volume pot hardware question (unrelated to atari)

[bomberpunk]

i'm trying to add a volume pot wheel and a headphone jack to an annoyingly loud vintage handheld game.

 

i did one modification already, but i can't fully close the plastic shell because of the thickness of the headphone jack:

so for my next project, i have these two parts:

 

i couldn't get a clearer picture, but the jack has 3 prongs, and the wheel has 2 on one side and 5 in a row on the other side. i'm familiar with the jack but have no clue how this wheel works (as in which prongs do what). i suppose that's on google.

 

my questions are:

(1) how do i mount the wheel since i'm not soldering it to a board? should i just superglue it to the inside plastic shell of the game?

(2) how do i rig this thing so that the game's external speaker still works and gets shorted when something gets plugged into the headphone jack?

 

[+Stephen Moss]

Let's start with the pot, with out looking at a data sheet I cannot imagine why it would have such a connection arrangement unless it has 5 fixed selectable output values (max, min and three in between) as opposed to being constantly variable.

Presumably you are intending to have the edge of the wheel protrude through the case handhelds case so that you can adjust the volume in which case if there is room then using superglue or araldite to attach it to the inside of the case is probably your best option.

 

 

You do not want to short the speaker out, you need to make it open circuit (stop the audio getting to it).

I would expect the front connector of the Jack socket to be the ground (GND/0V) connection, if it as a stereo socket then the other two connections will be left/right in however if it is a mono connector then the then they will probably be a switched in/out.

 

Try to find a manufactures data sheet, hopefully it will show a schematic diagram of the connectors circuit, with 3 connections could show either...

a)

1 straight line (GND) and two ending in a V = Stereo non switched - only way to use with the speaker would be to insert a stereo plug with left/right wired together when not using headphones so that the singnal goes in left and out right (or visa versa) to the speaker.

 

b)

1 straight line (GND) and one ending in a V & the third either not connected or connected to the second = Mono non switched - cannot be use for both headphone & speaker pass through.

 

c)

1 straight line (GND) and one ending in a V & one ending in an arrow (point to the one ending in a V) = Mono switched - connect audio to connection ending in a V and the speaker to the one with the arrow (should be the switched connection).

With the headphones in you should get sound out of them and with the headphones removed the switched connection automatically connects to the signal and audio will come out of the speakers. If you only get sound out of the speaker and none from the headphones then those connections are reversed.

 

If you cannot find the data sheet/connection diagram you could use a multimeter (DVM) to measure the resistance between the other two connections, if it is a switched mono socket (which is what you want) the resistance should be low (>10) with no headphones and infinite with the headphones in, however you still would not know which is the switched connection until you wire it up (see c above re reversed connections)