Hi everyone

I am having issues bringing a Whirlwind back from the dead after years in storage. It now has a new Rottendog MPU in it and is booting up and playing normally. However, the upper right flipper does not work.

Initially I noticed the bottom flippers were weak. Only the hold winding of the coils were working. This was due to corrosion on the EOS switches which meant they were always open. I replaced the EOS switches and then the bottom flippers started working normally. I was expecting the same issue on the upper flipper but it doesn't seem to be it. I used a clip to short the EOS switch and the flipper still does not work. No action at all. I have 75v at each of the coil lugs. I thought the issue was the coil, but I replaced the coil and diodes and still have the same problem. Fuses are OK. When I ground the non-banded side of the coil with a jumper wire, the coil does activate, but only very weakly. It's not even strong enough to fully pull the plunger in. The flipper plunger and crank move freely by hand so it is not a binding issue.

I have absolutely no idea where to go from here. Grounding the coil manually should always produce a full force flip, yet I only get a very weak one, and not even a full flip at that. However the coil was replaced and there was no change in behaviour. I verified wiring was correct on the coil lugs.

Where should I go from here?

Hmm - good question. No, I think I removed the jumper wire by that point.

Bump! Anyone else have any suggestions?

Interesting. I admit I did not test the middle lug, just the non-banded lug (lug 1). I grounded lug 1 on the other flipper coils and they fired at full strength. However I had replaced the EOS switches on those flippers so the EOS was working. Next time I am in front of the machine I will do this test. I assume that grounding the middle lug should fire the coil at full strength, therefore proving the EOS is the issue. Probably the same thing zaza was hinting at in his post.

In any case it sounds like the EOS is the main culprit so maybe I will just replace that and see how it goes.

Of course. If it's not the EOS and I verify wiring is good to the boards, what else can I do to check power? I already have 70 v at each of the coil lugs.

Just an update on this. The issue turned out to be a couple of things. The coil worked fine when grounding the centre lug. The EOS switch was corroded and not making reliable contact. However the connector to the driver board which supplies the flipper power was also loose in the housing. After fixing those two things, the flipper started working again.

Thanks for the help, everyone.