JAMMA (sound) via SCART to TV

[MrSandman]

Hi!

So far, I built 3 JAMMA compatible MAK/Superguns myself (make holes in box, put connectors in holes, attach wires to connectors, put wires in box, close box) for my MVS, HNG4, CPS2 and other PCBs and had no problems at all so far .

However, I have read several times, that the voltage output on some PCBs for the sound is higher than a standard TV can take ; according to the Wikipedia SCART page the output is typically around +0,5V.

Does anyone know if a Mortal Kombat 1 and 3 or original Street Fighter 2 board works fine on TV or are any adjustments needed (AFAIK the MK1/3 and SF2 board need -5V for the sound)?

Thank you for your help
-MrSandman

[Rossyra]

Jamma should be run through a line level converter or you risk blowing the TV sound hardware.

Jamma outputs amped audio

[KmanSweden]

Here's how I did it.. It's in swedish but I think you'll manage to figure it out anyway.

Borrowed the pic from Uncletom over at arkadtorget.se.

[MrSandman]

Hi guys!

Thanks, KmanSweden for the pic. Figured it out, but the way I use it is different.

• *I dont use pin 8 at all, only 16 with a resistance of 150
  *Why do you use resistance on the Sync?
  I*'ve put the JAMMA Audio + directly on pin 1&3 and JAMMA Audio - on GND (and seems to work fine).

Do you have pictures of your DIY MAK/Supergun ?

Jamma should be run through a line level converter or you risk blowing the TV sound hardware.

Yup, that is what I've read and ignored so many times.
Is a HiFi component, like a HomeCinema-Surround system adequate?

[dj_johnnyg]

I assume using a 280 ohm for pin16 is because they are using the 12V line. I usually use 5V through a 100 ohm, but it works out roughly the same:

V=IR >>> I=V/R

I= 12/280 = 0.043A
I= 5/100 = 0.05A

I used to set the volume POT on my JAMMA boards to give me an output of 0.4-ish volts, and then hotglue. Failing that, I'd attach a connector to the Audio lines before they hit the AMP section (where possible) and then have an un-amped signal.

Then I got a cab

[KmanSweden]

12 Volt on pin 8 turns the TV channel to AV-chanel automatically, in 4:3-mode, and pin 16 gets something between 1 and 3 Volts to change it to RGB-mode.

EdiT: Movie of it running.. http://www.koskimaki.se/res/MAME/Supergun/MVI_2687.wmv
Picture of it neatly tucked away in itself... I don't think I've used it more than once after building it..

[MrSandman]

I usually use 5V through a 100 ohm, but it works out roughly the same

Yup, use +5V too works just fine.

I used to set the volume POT on my JAMMA boards to give me an output of 0.4-ish volts, and then hotglue

You put glue on the PCB POT?
Do you have any recommendation of what ohm for a POT to use if I want to attach it to the audio wire (PIN 10?) to get a level of ~0,5V?

Thanky for your help

P.S.: Thanks for the formulas; gotta look into that stuff soon

[MrSandman]

12 Volt on pin 8 turns the TV channel to AV-chanel automatically, in 4:3-mode, and pin 16 gets something between 1 and 3 Volts to change it to RGB-mode.

EdiT: Movie of it running.. http://www.koskimaki.se/res/MAME/Supergun/MVI_2687.wmv
Picture of it neatly tucked away in itself... I don't think I've used it more than once after building it..

"Toolbox" great, really original that MAK/Supergun.

Thanks for the pics and vids.
Did you use the occasion to show off you lovely MS1 to me?

Must put a Wanted thread on the forum for this game some time

[KmanSweden]

Glad you liked it.

[MrSandman]

Hi guys,

I think i need some help again (this time with the maths):

V=IR >>> I=V/R

I= 12/280 = 0.043A
I= 5/100 = 0.05A

I assume you got the required 0,04A by: 3V / Z 75Ohm, then you get the required R by 12V / 0,04A (roughly), right?

So, how strong should a Pot be on my Audio Line (JAMMA Audio + -> Pot -> JAMMA Audio -)?

And what exactly does "amped" mean? Higher V oder higher A (or both)? And how much higher?

Thanks