I have a Gottlieb System 80 (Volcano) that originally had a weird booting problem. When powering up, both the ball feed and ball kicker solenoids would be/stay energized with a zero on the credit display. If left in this condition, those two solenoids could burn up or blow their fuse.

After a lot of messing with control boards, connectors, power supply, etc., it started booting fine and for a couple weeks, never one boot up failure. I was so confident in my repairs, that I was able to remove/reinstall the motherboard, or any other control board at any time, and it would boot back up without any problems.

Now comes yesterday, without touching anything in the head of the machine, I lifted up the playfield to install new drop flags, replace some bulbs, replace the ball kicker solenoid, replace a drop bumper, etc.

However, it seems that the simple act of lifting the playfield has caused this annoying boot-up problem to return. This makes no sense to me, especially when most of the critical connectors are located in the head. Is there anything in the playfield area that could cause this?

Thank-you!

EDIT (8/5/2021): It was battery damage in the MPU reset section all along. Several resistors were broken in places you cannot see. Lifting the playfield might cause the harness to pull on the boards. Any temperature changes or physical movements might have caused a resistor to temporarily open up. Performed the MPU reset modification and problem finally solved.

There is a crater/divot at the top, the ball goes in and then this solenoid kicks it out. This solenoid was burned out weeks ago as a result of this original boot problem.

And the top pop bumper, but that was only removed to replace the plastic shell.

I know, I know... but that's my whole point, I even did the ground modification a few days ago, one board at a time, and never once did I have any issues with booting. For the last several weeks, I had boards in and out multiple times and it always booted fine. Changed Power Supply parts, no problems. Replaced the battery with a capacitor, changed resistors and chips on the motherboard, etc... again, no problems booting. Now all of a sudden, simply lifting the PF causes the boot problem to come back!

Is there nothing in the playfield area that also causes these boot problems? Is there any particular connector(s) I could remove that will help me isolate the issue to one area?

I'm not doing that slam switch mod as mine seems to be fine. As a test, I created the slam switch boot issue just to see what it did... I don't yet have that problem.

Originally, when machine was obtained....

1. Turn on switch.
2. Clunk... ball release and ball kicker solenoids engage and stay engaged. Both on same fused circuit.
3. Simultaneous to #2 above, credit display shows "0" and score displays remain dark/blank.
4. Nothing changes and it would stay like this until fuse blows or solenoids smoke.

After I messed with head and tinned all board connection fingers, it boots normally...

1. Turn on switch.
2. Sometimes hear the ball release click really quick without releasing a ball.
3. Playfield lights up but score displays remain dark/blank.
4. 5 seconds later, click... score displays show 0's and credit display shows # of credits.
5. Ready for play.

Stays totally stable for weeks while doing all kinds of work removing and reinstalling ALL boards, changing components, adding ground leads, etc.

Lift up playfield to change pop bumper plastic, lamps, drop targets, replace ball kicker solenoid, etc... original problem as described above has returned.

I realize I may need to eventually change every single stinkin' connection, but until then (time & $$), I'm hoping to just isolate the one in particular.

One of the four pop bumpers stopped working yesterday. Unplugged its driver board and plugged it back and it's been fine... I think...

I'm not understanding how the four pop bumper drivers could cause a boot up issue. I can unplug them to verify this.

Yes, I did some power supply work and all test voltages were good; I also previously adjusted to exactly 5 volts. I will verify these again.

Yes... the original boot issue returned in full.

I just re-tinned the fingers on the driver board. I also found two wired connectors that came out of their housing. One was a ground, but since the hard wired ground is installed, that shouldn't be an issue. Anyway, it booted up fine after I did this but the problem came right back on the next one.

I'm now convinced it's one of those damned connectors in the head but which one.

I found it. The 5 VDC connection (CPU side) between the power supply and the motherboard was the problem.

It's booting up every single time again.

Lifting the playfield was just a coincidence and you were correct all along.

EDIT (8/5/2021): I know it's 8+ years later but the above conclusion about the root cause is completely false. After walking away from the game for these last years, I the same boot problem was happening again. I repaired all of the PS connections, and have a new 5 volt indicator LED on the MPU. Loss of 5 volts to the MPU was absolutely not the cause of this issue. It all goes back to battery damage. I did the MPU reset modification and discovered several components, mostly resistors, that were physically hanging by a thread that fell apart on removal. The reset circuit works flawlessly now and no more booting issues.

Did you add the extra wires on the jumper harness too between the cpu and driver board?

Somebody already added these in the past. EDIT: Again, I was wrong. This connector does not have the doubled up power and ground wires, however I will be rebuilding and adding these soon.

Also, re-tinning is good but you have to be careful and there are many in the board repair industry who don't really agree with this practice.

I'm an electrical engineer and I'm not too fond of this practice either, but considering that this is not a programmable logic controller in charge of factory automation, not a huge deal. Besides, the way I've seen the hard wired grounds attached to these boards in some online tutorials is also not that great. If I were charging somebody money to restore this game, I would also not consider tinning the fingers as an acceptable long term solution. The connectors themselves need to be restored eventually.

Anyway, thank-you very much for your help. It was your suggestion to re-check the 5 Volt supply that led me to the solution.

I'm talking about re-pinning the plastic connectors.

There's nothing you could do for the card other than heating and wiping off excess solder.