Mortal Kombat 1 sound board issues.

r3m

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Well I have a MK1 sound board that is a little screwy. Random Goro sounds, falling in the pit scream, sounds of sonya when I choose raiden, etc. I've had it for a while but just decided to go ahead and try to fix it. I replaced about 12 capacitors that tested bad and I was checking a row of resistors and I'm getting crazy readings. I'm not sure they are even resistors. They look exactly like resistors but the body is light green and not beige like a regular resistor. When I check the ohm on the 11 what I think are resistors I get 8 out of 11 of them that says pretty much 90k ohm and the other 3 I get no reading at all. The color bands don't make sense on them either. Brown, black, brown, gold, white. I have replaced white as possibly being silver and get nowhere near what I'm reading on the meter. On the sound PCB these are c35, c36, c37, c38, c39, c40, c41, c42, that get 90K ohm readings. The 3 that don't have a reading at all are c43, c44, & c45. If they are resistors why don't they have an R in front of the number like the rest of the resistors? Also should I at least get a reading on the 3 that shows nothing?

I'm sorry if it's confusing but it's confusing me so bad I don't even know how to explain it.

Thanks!
 
if they have C labels then I'm going to say they're probably little capacitors.

seems like people are having a lot of problems with MK1 sound boards now.

as far as the random sounds, did you ever do a Sound Board Test in the test mode to see if any of the roms show bad? it won't be like the CPU board test where it shows green or red, it'll make the power on beep sound a number of times and however many beeps it is will correspond with the legend at the bottom for which rom is bad.

which I would pop the roms out and inspect the legs for any corrosion. if there is, sandpaper works wonders on cleaning up the legs.

maybe it's not a hardware issue at all, it might just be the roms.

the caps would probably cause you to have no amplification or the hardware to not function right if anything, but I've been pretty lucky with sound boards.. haven't had such a problem yet lol
 
Well I have taken out each rom and verified the checksum and cleaned the legs with a pencil eraser and they all show green during boot up. The only eproms I can't verify are the little removable ones that are at U18 and U28. I don't see scratches on the sound board and no legs touching. The sound would go loud and then really low randomly which after replacing the caps it doesn't do anymore. I have never seen caps with bands on them and looks exactly like a resistor. I put them on my capanalyzer 88-A and it doesn't even recognize them as capacitors. That was the 2nd thing I thought since it had a C in front of the numbers.

I will go into the test menu and see what beeps etc I get.

Btw I have tested this sound board on another working MK1 pcb and same sound issues. I also want to add the heat sync gets pretty warm but I don't know what the normal feeling of the heat sync should be as this is my only sound board.

Thanks
 
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Just to make a correction. I have NOT checked the data on the sound PCB eproms as I don't see them in the roms I have. u14, u4 u18, u28 are the ones I would need to check if I had the roms. I know it's against the rules asking for them but I have no way of checking them without them.

Edit: Found u3, u12, u13. Can't find the other sound roms. u3, u12, and u13 test fine in my programmer. re-cleaned the legs on the removable eproms.

Let the game run for about 3 minutes and that IC on the heat sync is getting really hot. Can't hold my finger on it for more than 2 seconds.
I can hear some squealing and popping noises under the music and sound effects.
 
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have you checked the solder legs on the solder side for touching pins? I recently picked up a mk1 where the soundboard would play random sounds when certain ones were played. it was caused by touching legs on the solder side.

let me know.

squeeling and popping is never a good sign tho (i've got 1-2 of these boards that do that right now).
 
Some of those sound like fun random goro and pit screams?

I bet Raiden's voice on Sonya is funny.

I hope you get it fixed though.
 
I'm having very similar issues... I'm working on my MK 1 cab now. Here is a video of some of the sounds... I am also getting the random Pit falling scream... And the announcer voice says fight, but not finish him / fatality...

Here is the video:

 
I'm having very similar issues... I'm working on my MK 1 cab now. Here is a video of some of the sounds... I am also getting the random Pit falling scream... And the announcer voice says fight, but not finish him / fatality...

Here is the video:


Exactly what I got!
 
