Question #1:
I installed a PS-12232-P16DE system on my DE Back to the Future game, everything is backwards. For example, the word 'FOOTBALL' scrolls across as 'LLABTOOF'. What is the problem?
Answer:
The PS-12232 Master Display board has a 3 position dip switch. Switch 2, when in the up position, will cause this to happen. What you see would happen on any game using the PS-12232 board. Unfortunately an oversite on my part originally had Switch 2 set aside to differentiate the differences between Data East and Williams games and I reflected this desire in the silk screen tables on the back of the board. I changed the use of this switch to flip the letters as a debug feature but did not change the silk screen. The tables on the board will be updated with the release of the Revision C pcb.
Question #2:
Why on the PS-10877-BR system do you only use two ribbon cables between the driver board (PS-10877) and the display board (PS-12146)? The original system used by Williams used 4 cables between the two boards.
Answer:
The original WMS design of the D-10877 board and D-12146 for Banzai Run required 4 cables running between the two boards. Banzai Run did not use a ball/credit display. The original design of the D-10877 consisted of the traditional 61xx and 71xx HV transistor chips to drive the glass displays.
Each digit of the glass was managed by it's own strobe line. If you look at the original schematics you will notice that each strobe line was responsible for an Alpha Digit and a Numeric Digit and that the left displays (both Alpha and Numeric) had common strobes, as did the right displays. If you think in the traditional Sys 11 games, this would correspond to:
------------
|Player 1| |
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|Player 2| |
------------
|Player 3|
------------ |
------------
|Player 4|
------------ |
Having said this then you can see that using a cable in the Player 1 and 4 positions all of the strobe digits are covered. The FET transistors controlling the strobes of the LED digits are spec'd at 2 amps so even if all segments of the numeric and alpha digits were on it is well within tolerance.
So, let's think about the actual segment controls. With WMS traditional circuit design, all segment control is common between Players 1 and 2 (Alpha) and Player 3 and 4 (Numeric). So here we have the same situation, the Player 1 cable has all of the Alpha segment control and the Player 4 cable has all of the Numeric control.
The original WMS design is wonderful and took into account the technology available and the HV glass requirements, but if I was to copy and modify the original circuit to work in a 5v LED system it would have added more components, unneccessary complexity to the circuit and two additional cables.
