Hello All - bit of an odd one, hoping someone can lend a hand.

I have a Phoenix (Williams, 1978) and it recently started having an issue where one of the Drop target reset coils is firing and Locking On as soon as the game is Powered On. The solenoid fuse then blows if I don't turn the game off quickly enough.

The strange thing is that if I quickly power the game off/on/off/on a few times, it will stop locking on, and the game will function normally EXCEPT there's no sound. Coil always locks when game is powered on now.

I have a brand new sound board in there, and everything has been great for a while now, no issues. Here's the only thing I did:

The battery holder was unusable. Pads were broken off, etc. I had been using the power on/off method to boot the game, since I had not replaced the battery with a remote one yet. So today I simply cut off the holder, and added in a remote battery pack per usual. Seems to be doing its job, but the problem started right after I cut off the old holder. So I took the remote battery pack back off just in case something was wrong there, but no change.

Anyone run into this kind of thing? Honestly not sure where to start. What would kill the sound AND lock just one coil on like that out of the blue, but flipping the power switch a few times makes it act normal? Transistor is testing good. I'm mind boggled.

That's normally what I do first, but this has been running rock solid so I let it be for now. It feels like something odd might have happened, which is why I posted since the symptoms are strange.

UPDATE: Today I plugged in the game and turned it on (remote battery still detached, so no battery at all right now as it was for months and working with the on/off trick). The game booted fine, and coil did not lock on. I started a game, and the Sound also worked fine. Only issue is that now the Coil that was locking on is no longer firing at all, so the drops associated don't reset.

Thinking I will replace the associate transistor/driver just to see if that fixes the issue. If not, I guess I'll have to do the 40-pin and go from there. Any other suggestions, please feel free. Still confused why removing a non-working battery section would cause this, so maybe just a coincidence.

Not that I noticed. It's a easy/gentle snip to remove it. Same with installing the remote. I didn't pull the board, since you can just solder to the ends of the snipped piece easily enough.

I just turned it back on, and the coil was locking again. So I removed the transistor TIP120 and put in a spare TIP122 I had around. Issue still there. Going to try the pre driver transistor since I have some 2N4401's around. If that's not it... I guess I move on to the 40-pin. Unless there's something else that might be grounding it and causing it to fire? Wondering where else I could look?

Q23 and Q22 replaced... still locking on.

I assume try the 40-pin next, before worrying about stuff like IC2 (7408) or IC5 (PIA). Going to have to order some connectors/pins, I'm all out of 40-pin.

Anything else I should try while I wait?

Finally received and had time to replace the 40-pin interconnect... sadly, no change.

So I still have the same coil locking on whenever the game is powered on. What's next? the 7408 or the associated PIA? Trying to decide where to go from here. Very frustrating, since this was working great for months.

I'll double-check that and make sure it's okay.

Attaching a pic from the schematic for the solenoid in question.

Phoenix_Sol_Schem1 (resized).jpg

Coil and diode are good. Should I be looking at IC2 7408 next?

Picked up some 7408's... going to try replacing IC2 and see what happens.

Just to verify - removing the battery holder and not installing a replacement would NOT cause this kind of issue right? No battery holder shouldn't affect anything, since the holder itself was empty of batteries before I removed it.

Replaced IC2 7408 ... coil still locking on at power up. I'm stuck.

Update: I also swapped the wiring on the drop target reset coils, just to make sure it wasn't the coil. The other coil locked on, so it's not a coil/diode issue for sure. Removing the connector from the board stops it from locking on, so it has to be a board issue. Not sure where to go next... help please?