Resetting when one coil fires

[Reddogg]

My Roadshow pin is resetting when a particular coil fires, but no fuses are blowing. It even happens in test mode, but sometimes it will fire without resetting the game. It started happening due to something I stupidly did. I was fixing another issue, and re-testing my voltages in the harness that goes to this coil. Using the ground strap to ground I touched a wrong wire in the harness, and the game reset, and now I have this new issue. Good news is I fixed the old one.

After reading, it appears that I should look at my associated bridge rectifier/diode.

Just wanted to double check if I was on the right track here. I don't want to waste time shot-gunning.

Thanks.

 

[viperrwk]

You might have blown the diode on the coil. I'd put on a new one and see if it solves the problem.

viperrwk

 

[Reddogg]

You might have blown the diode on the coil. I'd put on a new one and see if it solves the problem.

viperrwk

Okay. There isn't one on the coil itself, so I'll check the one in line with the corresponding transistor on the power driver pcb.

It's for Q64, so looks like D25 (a 1N4004) is the one to check.

Thanks!

 

[Reddogg]

Well, D25 is testing as good, so guess I'll test the TIP36C and resistors.

 

[Reddogg]

Well, no luck in finding a bad component. I tested all resistors, diodes, transistors, and bridge rectifiers in the high power circuit, and everything tests as good. I'm referencing p.3-8 in the manual. I did test everything in circuit, but out of the cabinet, except for the 1N4004 diode (removed and tested).

It's possible that something tested good, and is really bad.

Any ideas on what the most likely culprit is here?

Again, game resets 99% of time when coil #5 (upper right diverter) fires.

 

[Reddogg]

Replaced the 1N4004 anyway, and now I'm back to my original problem with my replacement dozer blade opto.

https://forums.arcade-museum.com/showthread.php?t=401103

But, I no longer have the zap from the bracket that the opto is attached to, and now it hardly ever blows a fuse (once in like 50 coil #5 firings), and instead will reset the machine.

Has anyone ever used one of these replacement optos on their Roadshow and experienced any kind of issue at all?

 

[Reddogg]

I spent the last three days checking everything I could think of in circuit with the solenoid #5 that is the problem. I am no longer blowing fuses, and I fixed the voltage leaking thru the mounting bracket of the RS-BOB (perhaps why fuse no longer blowing), but for the last several days now, the problem is that the machine resets with the RS-BOB hooked up. I ran new test wires for both power and ground to coil #5 (no change), I tested everything on the power driver board (all resistors, transistors, bridge rectifiers, diodes) and everything tests as good (though something "could" still be bad), I put new connectors going to the power board for ALL coils (power and ground), and I rewired the harness that goes directly to coil #5.


I thought I had it fixed just a little bit ago, after I rewired the harness going directly to coil #5. I ran coil #5 repeatedly in test mode for 13 minutes without a reset! But, then it started resetting again, and now it resets every time coil #5 fires.


I have no more hair left (it's all been pulled out). Either the RS-BOB is bad, or there is something so phantom-like in my machine that I won't find it until another problem begins to appear.

Sending back the RS-BOB.

 

[Reddogg]

Wow! A thread all to myself? All good.

And just when you thought all hope is lost...the solution is found!!!

I can't stand not figuring out a solution to a problem, so I went back to it. And this time, I saw something I never saw before. It turns out, the hole in the power lug of coil #5 itself, where the coil winding attaches to the lug, was shorting out against the stop bracket that holds the coil in place. It wasn't held in place tightly enough, so the coil was shifting when it fired. (Unfortunately, the plastic base of the coil does not have the little tab on it that locks with the stop bracket to prevent movement/shifting of the coil). That movement was causing a short (a spark) between the hole and the stop bracket. This explains the intermittent functionality as well, because sometimes it didn't shift enough to cause a problem, and other times it did. And even the raising and lowering of the playfield was causing the coil to sometimes shift enough to where the short would happen or not happen.

I solved it by wrapping the stop bracket in electrical tape, which also created a more snugging fit, so that the coil now can't shift enough to make contact and short out again.

Going on 30 mins of repeated coil #5 testing without any issues.

It looks like the problem HAS been finally solved. I haven't seen/read about anyone ever having this problem before, and I've been researching for days. My apologies for all of the posts, but I'm one who talks out loud while I think. And I'm glad I found this problem before it could have caused another issue somehow!

Perhaps someone will read this later and find it useful (or not) during their own troubleshooting.

As for the RS-BOB, great product! It can even help you find an issue in your cabinet that you might not know about.

Order one here if you need one:

http://www.greatlakesmodular.com/