Volume pot issue

[mh12]

I'd really like to take care of the volume issue on my cab (have to open the front door to adjust it, unless i'm using shifted keys to adjust it in MAME... and I'd rather leave the software volume alone)

here is the cab's volume pot:



I assume I could de-solder the 6 points and extend the pot with some wires to stick out somewhere (correct?), but the thing is that the pot is very sensitive. If I could find a pot with a greater range of motion, would it work with this? It looks generic enough.  Or anyone have a better idea?

[DaOld Man]

You could leave that pot alone, turn it to what you want max volume to be, then add a new pot between the PC and the amp. The new pot would basically go in the wire that runs from your amp to your PC.
I did this on the two jukeboxes I built, works pretty good.

[mh12]

Strip my RCA > 3.5mm cable, eh... that would be great if I could pull it off. How's it done? Is there a guide around? Thanks for replying

[MK3FAN]

Strip my RCA > 3.5mm cable, eh... that would be great if I could pull it off. How's it done? Is there a guide around? Thanks for replying

If you know the range (ie 10K ohm, 20K ohm), you could simply remove it, run longer wires, re-solder it and voila! That would be my suggestion.

[MK3FAN]

Disregard this reply.

[Nacimroc]

You could leave that pot alone, turn it to what you want max volume to be, then add a new pot between the PC and the amp. The new pot would basically go in the wire that runs from your amp to your PC.
I did this on the two jukeboxes I built, works pretty good.

Which wire would you connect to the pot ? or all wires ? Im using a 3.5mm to phono lead so I'm presuming the left and right channel cables have 2 wires each!

[DaOld Man]

What I did was buy a PC audio extension cord from radio shack and hacked it into a pot.
This way if the amp ever goes bad, or I decide to upgrade it's a very simple matter, just unplug, then plug new back in.
I didnt get into great detail in my jukebox thread, but it might give you an idea. If you need more help, Id be glad to help out.
Here is my jukebox thread, the part about the pot is on the very last page.

http://forum.arcadecontrols.com/index.php?topic=85953.120

[Nacimroc]

Thats perfect! thanks!

Nice juke project btw!

[DaOld Man]

Thank you!
It was one of the several Mountain jukebox copies on this site. Some (most) did a better job than I, but who I built it for likes it. And after 1 year, it is still working great.

[Zebidee]

Check out a couple of web pages I wrote a while ago explaining how to put a volume pot into your cab. Includes pics & hints on how to mount the pot!

Volume pot wiring & mounting

You can also add a headphone jack pretty easily, which is a great addition to every cab

Cheers, Zeb

[Breaker]

Hi all,

I also used this technique to extend the volume control on my CAB and the only caution I would add is to route the wiring
away from your control panel wiring. I don't know if my situation was unique, but I ended up with a high pitched whine in my
speakers after extending the volume control. It took me a long time to realize it, but I had run my volume control wires in the
same wiring conduit as my control panel wires, and it was causing the whine. I assumed it was interference from the control
panel wires because once I moved the speaker wires to the other side of the CAB all was good.

Breaker.

[mh12]

thanks guys.
i took daoldman's advice and got another pot the same as the one attached to a board in my cab, and soldered it up, in-line. found a little knob for it too. while i was at it i picked up a splitter and a short headphone extension cable to make a headphone port (so speakers and headphones can be on at the same time... or just turn down the volume pot to make it headphones only).

i put the volume knob where the coin mech door lock was, and the headphone extension (as well as 2 USB extensions that i use for pads for 4 player games sometimes) are all sitting in the P1 coin return (only the second slot has an actual coin mech). as soon as i find a glue that will properly bind these things to my candy cab, i'll put up some shots (it's looking pretty crap right now). i like setting it up this way since when it comes to the control panel and up, there's nothing to distinguish it from a cab in an arcade..... and it keeps me from having to drill anything for a volume knob 

[Bender]

Old thread but good info...

I read that ideally  the pot goes between the output source and the amp
can you but a pot between the amp and the speakers?

[Zebidee]

Not recommended. The pot will work much better between source & amp

A pot between amp & speakers is not good practice - it would need to be higher rated for the more powerful signal. You'd be 'wasting' a lot more power (ie power used in amplification), as you'd be shunting much of it to ground. Also, you'd probably get 'impedance' interference as the amplifier expects a certiain level of impedence from the speakers - typically just 4/8/16 ohms, a lot less than the 10,000 ohms or more that you would find in even a small pot.

