6-in-1 Jamma Playchoice-10 mod for common LED timer

[ebo0763]

I plan to hook up 3 Playchoice-10 single monitor PCBs on a 6-in-1 Jamma Switcher. One problem is that if I want the LED timer to display for all PCBs, the jamma switcher is not enough. So I thought of making a circuit based on the 6-in-1 Kick harness mod. I can't find more info on the LED pcb so I might be wrong here.

Here's a close up picture of the LED pcb: http://img542.imageshack.us/img542/9369/playchoice10ledpcbpck1l.png

Only one PC10 pcb at a time is powered. I assume GND doesn't need a diode right? Let me know what you think. BTW, PC10 has two edge connections, I disgarded the one not necessary for this circuit.

[MonMotha]

The LEDs aren't directly hooked up to those signals.  It's actually a little latch/address system with digital inputs, so you need push/pull signals.  If you want to use diodes, you'll need to put a pull-down resistor (~1k to ground) on each line on the LED board side of the diode configuration, and then it's essential that the JAMMA switcher powers down the unused boards.  Also, use type 1N4148 (or 1N914), not 1N4001.

However, the easiest way to do this is probably with some tri-state buffers.  Handily, you've got exactly 8 signal wires (4 data, 3 address, and a latch signal), and buffers are readily available in an 8-wide configuration.

The best part number is probably a 74HC541.  They're cheap (about 60 cents each), and you'll need 3 (one for each board).  Just hook the 8 signal lines up to the inputs on each buffer, hook the outputs of the three buffers together and on to the LED board.  Apply 5V/GND to the buffers and to the LED board (you can just re-use the 5V/GND that are part of that 12P harness).

You then need a way to signal the buffers.  There are two enable lines, both active low, and they both need to be low for the buffer to be enabled.  You only need one, so just tie one of them to ground.  You then need a 5V logic signal for the other side.  If your JAMMA switcher switches power you can just get a 74HC14, hook the 3 power lines up to three of the inputs (ground the other three) and use those as your enables for each buffer.

It may be a decent idea to put ~47ohm series resistors on the output of each buffer (before they all get tied together) to make sure things don't break if there's a short overlap where both are enabled.

Should be easily built on a piece of stripboard (aka veroboard) or perfboard.

[ebo0763]

Just to clarify, those LED signals don't go through the Jamma switcher but they come straight from the game pcb. And only one game at a time will be turned on.

That sure sounds like a good idea but I have a hard time picturing the circuit... I never used IC chips before so please bear with me. That's what I was able to figure out. Is it posssible for you to complete this circuit? And correct me if I'm wrong. As you can see I don't understand the 5V part... Except I want the LED pcb to be powered only if it's a PC10 is powered, because I'll use other games too.

[MonMotha]

You're very close.  You can just pull 5V straight off your cabinet power supply, rather than from each board, but using diodes like you show will also work.  Again, I'd use a 1N4148 rather than a 1N4001, but it doesn't much matter for a simple power line like this.  You can use this same supply for the LED board, too (it'll always be on).  Basically, the chips and the LED board need to have power all the time.

The resistors on the outputs of the chip are series, not to ground - i.e. they serve to isolate each chip from the common point where it connects to the LED board.  They're not strictly required, but they may save things in the event you accidentally turn on more than one buffer.

Your HC14 would be powered from the same place as your HC541s and LED board.  You'd hook up to each input on the HC14 (the "A" ports) the switched 5V from each playchoice board.  The output would then be the opposite state (i.e. 0V when the board is on, 5V when it's off), so you can use that to control the buffers.

I'll see if I can get this drawn up for you.

Now, one thing I did think of: you do realize that playchoice isn't actually JAMMA, right?  It's close, but I don't know for sure that your switcher will handle it right.

[ebo0763]

Basically, the chips and the LED board need to have power all the time.

Well, only when I'm playing pc10 games, I will also have other slots to play VS games. In this case, I want the LED off. So should I take the 5V only from the PC10? I mean, it can be off while I'm playing other games.

Your HC14 would be powered from the same place as your HC541s and LED board.  You'd hook up to each input on the HC14 (the "A" ports) the switched 5V from each playchoice board.  The output would then be the opposite state (i.e. 0V when the board is on, 5V when it's off), so you can use that to control the buffers.

I'll see if I can get this drawn up for you.

Ok yeah this part I don't get... 

Now, one thing I did think of: you do realize that playchoice isn't actually JAMMA, right?  It's close, but I don't know for sure that your switcher will handle it right.

I will make custom Jamma finger boards. It's just rearranging the pinout. The video colors are inverted but that shouldn't matter right? The only thing I'm wondering is if the the audio will work through the switcher since Jamma is usually amplified while nintendo isn't. So I'm hoping that by just sending the output of the switcher into the sound amp it will sound fine. Otherwise I need an amp for each slot... or not! I think one of those mad scientist circuit could let me use only one amp right? there must be a way, but that would be the topic of another thread. I'll wait until the LED circuit is finished.

[ebo0763]

I'll see if I can get this drawn up for you.

That would be really appreciated. Just draw over my image.

[ebo0763]

Bump

[lilshawn]

find yourself a program called "Livewire" it's a circuit simulator program that works really great.

that way you can build a circuit and test it before you ever solder a single component.

[ebo0763]

find yourself a program called "Livewire" it's a circuit simulator program that works really great.

that way you can build a circuit and test it before you ever solder a single component.

Very cool.

[ebo0763]

Heres what my friend has come up with.

Quote: "I did not include the mutual exclusive stopper, it is possible for more than one board to be active at one time. According to one of the posts the resistors should be sufficient. The little unidentified rectangles are resistors. If you zoom in you will see that they are colour coded for 47ohm"

[xray2]

You only need 1 set of pull-down resistors in the circuit.  Did not dig any deeper after seeing that.
   

Heres what my friend has come up with.

[ebo0763]

Ok so I know it's been a while, but here's an update. Let me know what you think.