Using a printer switcher for Multi JAMMA...how?

elekTRONarcade

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I've heard rumors of people using a DB25 printer switcher as a JAMMA switcher, yet have found very little info on the subject (aside from Niobium's great yet very complicated write-up over at arcadezone.org). So here's my question: Would it be possible just to hack up one JAMMA harness (for input), multiple JAMMA extensions (for outputs), wire them to DB25s and use a straight printer switcher like this one? http://www.buy.com/prod/belkin-4-po...lkin-slimswitch-5-x-db25-female/10007729.html

That's the switcher I have. My thought is, to wire up everything except the +5, -5 and 12v lines to the input/outputs, then install separate switches for the power lines. While the power switches are off, move the main rotary switch to the board you want, then reapply power (to avoid the issue of having more than one board powered up while in mid-position while switching the rotary). The rotary switch completely isolates the lines from each position, so having the switch set on 3 and powered up powers only that board and not all of the others at once.

Does any of this seem feasible or worth the time/effort?
 
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You could probably get away with switching control, sound and video lines with a printer switch, but switching power would need something a bit bigger.

Why not just buy Clay's multi jamma?
 
You could probably get away with switching control, sound and video lines with a printer switch, but switching power would need something a bit bigger.

Why not just buy Clay's multi jamma?

Probably because the OP isn't interested in spending $150 on it, and wants to roll his own.

I like this idea. Do it!
 
lol Actually I toyed with the idea of using Clay's. Prob is, he no longer makes them, so finding the boards would be difficult (plus like smalltown said, the price is a bit overboard). I had until recently been using a 6-in-1 from Yaton, but there were too many sync issues between different game boards. My belief has been that the way boards like Clay's and the Yaton switchers are set up, they introduce unwanted noise in the sync lines. Whenever I've ran each game board straight in my cabinet, I haven't had to make any adjustments to the monitor from one board to another.

My theory (that I'm hoping someone can confirm before I burn up any boards) is that by using the printer switch, it will act as a single JAMMA harness with selectable outputs, making it purely a passthru for the signals. Since the other switchers (like Clay's, the 2-in-1 and 6-in-1s, etc) are powered boards, they may be introducing excess noise and decreasing the voltage output going to the JAMMA boards plugged into them. In a way, its just another mouth for the power supply to feed. The printer switch inside is nothing but a bunch of wires and requires no external power.
 
Here are some pics of the inside of the switcher

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I can see what your wanting to do in my head... but I don't think it's possible, without actually hacking into other wires.

25 pins each, well damn.. 2 players, 3 buttons each 2 start buttons.. 18 wires used.. 5 monitor wires, 23 used.. 2 speaker wires = 25...

Still missing the test/service switch, coin switches.. ground wires.. i'm sure there might be another thing or two i'm missing..

If the plans were for only a one person arcade then you would have the extra wire space for the things you need..
 
I can see your point, given that the DB-25 is only 25 pins, whereas JAMMA consists of two rows of 28. However, since the switch acts as a passthrough, shouldn't it (in theory) be possible to use the same principle, with JAMMA connectors instead of DB-25s, and a rotary switch with more pins?
 
Cant see why it wouldn't work, just mechanical switching of low voltage/current signals anyway. Use looped gnd therefore only 10 wires per player. Beef up the rotary switch to 10A and you should be ok on power too although power switching would introduce its own problems.

Andy.
 
I too have considered this. But then before I knew it I had a shit ton of boards.

So I ordered a 3 foot jamma extension harness, and I should get it tomorrow.

I will put all my jamma boards on a rack next to the cabinet and run the harness out the back and then switch them 1900s telephone operator style.
 
Or if you have the right kind of cabinet you can do it manually where it'll be easy and 100% glitch free.

I ran the cabinet's jamma connector up to the control panel in my Gauntlet Legends (top swings up), ran jamma extension harnesses from Gaunt Leg and NBA Jam up to the control panel, and when I want to switch games I just pop the top up, power the game off, swap 1 jamma cable, and 2 Molex 9 pin cables for P3 and P4 controls and I'm done.

