Mortal Kombat 6-1 jamma switcher issue

Your 6-in-1 switcher -5V mod cable is feeding all your connected MK boards at the same time. Some say that it is OK but I used another set of relays for the -5V mod of my swither.

My theory is that when all your MK boards are connected to the switcher, the power supply "might" not provide enough juice on the -5V line and shut down due to over-current protection. This might be the reason you only see your setup work for only a few seconds...


Have you tried only the switcher connected, without the PCBs connected?
 
For sure but I don't understand how I wouldn't. I can plug the cab's jamma harness directly into any pcb and play all day.

Since it works in your "other" cab, I don't suspect something with the 6in1.

You need to put it in your MK4 cab and see what is "missing" or "wrong" to figure out why it isn't working.

If you don't have a volt meter, buy one.

Put the 6in1 in your MK4 cab and check the voltages on the jamma tabs of the 6in1 where power comes in.

This is really your first step.
 
OK! This is crazy!
Measuring at the end of the jamma harness I get:

Pin 3 & 4: Just over +5v
Pin 5: -5v
Pin 6: 11.33-11.67v

NOW, as soon as I plug the jamma harness into the 6-1 switcher my power supply shuts down. Barely any voltage across the pins.
If I very slowly plug the jamma harness into the 6-1 I can get power for a few seconds until the power supply sees something it doesn't liked and shuts down.

WTH?!?? I can plug the jamma harness right into any MK board and the power supply kicks right back on.

I can take the 6-1 and plug it i to my other cabinet jamma and it works fine.

Bad or weak power supply in the MK 4??!?

Thanks.
 
This is due to a short.

Very carefully look at the contacts on your MK4 harness to see if any pins are unexpectedly bent.

I've also noticed that on some jamma connectors and some boards, it is possible to slide on the jamma connector such that the tabs don't like up perfectly.

Power everything down. Put the connector on. See if the gnd/5v/12v jamma tabs overlap each other.

Please note this could also be due to a totally different wiring issue in your cab. But, lets start here.

The good news, we know what the problem is. :)
 
Thanks again. Sorry to be such a total noob with this.

I don't see anything misaligned or flawed with the jamma harness. I'll keep looking though. I measured the pins again at the jamma harness. Should pin E (-5v) read 0 if no pcb is connected?? Actually, that pin is a thin yellow wire looking like it runs to the light bulb on both my coin slots. You mentioned that before but it was the red wire I checked. Now with the multi-meter it looks like that thin yellow pin E could be a problem?

A/1: Ground
B/2: Ground
C/3: +5.50
D/4: +5.50
E: -0.00
5: -5.10
F/6: 11.44
 
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That was it!

Pin E was being used to power my coin slots and not -5v. I gave pin E -5v and the switcher is up and running!!

I have a mess to clean up and a lot of work ahead to make it look nice now. Need to get my coin slots lite up again as well. Thanks guys!!
 
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