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Mortal Kombat 1 with partial sound

Posted: March 14th, 2017, 12:53 am
by Tardisdad11
Hi I have a mortal kombat 1 cab where I had to install a volume pot to turn it up but am still only getting music during matches uppercuts background music etc but am missing sounds any ideas? Sorry very new to this.

Re: Mortal Kombat 1 with partial sound

Posted: March 14th, 2017, 11:08 am
by Asayuki
From your few words it sounds like the game board has an issue in the audio section.

Re: Mortal Kombat 1 with partial sound

Posted: March 14th, 2017, 3:44 pm
by neocps1
go to test mode and in the test mode you will be able to test the sound board.
Basically, The sound board will make a number of sounds which correspond to
a status code (1 'dong' : ok, and so on).

This will help you find whats wrong

Re: Mortal Kombat 1 with partial sound

Posted: March 14th, 2017, 5:40 pm
by Tardisdad11
Thanks I did that initially and it says everything is fine it's so weird i just don't get sounds like names and finish him and some punches and kicks and also no music on the demo/start screen

Re: Mortal Kombat 1 with partial sound

Posted: March 16th, 2017, 9:38 am
by neocps1
Do you get bad sounds on some occasions ? I mean sound which should be happen in a particular situation ?

Re: Mortal Kombat 1 with partial sound

Posted: March 16th, 2017, 12:22 pm
by crunchywasp
Turn cab off

Remove PCB from JAMMA harness

Put PCB in bin

:whoopsie:

Re: Mortal Kombat 1 with partial sound

Posted: March 16th, 2017, 10:28 pm
by leonardoliveira
Don't williams hardware require -5v be present for the sound to work properly?

Re: Mortal Kombat 1 with partial sound

Posted: March 16th, 2017, 10:40 pm
by crunchywasp
Good point 8-)

I'm pretty sure MK needs -5v, but I thought there was no sound at all without it?

Re: Mortal Kombat 1 with partial sound

Posted: March 16th, 2017, 10:53 pm
by Asayuki
crunchywasp wrote:Good point 8-)

I'm pretty sure MK needs -5v, but I thought there was no sound at all without it?


Taito system L for example only uses -5V for the digital sound section, so yes there are boards where a missing -5V causes quite some headaches.
Yet from my understanding this issue happened all of a sudden and it was working before. Am I wrong?

Re: Mortal Kombat 1 with partial sound

Posted: March 18th, 2017, 6:01 am
by leonardoliveira
crunchywasp wrote:Good point 8-)

I'm pretty sure MK needs -5v, but I thought there was no sound at all without it?


I believe it's used for the op amps on the analog part. Without it I believe you get pops and weird distortion instead of normal sound.

Re: Mortal Kombat 1 with partial sound

Posted: March 18th, 2017, 8:53 am
by crunchywasp
Ahh, grand, thanks. I stand korrected.

Re: Mortal Kombat 1 with partial sound

Posted: March 18th, 2017, 10:10 pm
by Tardisdad11
Sorry guys I don't get notifications saying anyone has replied and no distorted sounds it's almost like I'm running a stereo on just one speaker I get only half sound like the balance is turned completely to one side....

Re: Mortal Kombat 1 with partial sound

Posted: March 19th, 2017, 11:50 pm
by leonardoliveira
It's possible that you have one or two faulty op amps. The FM sound synth works but you get no voices? Could also be the eprom which stores the sound samples for the adpcm sampler circuit.

Re: Mortal Kombat 1 with partial sound

Posted: March 21st, 2017, 12:37 am
by Tardisdad11
my diagnostic still comes up clear on the sound board does that matter?

Re: Mortal Kombat 1 with partial sound

Posted: March 21st, 2017, 3:43 am
by leonardoliveira
I think the newer William systems with the SHARC DSP (Wolf board with MK III for example) can but the early ones with the OKI ADPCM chip can't. Your game has a OKI M6295 ADPCM sampler for voices at the sound board. Two EPROMs connect to it and hold the wave data. The third rom holds the program for the MC6809 CPU at the sound board.