2 Mortal Kombat sound board problems

kidrivers

Well-known member

Donor 4 years: 2012, 2015, 2017-2018
Joined
Oct 3, 2012
Messages
1,653
Reaction score
226
Location
Missouri
I have 2 MK soundboards with a seperate problem for each. The 1st board has very dim sound even with the volume pot turned all the way up, i have replaced the audio amp and still have the same problem, zenomorp suggested changing the caps so I was wondering if anyone knew which ones I should replace. The 2nd board makes very loud static/scratching noise when it boots up but if fades to a very dim static after the game has been on a little while. You can still hear the game sounds in the background but the noise (like if you were driving fast with the window down) is loud at first and then fades to a dull background static. I had a working MK soundboard i put i my dedicated MK cab and it worked fine so I eliminated the volume pot and the speaker in the cab, so I am pretty sure these problems are on the soundboards. I would greatly appreciate any help or advice and thanks zenomorp for your help already!!!
__________________
 
take a picture of each of the boards in question and post it please. I'd start by reseating chips and possibly reflowing header pins and solder legs, but seeing a picture will confirm that all the parts are there.
 
Okay, the board that makes the loud static sound is in my dedicated Mk cab and it worked for months after i bought it, i would get a pic but as you can see it is buried at the moment, all the way in the back left of the row, the soundboard pictured is the one I replaced the audio amp, and after looking at it i remember i did replace about 6 of the caps located around the amp but it still was very dim. hope this info helps and thanks!!
 

Attachments

  • mk soundboards (3).jpg
    mk soundboards (3).jpg
    48.8 KB · Views: 22
  • mk soundboards (2).jpg
    mk soundboards (2).jpg
    59.5 KB · Views: 25
Last edited:
ok everything looks to be in order, check your voltages at the sound board and reflow the headers, you might want to hit all the joints on the board as well.

other than maybe a damaged trace or touching solder leg on the solder side my only other thoughts is another failing chip component which would require a logic probe or looking up the data sheet for most/all of the chips and checking voltage.
 
thanks for the suggestions, i will do what i can, but beyond reflowing some solder and reseating some chips I am getting out of my league. Maybe I will get lucky and that will fix this one, if not I will probably start looking for a couple working sound boards here. Thanks again man!!!!
 
no prob they're fairly easy to find and not that expensive so it's not a huge loss. and you can always put it aside until you have a little more experience repairing things to look at it again.

goodluck!
 
I had an MK sound board with the exact same static issue you are experiencing on yours. I replaced the processor and the static was gone.

Try swapping the processors between the two sound boards to see if that is your issue (the sound CPUs are the longest socketed chip, without a paper label on it).

Brian.
 
Just to be sure, in my picture it would be the long chip located at 12 o'clock next to the sl-1 chip? i believe it is U4. thanks
 
Thanks Brian, i will check it this weekend. I appreciate the help and I will post my results probably saturday.
 
well I swapped the u4 chip to no avail, i ended up swapping all socketed chips while i was in the back of my cab 1 by 1 and had the same result. i guess the problem is in the pcb somewhere and not the ROMS? any ideas?
 
Back
Top Bottom