Nitro Groundshaker Issues

[SirPeale]

I have a client that has a Nitro Groundshaker.  When I started it was completely non-functional.

I was able to tell after some minor repairs that the MPU board was scrap.  I bought a "Mutha.PCB" from Tom Callahan.  After changing a few fuses, everything lit up.

I have *very* few solenoids.  The coin door lockout coils, the knocker and the relay all fire off during solenoid test.  During game play, nothing fires off at all, although the flippers still work.

On the power board, I get proper voltages on all test points *except* TP4 - I get 0.  If I'm reading the docs correctly, all this does is GI lighting.  Which is odd, because everything is already lit up!

Ideas to get the solenoids working?

[SirPeale]

Bah...I spent an hour on this today, and now I find this:

http://www.twobits.com/images/ballytesterbook/ballytesterbook.html

If only the knocker and coin door coils fire, but none of the playfield coils work, the fuse hidden on the underside of the playfield is blown.

I didn't even know it was there.  A ten second fix.

[modessitt]

Ha!  I was just about to reply to your first post to check the solenoid fuse under the playfield, when I saw your second post.  I'd keep an eye on it as fuses don't usually blow for no reason, although they do get old sometimes and fail for only that reason.  I'd suspect it's more likely that a slingshot or pop bumper switch got stuck for a bit and locked the coil on, blowing the fuse instead of burning out the coil or drive transistor.

[SirPeale]

It's actually age, more than likely.  I've replaced most of the fuses on this unit now.  Near as I can tell, they were all original.

[ChadTower]

When a fuse is burned you can usually tell by looking, sometimes needing a magnifying lens.