[BobA]

+1 for Zebidee  Not recommended. The pot will work much better between source & amp

[Bender]

Thanks for the heads up!

OK, full disclosure here
I'm using a 60 in 1 Jamma board that acts as the amp too. It has a mini pot on it to control volume and I want to put a volume knob on the cab

What is the best way to do this?

It looks like there are 3 pins to this pot. It is mono.
So could I just run some wires from the pins to a pot on the cab?
How do I test to see what pin goes to what on the new pot?

[DaOld Man]

Best case scenario would be to de-solder that pot and solder in jumper wires to your new pot, but since Im sure you dont want to take a chance of screwing up that board, you can try just connecting the new pot to those solder pads.
Then you can leave the old pot turned to midway position.

To find out what connections are what, use an ohm meter (DVM is best), turn old pot all the way down (silent).
measure between two of the solder pads. The two reading the lowest resistance (very close to zero) will be the ground and the wiper.
Now turn the pot all the way up (loud). The two measuring the lowest resistance will be the wiper and the input.
By process of elimination, pick out the wiper. That will be center tap on the new pot.
If the new pot acts reverse (up is silent, down is loud), just swap the two outside taps on the new pot.
Your modification will work a lot better if you just remove the old pot though.

[Zebidee]

Despite my former advice, most game PCBs are designed to go into cabs, most cabs are fitted with volume pots and the PCB amplifiers are designed for encountering variable situations sooooo ....... maybe you just have a look at what pots they use in other cabs and try that first.  We don't want you to hack up your PCB unnecessarily. I'll have a look at some typical pot values for you tonight (off to work in a minute).

[Encryptor]

Check out this thread from the Oscar Mirror Site.

http://mirrors.arcadecontrols.com/OscarControls/volume/index.shtml

Encryptor

[Bender]

Thanks so much everyone, keep the info coming!

Right now I think I'll try soldering in to the existing pot and see how that works, then I'll move on to desoldering the old pot if necessary

I'll post back and let you know how it went

[DaOld Man]

Good luck Bender. You might want to get some 2 conductor shielded cable to run between the board and the new pot.
The shield will attach to the grounded pad on the board, and it will be the third conductor. It will prevent any interference (noise) from getting into the wires.
If the pot is very far from the board, it might be a necessity to run shielded wires.

[Zebidee]

Look, leave that poor 60-in-1 PCB alone. There is an better way.

I've got a pot here in front of me from an arcade cab with relatively good speakers (for an old cab - it came out of a  Mortal Kombat cab), designed for use with "normal PCBs" (MK have a special secondary sound board), with modest-good volume amps built in. It is only a 50 ohm pot (NOT 50K or 50 kilo-ohm) pot. I'm not sure of the wattage rating, but it says on the pot: "G2 50R AW 1RH". The cab only had one speaker (no more than about 8 watts) and a little subwoofer.

I'm been running a 48-in-1 in a cab with a similar volume control myself. It is in a staff work amenities room and is on everyday. Works wonderfully.

Soooo .... in this PCB case, I recommend that you go with something like that before hacking your board.

[Bender]

Look, leave that poor 60-in-1 PCB alone. There is an better way.

I've got a pot here in front of me from an arcade cab with relatively good speakers (for an old cab - it came out of a  Mortal Kombat cab), designed for use with "normal PCBs" (MK have a special secondary sound board), with modest-good volume amps built in. It is only a 50 ohm pot (NOT 50K or 50 kilo-ohm) pot. I'm not sure of the wattage rating, but it says on the pot: "G2 50R AW 1RH". The cab only had one speaker (no more than about 8 watts) and a little subwoofer.

I'm been running a 48-in-1 in a cab with a similar volume control myself. It is in a staff work amenities room and is on everyday. Works wonderfully.

Soooo .... in this PCB case, I recommend that you go with something like that before hacking your board.

Sorry to be dense but...  do mean just bite the bullet and add powered speakers?

[Zebidee]

no, just suggesting that you buy a 50 ohm pot similar to the one I described. Ask about it at your local Radio Shack / Jaycar / Dick Smith or other hobby electronics store.