Mortal Kombat II [2] Revision 2.1 Having Issues

[Bradley.Lusk]

Hello all,
I recently purchased an original MKII arcade that worked fine for a few weeks and then crapped out on me. I'm hoping you guys can offer some insight, suggest a place to get a fix-up (I live in Mesa, AZ), or help me fix it myself.

The problem is as follows:
Whenever I boot up my system and run the system diagnostic, the roms on the right hand side of the screen are red (Roms U6-U13). After this screen I get a message that says 'Errors Detected' and 'CMOS invalid- factory setting restored.' If I try to play the game, all of the video and player animation is choppy to the point of the game no longer being playable. See pictures for screen shots.

Any advice is most appreciated.
Cheers,

Bradley Lusk

[Spyridon]

I'd start by reseating the chips that are marked as bad.  If the error still continues, replace them.  Hobbyroms can probably provide you with the roms you need.

[Q*Bert_OP]

Pull the daughter card off of the cpu and reseat it. There should be a plastic standoff to hold the daughter card to the mpu board. As far as the CMOS error, check the coin cell battery on the MPU.

[Malenko]

those roms are on the daughter card, to get rid of the CMOS just change the dip switch to use dip instead of CMOS. You'll still need to replace the battery if win streaks mean anything to you

[Bradley.Lusk]

Thanks for the advice guys. I've never worked on an arcade before. So I have the daughter card off, but I do not know how to reseat. How do I reseat and for what should I be looking? I have attached a picture of the board.

[Q*Bert_OP]

See attached picture. Remove the board I'm pointing to, and re connect it.

If you don't  have that board, one of the "not used" dipswitches tells the CPU if it is to be used or not, and yours might be set wrong.

[Bradley.Lusk]

Thanks for the help! The video is now working fine; however, now the audio doesn't want to work. I did a sound check and the system says all the boards and roms are fine and I still hear the beep during boot-up. Perhaps I reconnected something incorrectly. How should the smaller card with the sound roms be reconnected to the main board? I have attached a picture to show how I currently have the boards connected.

[Q*Bert_OP]

Make sure the ribbon cable between the sound board and CPU has the red striped side going to pin 1 on both the CPU and sound board.

[Malenko]

What do you hear during boot up? a single tone? a single tone means all checks passed. Any errors on screen? if its CMOS error, change the battery or adjust the dips to do the settings via dip instead of CMOS

[Bradley.Lusk]

I changed the ribbons up and now everything is working great. I have never been to a forum more helpful than this one. Thanks guys/gals!

Bradley

[Q*Bert_OP]

Make sure the ribbon cable between the sound board and CPU has the red striped side going to pin 1 on both the CPU and sound board.

And I shall explain why you'd still hear a tone with the ribbon cable flipped...

The CPU and sound board both contain CPUs. They run as two separate computers. The CPU gives commands to playback sounds to the sound board through the ribbon cable. Since the sound board is independent of the CPU, it can be tested to a certain extent on a bench without the main CPU board present, and you can hear tone(s) if a speaker is connected.