Whirlwind Pinball Repair - Intermittent Fan/Blower

Author: Wayne Eggert
Date: 8/31/2011

Problem Description
Blower fan on a Williams Whilrwind Pinball was working intermittently.  On a Whirlwind, when the 3 spinning discs in the center of the playfield are spinning the fan should also be blowing.  In my case the fan would blow but then stop several times while the disks were still spinning or stop entirely.  Sometimes it would blow the entire time.  Shaking the machine slightly caused the fan to begin blowing again.


Diagnosing
My initial thoughts were that the issue with the fan/blower was being caused by the same issue with the missing/crackling sound that I had addressed.  For that reason, and that reason alone, I had not pulled the triac board from the machine.

It appeared that jiggling the cables in the backbox leading to the triac board or the connectors on the triac board would cause the fan to mess up.  Since I had just fixed the sound issue & still had the same symptoms with the fan/blower I decided to poke around on the triac board.  I found if I pressed against one of the connectors the fan seemed to start/stop.

Here's a Youtube of the issue:
http://www.youtube.com/watch?v=Rg9Htm7W_S0

Problem Resolution
After pulling the triac board, the issue was very clear.  The cement resistor on the board had completely broken free of the board and was essentially hanging loose.

Picture: Back of Triac Board from Williams Whirlwind; Loose Cement Resistor

The picture above shows the back of the triac board where the cement resistor had broken free of its solder joints.  Since this board is mounted under the top of the backbox the resistor would pull down on these solder joints and the fan would work fine.  But as the machine vibrated some from the solenoids, fan motor, etc it would create vibrations and break the connection since the resistor was just hanging in there.  This needs to be resoldered.  Also a good time to inspect the other solder joints and resolder anything else that looks cracked/broken.

Picture: Resoldered Connections on Triac Board

Above is the board after the cement resistor connections were resoldered & also several other pads were resoldered.  All ready to go back in the machine for testing.

Results / Conclusion
After reinstalling the triac board in the machine, the fan has been working great!  So if you're having intermittent fan issues, definitely suspect the triac board.  It still goes to show that having several intermittent issues at the same time can make it more difficult to diagnose the problem, but once you start chipping away at the issues you can start making some real progress.  I *think* my Whirlwind is completely 100% working now.. yay!