Let me know how the sound rom test goes for you... I have the monitor out of the cab right now and it will probably be a week or two before I can run a sound rom test...

Its annoying when things don't work right!
 
have you checked the solder legs on the solder side for touching pins? I recently picked up a mk1 where the soundboard would play random sounds when certain ones were played. it was caused by touching legs on the solder side.

let me know.

squeeling and popping is never a good sign tho (i've got 1-2 of these boards that do that right now).
I've already checked the legs and none of them are touching. I'm going to hit a couple more joints with some solder in a little. I did find 1 scratch going along a trace and not across and has full continuity. I did nothing to it.
Some of those sound like fun random goro and pit screams?

I bet Raiden's voice on Sonya is funny.

I hope you get it fixed though.
Ya it was cool at first but it get annoying really quick especially if it's the only sound board I have. I even get random "OH NO OH NO!". Not sure where in the game that is. Thanks, I hope so too.

Let me know how the sound rom test goes for you... I have the monitor out of the cab right now and it will probably be a week or two before I can run a sound rom test...

Its annoying when things don't work right!
I checked the sound roms last night with my eprom reader. At least the 3 I mentioned that come with the Mame roms .zip and they test fine.


On a side note I did find 2 resistors that are out of tolerance. 120K ohm and can't remember what the other is. I know I don't have 120K ohm resistors though. Checked 5 TV pcb's and not a single 1! I wish I knew how to test those green things that look like resistors as I get no reading at all from 3 of them unlike the other 8. Can you test c43, c44, & c45 with your meter on ohms to see if you get no reading as well please?
 
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Yea, I'll be working with it tonight as well... I may plug it into one of my other cabs as well to run the sound check...

On a side note, I see you are close by!

Ya I haven't tried the sound check that was mentioned earlier as I've been testing it in my KI cab that is already pulled out. Looks like I'll have to pull out the MK cab. Ya not too far away huh? About 2 hour drive.
Thanks
 
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I'm having very similar issues... I'm working on my MK 1 cab now. Here is a video of some of the sounds... I am also getting the random Pit falling scream... And the announcer voice says fight, but not finish him / fatality...

Here is the video:


that's pretty much what mine was doing as well when it had solder legs touching. basically during the attract mode when KANO would come up and it would say his name it would also say "RaidenSubzeroScorpionSonia" ect....


R3M have you tried a different Ribbon cable as well as checked your voltages? didn't see that mentioned like the solder legs
 
Ya sometimes when Kano comes up I hear fatality or whatever else it likes to spit out. I have checked the voltages etc. I have it in my KI machine which is a brand new PS and also tried in MK1 cab adjusting voltages etc. I did notice I missed a bad cap which I'm going to replace which I doubt it will help but I already did all the others so why not. I haven't tried another ribbon cable as I don't have 1 and have no money. I have old computer parts but this looks like no ribbon cable I've seen in a old computer before. =(
 
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Ok replaced that cap, touched up some solder joints. Only things I know to do as of right now is to switch the ribbon cable and replace those 2 resistors that are out of tolerance. I haven't even checked all of the resistors yet. I have to think of a system so I don't go over the same ones I already checked. There is also a couple transistors I see that can be checked. Going to see what happens now.
 
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Well I did everything I said in the previous post and no change at all. I'm starting to pull out what hair I have left. It's really starting to get to me.
 
Well I did everything I said in the previous post and no change at all. I'm starting to pull out what hair I have left. It's really starting to get to me.

damn even swapping out the resistors?

iirc you can use a laptop ide (44pin) ribbon cable just to test and see if the cable is the issue. I haven't tried this but it should work (as long as there's no twist in the cable, like some ide cables do). thinking about this a lil more and a floppy cable might be better.
 
No I haven't changed the resistors yet. I want to see if there are any more that are bad and head over to radioshack to see if they have them. If they don't I'll have to order them. I still have to check those transistors as well. I was thinking about a floppy cable as well not sure how I would use that because the MK board only has I think 25 pins. I'll have to see if I have any computer cables. I guess I'll post what I do next. I gotta find my box of misc computer parts.
 
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