Medieval Madness Williams WPC-95 A/V Board no display

Post by Jose Carlos Lucas
Hello,
I have MM and had a problem with DMD, not displaying anything. HV section of the WPC-95 A/V board was rebuild and I have all tensions ok on the DMD, -116V; -104V; +5V; +12V and +65V all good. The DMD was tested on another machine and works without any problem. The machine starts the game, I can hear the sound and play normally but nothing is showing on display. Anyone have some tips? If need any more information, just let me know.
Thanks.

I'm reading you should have on the order of -125, -113, +5, +12, +62. your -116 and -104 may be too low to excite the display. check the voltage on the machine you tested the DMD in - if they're higher then yours, that may be why it's working there.

k***@yahoo.com

2018-01-10 04:36:48 UTC

Post by k***@yahoo.com

actually, it seems later WPC games used -112 -100, early games -125 -113.

while your voltage is within spec, you might have a weak display that needs the extra voltage. that's why you should check the voltages in the game it works in.

I've seen DMD controller boards where someone hacked in an extra zener diode to bump up the voltage and make a dead display work again. not a long term fix, but shows a weak display may work on higher voltage.

also, if your display was working, then you rebuilt the HV and now it doesn't, then your board before may have been providing a greater voltage before.

DomaineR

2018-01-11 06:01:44 UTC

I would check your voltages on the dmd board and down a trace away from the pins. My mid 90's pins are suddenly getting all sorts of cold solder joints and in places not directly 'in the line of fire'. While it wasn't surprising in the saucer board on an AFM, it was on some driver boards components (non connector) on a TOM

Also, not a bad idea to see if you can borrow a dmd from another machine. But that is often easier said than found.

Jose Carlos Lucas

2019-01-25 03:05:58 UTC

I would check your voltages on the dmd board and down a trace away from the pins. My mid 90's pins are suddenly getting all sorts of cold solder joints and in places not directly 'in the line of fire'. While it wasn't surprising in the saucer board on an AFM, it was on some driver boards components (non connector) on a TOM
Also, not a bad idea to see if you can borrow a dmd from another machine. But that is often easier said than found.

Hello, I tested the display on other machine and works fine. Tested other DMD on the affected machine, but still no video. The only thing that happens is when the machine powered off the display show some lines than off.

Thanks.

LexingtonVAPin

2019-01-25 13:59:28 UTC

I would check your voltages on the dmd board and down a trace away from the pins. My mid 90's pins are suddenly getting all sorts of cold solder joints and in places not directly 'in the line of fire'. While it wasn't surprising in the saucer board on an AFM, it was on some driver boards components (non connector) on a TOM
Also, not a bad idea to see if you can borrow a dmd from another machine. But that is often easier said than found.

Did you try switching the ribbon cables with another pin? The ribbon
cables involved are those going from the CPU to the DMD controller, and
the ribbon cable from the DMD controller to the DMD itself.

Also be certain that the ribbon cables are plugged in properly. I find
that it is frustratingly easy to get a ribbon cable off by an entire
row. And I had a pin where someone had substituted a non-standard
ribbon cable that had more positions than the correct one, and I was off
by a column.

It would be nice if you had another WPC95 around where you could switch
out boards to troubleshoot.

--
http://orcalcoast.com/

Jose Carlos Lucas

2019-02-10 17:14:50 UTC

I would check your voltages on the dmd board and down a trace away from the pins. My mid 90's pins are suddenly getting all sorts of cold solder joints and in places not directly 'in the line of fire'. While it wasn't surprising in the saucer board on an AFM, it was on some driver boards components (non connector) on a TOM
Also, not a bad idea to see if you can borrow a dmd from another machine. But that is often easier said than found.

Did you try switching the ribbon cables with another pin? The ribbon
cables involved are those going from the CPU to the DMD controller, and
the ribbon cable from the DMD controller to the DMD itself.
Also be certain that the ribbon cables are plugged in properly. I find
that it is frustratingly easy to get a ribbon cable off by an entire
row. And I had a pin where someone had substituted a non-standard
ribbon cable that had more positions than the correct one, and I was off
by a column.
It would be nice if you had another WPC95 around where you could switch
out boards to troubleshoot.
--
http://orcalcoast.com/

Tested on other machine and A/V board and cables are 100%. The problem is on CPU board, already replace the U2 74LS244N, but still no video.

Thanks.

LexingtonVAPin

2019-02-10 19:46:03 UTC

I would check your voltages on the dmd board and down a trace away from the pins. My mid 90's pins are suddenly getting all sorts of cold solder joints and in places not directly 'in the line of fire'. While it wasn't surprising in the saucer board on an AFM, it was on some driver boards components (non connector) on a TOM
Also, not a bad idea to see if you can borrow a dmd from another machine. But that is often easier said than found.

Did you try switching the ribbon cables with another pin? The ribbon
cables involved are those going from the CPU to the DMD controller, and
the ribbon cable from the DMD controller to the DMD itself.
Also be certain that the ribbon cables are plugged in properly. I find
that it is frustratingly easy to get a ribbon cable off by an entire
row. And I had a pin where someone had substituted a non-standard
ribbon cable that had more positions than the correct one, and I was off
by a column.
It would be nice if you had another WPC95 around where you could switch
out boards to troubleshoot.
--
http://orcalcoast.com/

Tested on other machine and A/V board and cables are 100%. The problem is on CPU board, already replace the U2 74LS244N, but still no video.
Thanks.

Just to clarify, you tested the A/V board and all ribbon cables on
another pin and they all work? Or, conversely, you switched the CPU
into a working machine and still no DMD?

Jose Carlos Lucas

2019-02-10 21:34:20 UTC

I would check your voltages on the dmd board and down a trace away from the pins. My mid 90's pins are suddenly getting all sorts of cold solder joints and in places not directly 'in the line of fire'. While it wasn't surprising in the saucer board on an AFM, it was on some driver boards components (non connector) on a TOM
Also, not a bad idea to see if you can borrow a dmd from another machine. But that is often easier said than found.

Did you try switching the ribbon cables with another pin? The ribbon
cables involved are those going from the CPU to the DMD controller, and
the ribbon cable from the DMD controller to the DMD itself.
Also be certain that the ribbon cables are plugged in properly. I find
that it is frustratingly easy to get a ribbon cable off by an entire
row. And I had a pin where someone had substituted a non-standard
ribbon cable that had more positions than the correct one, and I was off
by a column.
It would be nice if you had another WPC95 around where you could switch
out boards to troubleshoot.
--
http://orcalcoast.com/

Tested on other machine and A/V board and cables are 100%. The problem is on CPU board, already replace the U2 74LS244N, but still no video.
Thanks.

Just to clarify, you tested the A/V board and all ribbon cables on
another pin and they all work? Or, conversely, you switched the CPU
into a working machine and still no DMD?

I tested the CPU and A/V board on another working machine. The tests were, with a know good CPU board my cables, my A/V board, and DMD, working 100%. With my CPU board no video on DMD, with my or other DMD also tested with another A/V, still no video.

Thanks.

Bay78

2023-11-01 05:53:04 UTC