White Water
Williams, 1993I have a strange switch matrix issue with the MPU that came out if my WH20. I have a loaner in there for the time being, but I'd really like to get this one working so I can give the other one back.
Basically, all playfield switches don't work. Test report comes up with "GND row short" for a bunch of different row #s.
Following the guides I've replaced U20 (ULN2803) and U14 (74LS374). Where do I go from here?
You should be connecting a logic probe and tracking down the errant signals. Do a little more investigating.
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Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info
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