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Title: 5000 Plus Keypad Schematic Post by: dchapma1 on September 08, 2011, 11:00:45 PM All, I plan on building one of these keypads this weekend. I have pieced together the diagram from several posts on this site and thought I would create a readable schematic.
This should be very easy to construct. From what I can tell by a photo of this diagram from a Bally book, pins 1 and 6 are tied together - this is probably how the MPU knows a keypad is attached. Title: Re: 5000 Plus Keypad Schematic Post by: dchapma1 on September 08, 2011, 11:59:15 PM the more I look at this the more I think I am missing something. Simply connecting a row and column together with a switch doesn't make sense. There are 10k pull up resistors on all the lines on the MPU board holding the inputs to the VIA chip high. I would think that. in addition to the column and row selection the keypad would have to pull these lines low.
I do not see any additional connections on the MPU schematic though. Can someone that has a keypad shed some light on this? Thanks |