Just wanted to share this experience as it might help anyone in my shoes:

While cleaning the upper-level drop-target bank on my Haunted House machine, I accidentally reversed the wiring on the drop-target bank's solenoid.

I re-installed everything, turned the power on and -- Thhhppt!!! Poof! -- blown fuse. Game no work...

After locating the problem I realized I made a terrific mistake. The reversed wiring resulted in frying the diode on the solenoid and destroying the corresponding FET on the Ni-Wumpf driver board responsible for that solenoid.

The replacement transistors used in the driver board, 12N10L, were readily available via the usual joints (Jameco, Mouser, Digi-Key) for about 59 cents each. Awesome.

A few days later, a package arrived and I got ready to fix stuff.

This was my first time trying to fix a PCB and I was pretty nervous. I was replacing a 59-cent thing on a $120 board and was terrified.

Well, it was surprisingly easy. I removed the FET from the circuit board and placed the new 12N10L in its place. Note, the Ni-Wumpf circuit boards are double-sided so the solder has to flow from one side of the board to the other. I made sure there was solder on both sides.

I finished soldering, confirmed the work by buzzing out the joints, plugged that fucker back into Haunted House, and turned the power on....

Click!

Everything worked perfectly. Yay me.

(I also have a Ni-Wumpf CPU which takes ten seconds to boot instead of the usual five or seven seconds. This was the longest ten seconds of my life.)

I remember reading that the folks at Ni-Wumpf designed their driver boards in a way that makes it easy to replace the components that are more likely to fail -- the reliable components are surface-mounted while the components that may fail easier are surface-mounted -- and this is exactly what happened in my situation.

A component that was more prone to failure and replacement did indeed fail and I was able to replace it instead of sending the PCB back to Ni-Wumpf headquarters and have them fix it for me.

What this all boils down to is, I'm happy, very happy, with the Ni-Wumpf driver board. It's designed so the solder-savy user can fix common errors. I didn't even need to email Ni-Wumpf to ask questions about what I need to replace.

So, yeah. I fixed something pretty damn important for the first time and it was easier than I thought.

Thumbs up for Ni-Wumpf and their user-friendly "We know what you're gonna mess up" build quality and decisions.

-Bob