NBA JAM sound too loud

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Hello all

I have a working NBA JAM v3.1 board set that passes all checks (main +
sound board).

My problem is that it is far too loud, so much so I have resorted to
unpluging the speaker from the cabinet.

There is a large metal pot attached via two wires to pins 2 and 4 of P5
on the sound board set that I assume is a volume control, however
adjusting it does not work at all.

Is this a common problem, and how would I go about fixing the problem?

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

I looked through all available options in the test mode and could not
find anything related to the volume.

Thanks anyway.

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Probably a bad volume pot. The big metal pot coming off the sound board is
how you adjust the volume. NBA Jam did not have volume control in the test
menus. Get a new pot and you should be fine.

Brian

"Evan Clarke" <evanclarke@fastmail.fm> wrote in message
news:1117887866.545472.285990@o13g2000cwo.googlegroups.com...
> Hello all
>
> I have a working NBA JAM v3.1 board set that passes all checks (main +
> sound board).
>
> My problem is that it is far too loud, so much so I have resorted to
> unpluging the speaker from the cabinet.
>
> There is a large metal pot attached via two wires to pins 2 and 4 of P5
> on the sound board set that I assume is a volume control, however
> adjusting it does not work at all.
>
> Is this a common problem, and how would I go about fixing the problem?
>
>

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

If it's anything like MK1, then you need to go into test mode and adjust the
volume there as well.

Rob


"Evan Clarke" <evanclarke@fastmail.fm> wrote in message
news:1117887866.545472.285990@o13g2000cwo.googlegroups.com...
> Hello all
>
> I have a working NBA JAM v3.1 board set that passes all checks (main +
> sound board).
>
> My problem is that it is far too loud, so much so I have resorted to
> unpluging the speaker from the cabinet.
>
> There is a large metal pot attached via two wires to pins 2 and 4 of P5
> on the sound board set that I assume is a volume control, however
> adjusting it does not work at all.
>
> Is this a common problem, and how would I go about fixing the problem?
>

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Doesn't seem to be the volume pot.

Disconnected it and hooked up my multimeter, it read from 0-45K, within
what the pot is (50k). Tried a 100K and 500K pot to see if it made any
difference, but it didn't.

Then I just tried without the pot at all, the wires either connected to
each other or not. The difference was barely noticable.

For the time being I have put the pot inline with the speaker itself to
control the volume, but this is a bit of a hack, I would rather have
the sound board working correctly.

Any ideas?

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Make sure the pot is grounded. I can't remember if this pcb used an
attenuator ic to control audio vol or if they were just shunting the
audio signal to gnd. Either way, sounds like the leg of the pot that
should be at groung potential is not there. Check the cable first if
there is one, then at the board.

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

I am afraid that some of what you said went over my head, so I will
tell you what I know and what I think I understand, and if you could
fill in the gaps with some sort of baby noises and rattle shakes I
might be able to work it out.

The cable running to the pot has only two wires, both connected to the
pot and the board (pins 2 and 4 of P5) through a plastic plug. There
is also a pin 1 (but no 3) on P5, but nothing is hooked up to it.
There is also a spare pin on the pot - should I connect them?

The pot mounting bracket is metal as well, should that be earthed
somehow instead of just screwed into wood?

Thanks for your help.

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Evan Clarke wrote:
> The pot mounting bracket is metal as well, should that be earthed
> somehow instead of just screwed into wood?

No. In fact, if you don't have a pot, you can just stick a resistor
between the two wires and use that instead (I did that for awhile).

I'd suspect that your pot is the problem here.

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Thanks for the guess but I have already tested the pot using a
multimeter and it was within spec (0-~45K). To make sure I also used a
100k and 500K pots and they made no difference.

To make doubly sure I also removed the pot completely and just had the
wires touching and not touching, with barely any difference noted.

Please keep the ideas comming.