(Topic ID: 196900)

Tech: WPC-95 CPU

By DocRotCod

6 years ago


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  • Latest reply 6 years ago by noflip95
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#20 6 years ago
Quoted from DocRotCod:

Ok maybe I found something. Per the schematics, on J201 I/O Extend my pins that are suspect go like this:
Pin 11 -> U2 Pin 18
Pin 13 -> U2 Pin 16
Pin 15 -> U2 Pin 3
Here how mine tones out:
Pin 11 -> U2 Pin 16
Pin 13 -> U2 Pin 3
Pin 15 -> U2 Pin 18
Is there an error in the schematics I'm looking at or have I found something?
Here are the schematics I am referencing:
http://arcarc.xmission.com/Pinball/PDF%20Pinball%20Misc/Williams%20WPC-95%20Schematics%20Manual.pdf

Warning with the WPC-S and WPC-95 schematics : there is many errors inside

Some noticeable:

On WPC-S : if you look at the Security PIC connections, you can notice that the labels for the pins SW ROW/SW DIR on ASIC are inverted, fortunately the pin numbers are correct. This error has been corrected on the WPC-95 schematic.

On WPC-S, the data bus on U24 (74LS374) is not wired as mentionned: the nibbles D0..D3/D4..D7 are inverted ! Of course, the pin numbers are wrong but the bus is correctly connected to the CPU (D0 goes to D0 ). There is no error on WPC-95, as U24 has been replaced by a 74LS574, with a more friendly pins placement.

About J201 : YES, THERE IS ANOTHER ERROR HERE, not corrected on WPC-95 schematic.
Indeed, for J201 the correct pins connections are:

Pin 11 -> U2 Pin 16
Pin 13 -> U2 Pin 3
Pin 15 -> U2 Pin 18

I have checked this on a normal WPC-95 board and also on the WPC-95 prototype board. Both have the same wiring, so, the WPC-95 schematic has also errors here.

Surprisingly, the WPC-S schematic has no error at this point.
The U2 pin in/out is correct. A7 arrive on pin 4, A6 on pin 17, A5 on pin 2.
And of course... this is also wrong on the WPC-95 schematic (A7 on pin 2...)

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