Mortal Kombat 6-1 jamma switcher issue

Jograzz

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Hi guys, I'm hoping someone can assist me with a MK jamma harness. I have an original MK 4 arcade that has functioned perfectly for many years. Over time, I purchased every Mortal Kombat pcb and used each one without a switcher inside the MK4 cabinet. Two years ago I learned how convenient a switcher would be so I purchased a 6-1 and had it modded by an awesome forum member here. I never could get it working as it wouldn't power up for more than a few seconds. I lost interest and it sat until this weekend. Lol

Longer story made short I discovered my MK4 jamma harness is missing the top Orange 12v pin 6 wire. I'm a total novice with this stuff but I reverse engineered using my other jamma cabinet that I have running a modded Xbox. That second orange wire is there coming from the power supply harness in my other cab and the switcher powered right up.

Why is this wire missing from my original MK4 jamma harness? More importantly, how can I wire one in to make my switcher work?! Is it as simple as putting a wire 12v from the power supply harness and into top pin6 on the jamma harness?

Sorry if this has been covered or is totally trivial. I'm a want to be hobbiest with arcades but unfortunately I've never had the time or resources to start my collection. I just grew up playing MK arcades and love owning my own as a middle aged old guy. Lol

Thanks!

Top pin 6 missing-
rh7ot0.jpg



From power supply-
nxnzx4.jpg
 
I'd have to look over a jamma 6in1 PCB, but yes, it is possible that it needed the 12v wire on both sides (or at least that side) to run its relays.

These split pins for your jamma harnesses:
https://www.mikesarcade.com/cgi-bin/store.pl?sku=CECPIN010

And the molex .093 pin for your power connector housing, to run 2x 12v wires to your jamma harness.

(Or splice into the single 12v wire to double it.)

It won't hurt anything running both to your jamma connector/mk4.
 
^Thanks.
I found it strange my original MK4 jamma harness was/is missing this pin. In order to make my 6-1 switcher power up I need this pin. So I can simply (properly) splice a 12v wire from the power supply harness and into the top pin 6?
 
^Thanks.
I found it strange my original MK4 jamma harness was/is missing this pin. In order to make my 6-1 switcher power up I need this pin. So I can simply (properly) splice a 12v wire from the power supply harness and into the top pin 6?

It MIGHT need this pin. (I don't have a 6in1 AND volt meter in hand to confirm this.)

12v has little voltage drop from the current demands of these games, so only one wire was NEEDED.

Yes, splicing that 12v wire to 2 is ok to do.

If you have the .093 molex pin (female or male based on what is in it now), it is just as easy to run a complete second wire to one pin so both jamma split pins have their own wire. Either way in this application shouldn't matter though.
 
If you want to test this before ordering parts, you can jumper a wire to your 12v power supply and hold to where the missing jamma split pin is.

You could also put the jamma connector on the 6in1 and power it up. Than volt meter (D/C) and check that this "empty" spot has 0v instead of 12v.
 
Yes, I do have spare molex pins!
Perhaps it's my power supply but the switcher refuses to run without that wire on the jamma harness. In my other cabinet that pin is wired and the switcher powered right up.

Again, this has been 2+ years in the making. When I originally tried to get this up and running I never figured out why it didn't work and it went on the shelf. After all these years I just assumed my switcher was damaged in transit but now I figured out why it didn't work. Haha
Thanks.

It MIGHT need this pin. (I don't have a 6in1 AND volt meter in hand to confirm this.)

12v has little voltage drop from the current demands of these games, so only one wire was NEEDED.

Yes, splicing that 12v wire to 2 is ok to do.

If you have the .093 molex pin (female or male based on what is in it now), it is just as easy to run a complete second wire to one pin so both jamma split pins have their own wire. Either way in this application shouldn't matter though.
 
Yes, I do have spare molex pins!
Perhaps it's my power supply but the switcher refuses to run without that wire on the jamma harness. In my other cabinet that pin is wired and the switcher powered right up.

Again, this has been 2+ years in the making. When I originally tried to get this up and running I never figured out why it didn't work and it went on the shelf. After all these years I just assumed my switcher was damaged in transit but now I figured out why it didn't work. Haha
Thanks.

Do you see that one smaller red wire for 5v on your jamma connector?

Check that that contact has 5v too. Sometimes "extra" wires were put their to provide power (for coin lamps) and the switchers needs that for power instead.

But, based on the above comment, it sounds like you are on the right track.

Edit: and double check your ground wires too I guess.
 
The pic above is of my actual jamma harness. I was trying to show top pin 6 12v orange missing.

I have a molex connector for the harness on the power supply but I do not have a push in terminal for the jamma harness. I wish radio shack still existed!
 
The pic above is of my actual jamma harness. I was trying to show top pin 6 12v orange missing.

I have a molex connector for the harness on the power supply but I do not have a push in terminal for the jamma harness. I wish radio shack still existed!

Yep, I know that was your actual picture. Still check the smaller wires for what I said.

radio shack never carried the split pin. I posted a link above to them. $3 for 10pins +shipping.
 
Yep, I know that was your actual picture. Still check the smaller wires for what I said.

radio shack never carried the split pin. I posted a link above to them. $3 for 10pins +shipping.

Will do. Thanks again!
 
on the chinese switcher I have, labeled "6WAYSW03", the 12V Jamma pins 6&F are bonded to each other by way of several vias in the PCB.
 
I patched in a +12v to pin 6 (F). No luck.
I traced the small red +5vdc pin 4 (D) back to my coin counter. I took that and temporarily patched in a +5vdc from pin 3 to pin 4 but there's no change with that either.

All the ground wires look good. I did see pin E and 27 (smaller grounds) trace back to the Player 1/2 button harnesses.

The switcher isn't powering on. I notice when I shut power OFF to the cabinet the switcher led will briefly light up. WEIRD.

I didn't have time to do much else but I'm baffled. My MK 4 cab is all original and runs perfectly. I thought I could drop this switcher in and have my dream machine MK 1-4. Lol
 
I can't see anything that seems wrong from what you're describing. Could you try the switcher in another cabinet? Or could you attach front and back pictures of the switcher, and I could take a look?
 
Thanks guys.
I won't be able to validate with a multi-meter until tomorrow night.

I tried the switcher in my converted jamma cabinet and it works just fine. The one it works in is a midway converted MK 3 that now runs a Coinops 8 Xbox. Power supply is a Powermaster111 150w 10amp.

It's the original MK 4 cab the switcher refuses to run in. Power supply is an original Peter Chou but it seems to still run great.

Pics of my Chinese switcher:

duvqr.jpg

e1dnde.jpg
 
My guess is that the voltage in your MK4 cab isn't high enough to operate the 6in1 PCB (for whatever reason).

Check the voltage of both cabs when a game is running.

If the MK4 cab is lower, bump it up. 5.2v at the 6in1 PCB is ok.

If no game is attached, the voltage may meter higher, that is normal and ok. (That is why you want to check the voltage under load.)
 
This switcher really only cares about the 12V buss to operate. The 5V buss is only sent directly to each of the jamma ports via their associated relay.

It's very tolerant of a very wide range for the 12 Volt supply, and I have personally seen it work just fine with the 12V buss set as low as 8 Volts and as high as 15 Volts.
 
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