Hi there,
1968 Williams machine blowing fuses 15a on the 24V side.
I just need some tips for systematically finding the culprit.

I have isolated the problem to one set of cables (one plug)
there is no obvious problem, burned coil etc.

I was just hoping that anybody who knows any tips or resources would share them.

I have my DMM ready and waiting.
thanks

I just further isolated the problem to one of the wires on the plug (aligator clips and turning machine on and off) interestingly it is not the same color on both sides of the plug, but it is the correct wire... And was working before. Seems to be solid white, now have to sniff it out some more.

Update...
Well, I didn't isolate the problem. The machine is acting sporadically. It restarted several times with one of the (jones?) plugs from the backbox unplugged. Then it started blowing fuses, but never getting to the restart, whenever I press the start button, poof goes the fuse.

It does not blow fuses with two of three plugged in on the backbox, but with that third plugged in it blows.

Any ideas?

Thanks Bert...
in locating the Common.. my schematics are showing 2 colors on the 24v side, black/red and yellow. It seems like black is the one on all of the score reel coils, so I will start with that. It feels better to have a focus point in the troubleshooting. I have done a manual check on the score reel coils and they all do move at least. (I actually had them all apart and thoroughly cleaned.)

Moving ahead.
thanks again.

Will check that tomorrow, going to get a DMM workout afterall!

ok wow. I ran a quick-ish check and there is a LOT of beeping going on. I assume that any black or red wires are commons (since it shows black and red as common on the schematics) and I further assume that any combination of black and / or red are also common. That leaves me with a few non black or red wires to track down. I also am running on the assumption that any wires coming off the score coils qualify as ok also when they beep.

so... any more recommendations here.

All of the score reel coils are functioning to my knowledge. They all move. (none were locked on, maybe dirty to the point of not moving smoothly--but that is fixed) I have only checked them for continuity... will be doing resistance checks soon.

Duh, I do remember writing that. I didn't think it was the coil because it is moving freely (and easily by hand), am I mistaken?

Also, do you know what the resistance should be or where to find that info.

Thanks a bunch.

OK,
checked ALL of the coils and relays, none of them are shorted out completely, but a couple are reading low, like 2 ohms... score reels are all 6+ ohms.

one more note...
In a random continuity check, I discovered that at the fuse junction, the 6v "inserts" and the 24v "line" 15a leads are somehow connected... is this odd?
fuses2.jpg

That's what I was thinking... thanks

Working on the circuit breaker already! Thanks... sounds like 'seek and you shall find' approach might be the winner here. Although I have been seeking more than I want to already. Tenacity sounds like the name of the game.

ok, I have made an award winning video and posted it on YouTube here

This may shed some light on the subject. It may not. but I would love any words you may have..

CFH,
will do all that tomorrow, and report back.
sorry about the video... but glad you found it..,
thanks a bunch.

sorry about that, video link works now...

I do have a schematic of the game, not PDFd but I can create one and post, or however is the best way of putting that one on.

OK!!! I got the machine to reset and stand by for a game (pf not on yet).... I moved the credit wheel oh 5 or 6 credits down and she fired up. I switched it off, now nothing. Lights on the BG, but no reset.

(no blowing of the fuses either...)

any ideas?

ok again...
I moved the start motor by hand a touch and it fired up again, resetting and back to what appears to be normal... but will only credit for 2 players... that sounds like another issue for another post. Still dont know what was throwing that fuse though...

Hey there Pinball Wizzards! I believe that I found the culprit, its kinda weird. On the replay unit there was a second limiting post that was killing the machine. (see photo) When I was getting the machine ready to run, I had spun the wheel past that point, I think putting some weird pressure on that switch. Extra post is off, and machine is resetting consistently with no fuse blowing. On with the Playfield!

Thanks to everybody. Will likely see you soon on one of my other 3 Williams EMs, and who knows, maybe one day I will become a real Pinball Wizzard myself!

replayreel.jpeg

Oh, I forgot. I can get you a PDF of those schematics easy peasy.