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.
--
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
Wanna join the discussion? Please sign in to reply to this topic.
Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
This page was printed from https://pinside.com/pinball/forum/topic/wpc-mpu-issue-with-switch-matrix?hl=onlydjz and we tried optimising it for printing. Some page elements may have been deliberately hidden.
Scan the QR code on the left to jump to the URL this document was printed from.
Guelph, ON
Berlin
Chesterfield, MO
Budapest