San Jose, CA
I've been working on interfacing an Arduino with the switch matrix on WPC games and have been studying various diagrams and schematics. What's interesting is that there seems to have been a persistent error on the diagrams in the manual. Let's look at the manual for Getaway:
getaway manual.png
What we're interested in is the line connecting from +5V between D and E on the manual. It shows a pull-up resistor connected to that line, but why is the 5v running there directly as well? It doesn't make sense. TAF has the same picture:
addams manual.png
And in the TZ manual, they redrew the picture, but the line remains:
tz manual.png
For WPC-95 games, the line is gone:
mb manual.png
I've seen various other sites and drawing that copy this line. Why is it in the picture? It doesn't make sense. So then I looked that the full board schematic for Getaway:
getaway schematic.png
In the drawing, the lines cross, but there's no junction point. My best guess is that whoever transcribed this to the manual screwed it up. But why did no one notice and why wasn't it corrected?
I tested an actual TZ board with a DMM and sure enough, that line isn't there.
Has anyone else wondered about this before?
Thanks for your kind words Rob, and of course Chris H. for publishing it on PinWiki
