Mortal Kombat 2 Cmos invalid error

TechnoFreek

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Hi recently acquired an mk3 revision 3.1 board. At first the image was unstable and kept resetting so I had the turn up the 5v supply a notch. Sorted.

Next issue is that when I power on the board I get the cmos invalid, factory settings restored, dipswitch coinage used error. Needless to say my settings and stats don't save on power off.

A quick peek around the board and I found that there was no battery at all. I took the battery from a faulty mk1 board, metered it at 3v and stuck it in my mk2 board.

I still get the same error after putting in the battery. Oddly though if I go into the test menu, make my adjustments and exit back to the game I get a CMOS OK, dipswitch coinage message.

Switch off the machine and I'm back to the cmos invalid message.

Any ideas? Thanks
 
Check the battery voltage at the chip.

Check for corrosion or bad contacts on the battery holder.
 
Sometimes, when you replace the battery, you need to leave the board on for a little while to "charge" the CMOS chip. Try leaving it on for 10 minutes or so, then turn it off for 10 minutes, then back on to see if your error has gone.
 
I've also had to hit the little reset button and or do a full factory restore via the test menu (not sure which one it was i'd start with the button first unless you don't mind losing saved scores).
 
Cheers guys. Some good advice there and while I'm not in the house at the moment, I think I recall seeing some corrosion on the top flap type contact.

Will meter the holder outputs for 3v and take it from there.

Will report back.
 
My vote is the battery buddy. I know these guys have guided you there already, but just to add to that, I was getting that error with a dead battery on my Jam. If you see corrosion, I would definitely focus there. Good luck.
 
Right. Metered 3v at the battery holder so that seems ok. Where is the CMOS located and where do I measure from?

Also having machine on for the charging scenario.
 
Right. Think this is sorted. Either the full factory reset or charging the cmos or both fixed the issue.

Thanks everyone for their help!
 
I wish I hadn't tried both at the same time but I'm leaning towards the cmos charging solution myself.

I'm pretty sure that I had already tried the full factory reset previously.

Thanks either way.
 
Yea, I'm going to be that guy and necro a 10+ year old thread.

I just had this exact situation happen to my rev3.1 MK II... came here looking for help and found it... I wanted to address the two test case scenarios discussed towards the tail end of the thread.

In my situation, all I had to do is swap the battery, waited for 15 minutes, powered down the game, waited for 10 minutes, and powered it back up and no more CMOS error. I did not have to hit the reset button on the board or perform a factory reset within the service menu... so I guess @zenomorp wins it :LOL: -- He can finally rest easy after all these years knowing he was correct on this one.

I'm so thankful random old threads like this exist. This isn't the first time I've gotten @zenomorp help... I've bugged him on Facebook a few times as well.

Addendum: I checked and got 3v at the new battery as well... the old battery (outside of the board battery housing) was reading 2.2v when testing it... it was time for the old battery to be retired.
 
Yea, I'm going to be that guy and necro a 10+ year old thread.

I just had this exact situation happen to my rev3.1 MK II... came here looking for help and found it... I wanted to address the two test case scenarios discussed towards the tail end of the thread.

In my situation, all I had to do is swap the battery, waited for 15 minutes, powered down the game, waited for 10 minutes, and powered it back up and no more CMOS error. I did not have to hit the reset button on the board or perform a factory reset within the service menu... so I guess @zenomorp wins it :LOL: -- He can finally rest easy after all these years knowing he was correct on this one.

I'm so thankful random old threads like this exist. This isn't the first time I've gotten @zenomorp help... I've bugged him on Facebook a few times as well.

Addendum: I checked and got 3v at the new battery as well... the old battery (outside of the board battery housing) was reading 2.2v when testing it... it was time for the old battery to be retired.
Do the nvram mod and eliminate the battery foreva!!!!
 
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