View Full Version : Problematic Mortal Kombat Sound Effects

12th September 2006, 02:58 PM

I have an MK Machine which has been in storage for about 5 years, when it was put away, everything was working fine.

Upon coming out of storage, turning the machine on caused a while bunch of random glitch noises from the machine.
Slowly but surely it seemed to get better and the sound worked randomly, with a fair bit of static sound in the background.

Now, after a couple of days, the machine is silent, with a harsh humming noise coming from the speakers.
When I run the machine is test mode, all roms diagnose fine.
The Sound Test has the music running fine, but when it attempts to play a sound effect, the machine goes silent, at which point when I scroll back to the music, it remains silent.

Any ideas ?


12th September 2006, 03:37 PM
check your connectors., i'm also thinking the power supply might not be connected properly or may be failing to provide the juice needed for the sound.

12th September 2006, 10:26 PM
I had a similar problem with my Mk it turned out to be the power supply ...

16th September 2006, 12:33 PM
check your connectors., i'm also thinking the power supply might not be connected properly or may be failing to provide the juice needed for the sound.

I have checked all the connections, everything seems fine.
I've also tested the outputs from the PSU, and everything is pumping out the right voltages.
I assume, if there was an issue with the PSU, it would show some form of problem, but it doesn't, there are no major drops in power when music is playing, or the sfx try to play, etc.

I have done more testing and can replicate the issues.
If I go into diagnostic mode, it has "ding" effects as you scroll through the menus. When you choose sound test, it plays music. When I scroll through to the sound effects, it goes silent. At which pont, the music won't start again.
BUT, I then exit that menu and go back to the main menu, and scroll creates the "ding" sounds again. I can then re-enter the sound test menu and the music will work, but sound effects cause it all to go silent again.

Any ideas ?

Arcade King
16th September 2006, 12:52 PM
do you know anybody with another sound board for the pcb? perhaps try swapping boards over then you will know if its a hardware fault or not.

16th September 2006, 07:51 PM
It is the sound board,
Its been a while since I looked at one but last time I looked I remember it was something near the amp.
There is a op amp there which could be the problem, it was special in that it was software programable for volume) and a coil of some type.
It wont be the amp itself and I dont think it was caps either but it wouldnt hurt to check them if you have the right meter, or you could just replace them because they are cheap as chips anyway.

BTW before you get to heavy in it make sure no pins are bent on the back of the PCB and that no corrosion has eaten away at the PCB the basic checks first will save you some time.

16th September 2006, 10:49 PM
Hey Sonny are you in Brissy ? If so i have a spare sound board for a NBA which you can test it with ... I will be down there next week :)

19th September 2006, 08:16 PM
Buzzbox - Nah, I'm in Sydney, but thanks for the offer.
If anyone is in Southern Sydney, I'd love to hear from you :)

Gamedude - I'll have a look and see what I can find out, I personally am not that biggest electronics guru, but I do have friends that are.