It takes about 20 seconds to switch games and it's all easily done from the control panel. Granted, I usually have to tweak the monitor remote board to optimize the picture with the other board but I've run the monitor remote control board to the CP as well so that takes maybe another 10 seconds.

You have to have the right kind of control panel for this to work and use quality jamma extension harnesses (not Jammaboard's).
 
Should work fine, just make sure the switcher is passive, and deal with the power lines via a chunkier switch.
 
I can see what your wanting to do in my head... but I don't think it's possible, without actually hacking into other wires.

25 pins each, well damn.. 2 players, 3 buttons each 2 start buttons.. 18 wires used.. 5 monitor wires, 23 used.. 2 speaker wires = 25...

Still missing the test/service switch, coin switches.. ground wires.. i'm sure there might be another thing or two i'm missing..

If the plans were for only a one person arcade then you would have the extra wire space for the things you need..

That's my thought as well. JAMMA connectors are two rows of 28 = 56 total. Not counting the unused pins, keyslot and Neo Geo 4th button pins, that leaves 41. The eight grounds can be combined into one, as can the two +5v, -5v and +12v lines respectively. So after all that, I think it's closer to 31 pins (top and bottom) that would need to be wired up.

Cant see why it wouldn't work, just mechanical switching of low voltage/current signals anyway. Use looped gnd therefore only 10 wires per player. Beef up the rotary switch to 10A and you should be ok on power too although power switching would introduce its own problems.

Andy.

That's what I'm concerned about, is the power problems. Chatter caused by contact bounce can't be good for logic circuits, not to mention potential arcing issues or possible voltage drops/spikes from simultaneous momentary contact between two positions. If it were a break-before-make switch, then there wouldn't be so much of a worry.
 
What I see in my head, may be different then what your thinking. If you do go ahead and attempt this, I'd like to see how it turns out. I guess there's some key part that I'm overlooking or just not processing..? But good luck with it!

I can see your point, given that the DB-25 is only 25 pins, whereas JAMMA consists of two rows of 28. However, since the switch acts as a passthrough, shouldn't it (in theory) be possible to use the same principle, with JAMMA connectors instead of DB-25s, and a rotary switch with more pins?

Apparently I did miss a big piece of the puzzle.. If your just using the rotary switch, and adding the extra pins then it should work fine. Keeping the power separate, I see this working fine.
 
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I too have considered this. But then before I knew it I had a shit ton of boards.

So I ordered a 3 foot jamma extension harness, and I should get it tomorrow.

I will put all my jamma boards on a rack next to the cabinet and run the harness out the back and then switch them 1900s telephone operator style.

Or if you have the right kind of cabinet you can do it manually where it'll be easy and 100% glitch free.

I ran the cabinet's jamma connector up to the control panel in my Gauntlet Legends (top swings up), ran jamma extension harnesses from Gaunt Leg and NBA Jam up to the control panel, and when I want to switch games I just pop the top up, power the game off, swap 1 jamma cable, and 2 Molex 9 pin cables for P3 and P4 controls and I'm done.

It takes about 20 seconds to switch games and it's all easily done from the control panel. Granted, I usually have to tweak the monitor remote board to optimize the picture with the other board but I've run the monitor remote control board to the CP as well so that takes maybe another 10 seconds.

You have to have the right kind of control panel for this to work and use quality jamma extension harnesses (not Jammaboard's).


My main concern with doing it either of these ways is the potential wear-and-tear damage to the edge connectors over time from constant switching.
 
Well, here we go..the guts of the switcher. I'm hoping someone can identify what type of rotary switch this is or where to buy them at. It's a four position switch with 7 decks and 28 terminals per deck. Belkin unfortunately snipped off unused terminals. There are no numbers or identifiers printed on the switch.

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Nothing to worry about.

Yeah, Bob Roberts (it's his jamma extension cables that I sprang for) said he'd been using the same one for many, many years and hadn't had any problems.

If I switch my game back and forth 20 times a year I'd be surprised. I think something else will fail long before then.
 
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