WMS Reel Slot - Errors: dot FAIL, Buffer Overflow

[PaulV]

History of problem at http://newlifegames.net/nlg/index.php?topic=7661.0

Basically, dot FAIL on LEDs and/or Buffer Overflow on Dotmation display most likely indicate a failure to communicate on the serial line between the lower CPU and the Dotmation controller. The serial path leads from the main CPU board, to the Backplane Board, then to the Dotmation controller via a cable.

First check power is OK on upper and lower power supplies.

Then check that the serial cable is not loose at either the Backplane or Dotmation Controller, pictures below.

If you don't have spares boards to swap out and try, you may need to attempt a board repair.

The problem I found was with the capacitors of the RS232 interface chip. Replacing these caps resolved my problem.

My bad caps (only 1 was bad) were on the main (lower) CPU board. They could have just as well been on the Dotmation Controller board, a failure either place will shut down the serial connection.