Does the fuse blow on a single flipper hit or after you hold the flipper?

How did you test the EOS switch? Go into switch edge test and make sure it's working.

Check solenoid diode and resistance on coil if a single hit blows the fuse.

The same thing happened to my TRON LE back in October 2012.
The problem was not the fuse.

The Q16 MOSFET on the I/O board had shorted.
Once I replaced the MOSFET with a new one, the flipper worked fine.

It has not been a problem since I replaced it. I also have the same mods minus the Flynn Sign.

If you need the MOSFET, just send me a private message with your mailing address, and I will send you one. I bought a couple in case I messed up the board swap with the first one. But luckily, I didn't mess up.

Marcus

Biggest board in the head - you can't miss it.

LTG : )

See Picture:

also the hum "problem" can be searched for on the Forum very likely not related just part of the construction of the newer sterns. Some can get the hum out some just deal with - some can't get the hum out. From posts in the past the Mosfet stern is using are having problems keeping up with flippers these days and often fail premature. In the past Mosfets have been an easy board repair for myself - first one I have done.

Also you can test the Mosfet prior to replacing it but I would say from having seen this in the past its a very likely possibility.

DSCN0146.JPG

To test it, you need a DMM. Put the DMM into "diode" mode and test Q16.

Black lead on metal tab (middle leg). Probe the two outside legs with red lead. You should see between .4v or .6v. If you get a reading outside of that the transistor needs replaced.

http://pinwiki.com/wiki/index.php?title=Bally/Stern#Testing_and_Replacing_Transistors

Afraid you can't accurately test a mosfet with that procedure. They don't work like normal transistors.

Use the following test for mosfet's:

http://www.4qdtec.com/mostest.html

Or better yet, take some voltage readings.

It's more like a transistor than a mosfet.

Patrick of Stern Pinball told me the following:

"I’m suspecting the Q16 transistor on the I/O board has shorted. You can replace the transistor with an NTE2987 transistor.

Regards,
Patrick"

In any event, I believe the problem will be resolved with replacing Q16.

Marcus

That's true but you usually can test if they're outright shorted using the tab of the MOSFET to the ground plane. In this case I predict it's a direct short.

Nevus: a blown transistor can fry your coil and a shorted coil can fry your new transistor also. Make sure you get a dmm impedance read across the lugs of the coil. If those are also directly shorted, replacing your transistor it will just blow again. So test both at this point. Coil being bad is uncommon but not unheard of.

You are correct.