Unique Pin Out - Where do I start?

[lesoleil70]

Hi,

I've picked up a few pcb's over the last 12 months that have unique pin outs, with no information on KLOV etc.  Some of the boards I've got, I've no idea what game they are.

I'm talking boards that I've got for silly cheap money, been given, traded, or were laying in the bottom of dead cabs etc. Quite a collection of crap that I'd like to just figure out.

What I was hoping to do here is have a fingerboard to jamma. so whatever these boards are, I can plug n play them.

Where do I start/what do I need to be able to identify:-

12v
-5v
+5v
gnd

sync
r
b
g
ground

controls

The one I'm interested in getting going first is a game that I DO know the identity of, it's a Blood Bros clone called West Story, the board is by Datsu. It's not Jamma, but it is 56 pin.

Here are some pics.  

All help appreciated.

Ian you once told me how to do this...I wrote it down and lost the paper when I was in the middle of all the other cabs- I know that's just as crappy as "
my dog ate it", but it's true.

[iankellogg]

Power will be easy enough to find out.
Follow the large copper traces to a cap or something that you can tell polarity on. Then try to find if they go right into a chip or not. that will be your gnd and +5v
+12V usually is used in audio amps so try to find the audio circuit and trace back. Audio pins will be the same way, find the output chip and follow it back to the connector.
As for inputs, look for buffer chips or pullups or something common for inputs. once you know which are inputs you can fire the game up and just trigger the buttons to find out what they do.
Video is going to be a little bit tougher but not impossible. if you can power the game up and you have a probe you can start looking for your vsync and possibly video signals. Best bet will be trying to figure out what circuits are video output and follow it back. not that easy to do if you dont know what you are lookign for.

[lesoleil70]

Cheers Ian, I'm with you all the way up until buffer chips and video.

I've defo got the power.

This would be a great video for someone to post up, I bet I'm not the only one in this position.

[iankellogg]

look for a bunch of resistors or a vertical mounted chip with like 8 or more pins in a single line. Maybe a a chip with the numbers 74LS74 or 74LS374. Those are very common for input circuits.

For the video signals the best I can think of right now is maybe taking your multimeter on maybe AC mode and try to check each pin for a voltage of around 1-2V. That is most likely the video signals. Thankfully if you find a pin with a voltage of around 1-2V you can hook that to the monitor and it won't damage it. The sync signal is a little bit more difficult to find. Best bet is with a logic probe and listen for the beeps, There should be no other pin that beeps rhythmically

[lesoleil70]

Hey I got one!

Blood Bros (West Story is playing)  The video was a bitch, but the voltages were fluctuating and throwing me off.  Kinda makes sense now though, so was the picture in attract when it was going through the screens, the voltages were changing, I bet you are all rolling your eyes at this but but when the penny dropped for me it was like DUH!. But when I took the time on the pins with the meter they were going in cycles over a few mins.  I got RGB all backwards but got a pic then just worked from there, only 6 combos anyway at worst. the board has so many mini crocodile clips on it right now.


 This board is weird.  Jamma power settings all in the right place, and the rest is a mirror image L-R.  I'll have to document this one for KLOV after I get the audio and buttons going.

Cheers!