Laser Cue
Williams, 1984My Laser Cue is blowing the Solenoid fuse on power up. This is being caused by the Power Driver board, just not sure which part. I swapped in a known working Power Driver and the game booted and played fine without blowing the fuse. I swapped back in the original board and the fuse blew again. What should I check on the Power Driver? Thanks!
Quoted from Cheddar:Has the interconnect been replaced on the bad driver board? The reset signal goes to the driver board to prevent the coils from firing at power on. Interconnect problems can cause them to lock on and blow the fuse.
Yeah, the previous owner replaced the interconnect and it looks good.
Does a visual inspection of the board show any burned or otherwise damaged components. You really only need to look at the left side of the board for solenoids. Is one coil locking on or multiple? You may have to sacrifice another fuse to be sure. If you can get your hand on a breaker of slightly lower amperage for can clip it to the fuse clips and save fuses.
Remove the connectors for the coils.
2J12 (special solenoids), 2J11 (sol. 1-8), 2J9 (sol. 9-16)
Switch the game on and see if the fuse still blows.
If all is well, reconnect the connectors one by one with power on.
Prepare yourself for a spark and activation of a solenoid.
If nothing occurs, you may have a blanking problem at power on of the machine.
Peter
Quoted from Inkochnito:Remove the connectors for the coils.
2J12 (special solenoids), 2J11 (sol. 1-8), 2J9 (sol. 9-16)
Switch the game on and see if the fuse still blows.
If all is well, reconnect the connectors one by one with power on.
Prepare yourself for a spark and activation of a solenoid.
If nothing occurs, you may have a blanking problem at power on of the machine.
Peter
Thanks, Peter.
OK I tried your suggestion. When I unplugged 2J12, 2J11, and 2J9 the fuse did not blow.
With only 2J11 unplugged the fuse did not blow. With only 2J11 plugged in (2J12 and 2J9 unplugged), the fuse blew. So the problem seems to be at 2J11.
Edit again: not fixed. Peter pointed me in the right direction. That connector controls solenoids 1-8. So I checked the Transistors associated with those solenoids and found Q15 to be faulty. Replaced the transistor but the game is still blowing the fuse and the transistor every time I turn the game on.
Well I thought I had solved this, but the issue started back immediately.
I replaced the transistor (Q15 for the outhole) but it went bad immediately and the fuse is still blowing at power up. I replaced the transistor again, but again the fuse blew and when i turned the game off and touched the transistor it was hot as hell and testing bad again. So not only is the fuse blowing at power up, but the transistor is blowing too. The coil at one point started smoking and now the cover is toast. I tested the diode (took it off and tested) on the coil and it tests good. replaced it anyway but not sure what to look at next...?
OK, just put the known working Power Driver back in and the fuse did not blow, but the transistor did. The game plays fine except the Outhole kicker does not work even with the known working board.
Put the original board back in and again it blew the fuse, transistor, and the Outhole solenoid became extremely hot.
Quoted from Inkochnito:Replace the coil and the transistor.
Think it could be the coil itself?
Edit: Yes it was the coil itself. Replaced and everything is good.
Yes, a blown transistor can happen out of the blue.
But if the fuse takes a long time to blow the coil may be fried.
Especialy if it has gotten hot and smoking.
Heat will melt the isolation off the wires, creating one big short, blowing the transistor every time.
Do yourself a favor and make a light bulb rig to replace the fuse while you're troubleshooting. It will save you a lot of grief in blown fuses and damaged parts.
Light bulb rig = standard porcelain light bulb socket base, 100W bulb, wires with alligator clips. Remove the solenoid fuse and connect this to the fuse socket.
If there's a short, the light bulb will glow, and things will not blow up. 
Richard
Wanna join the discussion? Please sign in to reply to this topic.
Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
This page was printed from https://pinside.com/pinball/forum/topic/williams-system-7-solenoid-fuse-is-blowing-on-power-up and we tried optimising it for printing. Some page elements may have been deliberately hidden.
Scan the QR code on the left to jump to the URL this document was printed from.
Chattanooga, TN
Piershil