Mortal Kombat 1 PCB - Interesting - Volume Pot

GTRetro87

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Hey All,

So I was playing MK1 in my cab (usually play it on my supergun), and I've noticed this before but I never thought much of it, or bothered to say anything here about it.

Sound and everything works 100% perfectly, 50k pot and all. The only thing I notice is that when you try to adjust the volume (like graze the knob lightly), the volume gets quieter.. and then gets LOUDER like it bounces up and down and it's hard to tell which way to turn the knob to make it quieter. Like the volume creeps up

One thing I must mention, when I bought it from a KLOV member, it was received with the volume pot/cables and sound board cables all wrapped and tied up cleanly. I'll show a pic soon. Maybe it's ok that way, but I've seen this board on google with the volume pot mounted onto a bracket on the sound board

You guys think there's possibly "crosstalk" between the soundboard power cables and the volume pot cables that is causing this to happen when trying to adjust the volume (like when car speaker wires touch the power line and you hear the alternator wine)?

Or is this a natural thing the MK1 boards do?
 
it was a crappy setup to begin with. the caps on the sound board also kind of throw it off too. lucky for you Broodwich carries cap kits and sound pots for those. ;)
 
Have you tried cleaning/lubing the pot? They make potentiometer cleaner, it comes in a spray can. One brand is called Deoxit, if you still have a radio shack, they carry it. These old pots are open to the elements and the spring inside will rust or get dirty on the surface. The cleaner usually fixes it right up. Just spray it in the opening and turn the pot back and fourth completely for a few mins and it will be good to go.
 
Yeah, what Channel said. When the pots sit on one position for a long time, corrosion and dirt can accumulate on the contacts internally. You need to 'wipe' the pot. Turn it all the way up and down really quick a bunch of times to get all the contamination off the contacts. Give that a try.
 
Yea there are definitely a few radioshacks by me, one right up the block from my apartment. I'll pick up that spray and clean the pot.

I find that interesting with the MK2 being digital, I mean I know about the test menu but I'm surprised the sound board is different
 
Mortal Kombat 2 was their first game with the DCS sound system. unlike the previous sound hardware which was a combination of digitization and synthesizer, the DCS effectively plays samples instead. they could studio record music and just store that data in roms vs. making sequenced FM and being limited with what they could do with speech. just envision it playing a bunch of mp3s for music or sound effects, cause it's compressed data files.

it's all controlled by a single processor vs. several subcomponents. it was much more advanced. that's why the volume is digitally controlled. the DCS hardware actually went through several revisions; they eventually got stereo output from it in the late 90s games.
 
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