WPC Test Rig
On Mon, 5 Dec 2005 10:54:36 -0500, John Wart, jr
> I quickly realized that I have a ton of work to do on boards alone. I have a
> half dozen or so WPC and WPC-S project games that need all the usual board
> fixes done and some that need more advanced stuff.
>
> I’d like to build some sort of a rig I could put near my workbench to easily
> pop boards in and out and test them. Ideally, the rig would be small enough
> that I could tuck it away somewhere when I’m not using it.
I’ve seen people use a backbox from a donor game for this, usually with
various extentions and bits and pieces bolted on to the sides for various
things.
I went a different way and built a cabinet to house everything I wanted
in my test bench. It’s not perfect, and there are a few things I’d do
differently, but it’s worked out pretty well for me overall.
> I noticed in the TOP 7 DVD that Clay has built his own test rigs for
> DE/Sys11, WPC and several other generations. I’d like to do something
> similar, if I could figure it out.
It’s not really all that complicated. It gets harder if you’re trying
to generalize some of your test gear to multiple types of games, but
still, you’re dealing with a few basic needs:
1) Display(s) – gotta be able to see what’s going on here. If you only
need one type of game (DMD, etc.), then a mounted display for that
kind of game is pretty straightforward. If you’re doing multiple
types of games, or supporting games with 6- and 7-digit displays,
then it gets a bit more complicated.
2) Lamps – you’ll need something to act as your controlled lamps.
Depending on the game type(s) you’re dealing with, your lamps may
be matrixed, or may be direct controlled. You’ll need to wire up
a harness, and something on the end to light up. Some guys use
#44 lamps and sockets. To save space, I used LEDs on mine.
3) Solenoids – Plus any associated bank switching relays or anything
like that. Again, you need something here. Some guys, like Clay,
use a solenoid to provide the same kind of load the game will. I
just used a bunch of LEDs. I have yet to see a board that can drive
a LED that can’t drive a coil, but I mainly work on Zaccaria boards.
4) Sound – You need at least a speaker. You don’t need much here, so
a cheap PC speaker can be a donor, or you can buy a cheap speaker
from your favourite local discount source.
5) Switches – While I like Clay’s setup with 64 individual switches,
most of the time I’m just checking to ensure that the game can see
all 64 of them and am not troubleshooting a complicated multi-switch
problem where I need more than one closed at a time. I’ve designed
(but not yet built) a simple circuit I can plug in to the switch
matrix connectors that will simulate a switch closure for each of
64 switches running in a loop.
If you generalize your connectors, you can use much of this for various
game eras and types. The switch matrix works pretty much the same way
on pretty much all pins, so a general 64-switch box with a ribbon cable
output and some connector options will work with WPC as well as other
games.
Playfield posts with wood threaded studs make good board mounting
hardware. I found some knurled brass thumb-nuts that fit the machine
threads on the studs so that I can fasten the boards in place. I also
added some ground strap coming off the edges in places to provide a
convenient place to attach the ground lead of a ‘scope or logic probe.
I’m also adding some additional test boards and features based on things
I’ve found to be useful, ideas borrowed from other guys (Leon, Clay,
Steve C., etc.), or that I just think would be helpful. Some of this
isn’t done yet.
Dedicate one set of known-good boards to your test fixture. That way,
you can swap in a single unknown board and know that the other boards
are not a source of the problem. Don’t use these boards for your other
games, or to loan out to a friend to get his game running. Keep them
for your bench. On mine, I’ve fitted the commonly changed sockets with
ZIF sockets (ROMs, processor) so as not to have to keep prying chips
out of machine-pin sockets. I’ve also changed all solder-in jumpers to
either DIP switches or to individual machine-pin socket pins with some
wire jumpers that can be inserted.
For mine, I have only one display mounted, but I have a front panel
selection switch setup so that it can be any of Player 1/2/3/4 or
Ball/Credit. I’ve seen other guys mount complete individual displays,
but I was trying to conserve some room in the bench so I didn’t do
that.
For power, get a computer power cord socket and use that. That way,
you can unplug it without having a cord laying around getting in the
way. It’s also handy to mount an inexpensive switching power supply
to provide +5/+12 for test instruments, tools, and whatever. I mounted
banana jacks on mine for this. A convenience 110V outlet might be nice
to have, too, if you need somewhere to plug in a ‘scope or similar.
I made up some ‘scope probe holders to mount on there for when I have
to set a probe down.
One really simple thing I like to have on mine is the little lamp in
the upper right hand corner that lets me know if the power is on, or
off.
> Has anyone made anything similar? Any tips/tricks/suggestions to make the
> project successful? Pics of your work?
http://www.zaccaria-pinball.com/temp/testbench/im001635.jpg
http://www.zaccaria-pinball.com/temp/testbench/im001636.jpg
http://www.zaccaria-pinball.com/temp/testbench/im001637.jpg
http://www.zaccaria-pinball.com/temp/testbench/im001638.jpg
My original idea was to make this as something I could pick up and move
out of the way when not in use. In retrospect, that didn’t work out.
It’s pretty much always set up and often in use. It’s also too heavy
and awkward to pick up and move easily, even with the trunk handles
on the sides. My new idea is to build a cart bottom for it, mount
it on wheels, and gain some storage space for my spare known-good
working sets of boards. It’ll be enclosed, with doors, and something
to hold the boards so they’re not just banging around loose in there.
Whatever you make will be a reflection of how you’re going to use it.
It will likely change over time, as you use it and find shortcomings
in your original designs and ideas, or come across new ideas that you
wish you’d thought of in the first place.
> Enough patience that I could ask
> enough beginner questions without raising your ire? I have a lot of
> questions on the subject.
Ask away. Don’t spend more time building the tool than you plan to
spend using it. You can see on mine that I etched boards for the lamp
and solenoid outputs. I wanted to learn to do that anyway, and it seemed
like a good first step before doing the more complicated board for
the switch matrix tester.
