of the 4 solenoid signal wires from the MPU board was not connected correctly. On my machine those 4 wires are all in the correct spots.

I'm guessing maybe one of those 4 wires is not making contact. I tested the header pins for continuity to there respective traces on the SDB and MPU boards and they check out fine so if it is a connection it is in the connectors; I'll be repinning them as soon as I get connectors from GPE.

Is there anything else I can test or that you all might suspect?

Thanks!

Thanks everyone.

Quench , I ran the test again and noticed the drop target is firing when the knocker is supposed to but the drop targets fire again when they are supposed to. What do you think that means?

I removed the boards and checked the traces on j4 pin 1-4 on the mpu board with a meter and they seem fine. The sdb looks good too.

Thanks. I removed the wire from the connector housing on both ends, neither looked corroded and I retensioned them. I also tested the connection on the mpu side by checking for continuity from pin1’s resistor on the mpu board with j4 plugged in and pin3 on the SDB connector, it checked out. Is there any component or connection on the mpu board I could check that could have failed that would cause it to not be able to pull that line low?

No logic probe. I tried to measure resistance between those two pins and got an open loop. I checked the boards separately and was getting 466ohm resistance between pin 13 of u11 and pin 1 of the j4 header but get an open loop on the sdb. Where on the board is pin 20 of U2 supposed to connect to? I couldn’t tell from looking at the board.

I did check that pin3 on J4 was good but don’t know what else to test.

Oops double post

Quench, you are the man! Thank you so much.

I looked at the back of the board more carefully and although the pin was soldered firmly in place there was a small crack as soon as the solder "blob" contacted with the trace. Everything works now. If your ever in the SF bay area I owe you a beer.