Excuse me if this is a dumb question. I have a game where a couple coils won't fire. I took out all the fuses and they checked ok. I started checking controlling transistors and they seem okay as well. I looked at the coils that aren't firing and they don't seem to have a broken wires. I checked the resistance on the coils and they are 4 ohms. I next checked the power to the coils. They both have power (the outhole has 30V--I am concentrating on this one right now). I next turn on the game and short the ground lug to the ground braid on the inside of the cabinet and the coil will not fire. I also tried going into the diagnostics menu and doing the same thing...nothing. The coils don't work in game or through diagnostics test.

The game is DE TMNT.

Questions:
1. Can a coil ohm out "OK", have power, and still not work?
2. What the heck else should I do?

Thank you!

Thanks for your reply Chris.

yes I have power at both coil lugs on the same coil.

I didn't think about that. I will try it tonight when I get out of work. Thanks! Seems weird but I can short the ground lug on the slingshots to the braid inside the cabinet and they work fine...although they aren't on the same circuit.

Another weird thing, the manhole VUK coil which is powered by the same line as the outhole and trough works just fine in game and in diagnostics test.

Thanks. I'll reflow the solder tonight. If that doesn't work...I'm stumped Oh, another question...when grounding the ground lug on the coil, should I be disconnecting the corresponding connector to the transistor on the CPU? Seems like a long shot but maybe something goofy on the CPU is preventing me from pulling it down all the way?

Could be a problem too. I thought the outhole for tmnt was 32v. I'm getting around 30.

So now it's acting really funny. Didn't do anything else. I get a really varying voltage from 11-20 volts. Twice it "stabilized" to 34 but before I could test the coil it would drop. Reflow all solder on common power?

Anybody have any suggestions? Seems like the voltage on the ppb varies a lot....so it seems the coils are.

I think the voltage on that particular coil should be 32v. Goes to j6 pin3 on ppb. Yeah def have a problem somewhere. Trying to find where on the ps that voltage comes from. Cn3 pin 5?

Ok that was it. Wire was loose in connector. Thanks for all the replies everybody.

Now does anybody know if its common for f5 to blow on the ppb? It's the 50 volt line for the flippers.

Thanks for the reply. This is a new rottendog board. You think one of the diodes dr1-4 is bad? I would have guessed I damaged one from a problem on a coil....however I don't know much about this board

Will do thanks Chris.

Anybody have a rottendog PPB? Looking at their site, a picture of the board shows the diodes that replace the bridge rectifier are band oriented the same. Wonder if there are different revs or is mine an error? Here is a picture of mine:

diode.JPG

ok yep. That diode is reversed. That should fix my problem. Thanks all for the help.

I found a picture and ended up calling Jim at rottendog to confirm. Thanks for the help. Works great now