NBA Jam Sound issue

TheBatman

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I have been having alot of issues with the sound for my NBA Jam TE lately. The first thing to go wrong was the original volume pot, it turned itself all the way up and would not go down. So I got a new volume pot from radioshack, and my dumbass just grabs one out of the section that says 50k ohm potentiometers, not reading the actual box that says 10k ohm on it. So i get home and plug in the new volume pot, it works for one quick game of jam then sound goes again. This is when I realized I got the wrong pot. So i go back and get a 50k ohm pot but cannot find one that is made for audio/volume only a "linear pot", whatever that is. Get home hook it all up and still just a very faint sound. So my question is, is it that I still have the wrong pot or did I blow a fuse with the 10k ohm pot or did i totally screw up the soundboard?
 
in my limited knowledge back in the day, I've hooked a 5k pot up to my MK1 sound board (which is the same as NBA Jam's) and of course it sounded like it was playing full blast, but it never fried anything.

I bought a couple of the proper replacement pots at Radio Shack before, I lost them at work though lol. I would say check that you're wiring it up properly, how that is, I can't really tell. extremely rusty with pots and stuff.
 
The orginal problem is that it would turn the sound all the way up by itself?
I would be lookig at not at the pot but the ribbon cable between the main board and sound board. Out of the few NBA jam boards I have work on that one cable seems to cause static and volume control issues.
 
i got a bunch of extra ribbon cables if needed :D

very odd that the game volume would slowly increase to 100% (blasting). almost makes me wonder if you got a bad pot. check it with a meter, also check your wiring as mecha stated and make sure that if you have another volume pot in the cab (by the coin door) that it's not causing any added problems.

i doubt you caused any issues with using the wrong volume pot.
 
it wouldn't slowly increase its way to full blast it was just if the pot was plugged in then it was blasting if it was unplugged then there is just very faint sound. When i plugged in the 10k ohm it worked for about 30 minutes, I even turned it up and down to make sure it worked and then I went upstairs and came back down and the sound was gone once again. Now I have a 50k ohm Pot but it doesnt work either but it is a Linear Pot rather than an audio pot, whats the difference?
 
was it in attract mode when the sound was missing? because the sound on my TE goes out after a lil bit of being in attract. but comes back once i coin up pretty sure this is normal as my regular NBA Jam did the same.

"The general rule of thumb is that audio taper is used for volume and anything approximating the volume-like function, where linear is used whenever knowing the "middle" of something is important. As you might expect, linear pots are used for things like blend/mix/balance controls, as well as for EQ controls where identifying exactly where you are either boosting or cutting is important."

Basicly according to that it doesn't really matter, the audio pot is just a lil smoother of an increase/decrease of resistance as demonstrated by this pic (since it's a pic it must be true and therefor "the pic is god")

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i can't remember is there a volume adjustment in the CMOS test menu? (humor me, and check where that's set at) i'm to lazy to get up and hook up my TE to check right now :D.
 
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Have you tried wiggling the ribbon cable?
Audio and linear pots. Both provide resistance. They should both work.

I would be looking for a loose wire issue..
 
my other thought was that maybe the amp / sound board is overheating for some reason and cutting out? check the cmos, check your wiring, feel the sound board after it's been on for atleast 10 minutes for overheating (warm is fine burning hot is not). is the metal heatsink still attached (i'm sure it is).

Snap a pic for us if you could :D
 
i can't remember is there a volume adjustment in the CMOS test menu? (humor me, and check where that's set at) i'm to lazy to get up and hook up my TE to check right now :D.

Just went to the garage to fire up the NBA TE there are no volume adjustments in the cmos test menu. No good deed goes unpunished, neighbor kids are now playing NBA Jam.
Laughs
 
I cannot snap a pic right now but i will get one up asap. It plays sound just very faintly, thats why i think its a problem with the pot, currently there is no pot and the wires are just loose and i still get a little bit of sound.
 
if the pot ever "walks" and changes on its own, then it's probably no good. you can try turning the knob back and forth all the way a few times to wipe it, but if it's still acting up after that then the pot is garbage.

I've gotten 50k replacements at Radio Shack very cheap, surprisingly.
 
The 10K ohm pot worked fine for one game, then after that I cannot get a 50k ohm pot to work. This is why I though it might be a soundboard issue. There is currently no pot connected but I am getting sound it is just at its lowest volume.
 
with no volume pot hooked up to the sound board you shouldn't be getting any sound at all.
 
Thats what I thought, but I am getting sound with no volume pot. What could possibly be the issue?
 
this is the only picture that i took that it is allowing me to upload. For all the others it keeps saying upload failed. this shows the two wires that go to the volume pot(orange and green) and there are a two other wires there that were loose when i got the machine and i haven't figured out where they go...Im pretty sure they have nothing to do with the sound though.
 

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lets see the sound board connection also.

you have to resize your pics smaller to be equal or less than the site restriction.

or

you can upload your files to flickr/photobucket/ect.. and then include a link in your post.
 
got a few more pictures. I noticed that one of the red lights on the main board is out. Could this be an indicator of the problem?
 

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looks like your ribbon cable is backwards on the sound card side of the cable. tough to tell from your pics. the side of the cable with the red trace should be on pin 1 of both boards.

alpha-tron could be the big winner on this one :D

it should look like this:

soundboardwiring.jpg
 
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I been thinking why you have sound when you should not have sound at all.
Some where your your board is reading resistance when it should not be.
Resistance can come from bad cables. I just fixed a friends NBA JAM. It had a Crystal issue and a static noise issues that went away when the ribbon cable was replaced.

The more I study your cable. I agree both sides are reversed.

The Little gray type ribbon cable system has been with us for many years. In the beginning there was never a problem with ribbon cable but as years went the copper in those gray cables started getting more brittle due to the costs. If you stress the cable the wires would not stay in good contact.

If you look at the ribbon cable there is no stress release connector on top of the cables. There are those who will remove a cable not by grabbing the side of the connector and pulling But pulling the cable itself. Small brittle wires plus no stress relief and pulling the cable out by the wires will cause the ribbon cable to start to fail.

I am NOT accusing you of yanking wires. The damage could have been with the orginal maufacturer or anyone else who been inside the cab or dealt with your board before it ever became yours.

Good luck.
 
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