I plan to take the guts out of one of these, and install an RF transmitter and Arduino micro in their place.
Taking the guts out went well.
However, this has a slider potentiometer, which is mounted to the board and then the board is riveted to the front casing in a way that won't let me see the model number of the pot without tearing it up.
Is there an easy way to figure out the potentiometers value and pin out? It has four pins.
If you have an ohm-meter you can measure the max resistance across the potentiometer.
This will require you to probe around until you find the combination of two pins that yield the highest
resistance.
Once you have found that, you can probe to find the wiper pin that will change value as you move the
slider.
I plan to take the guts out of one of these, and install an RF transmitter and Arduino micro in their place.
Taking the guts out went well.
However, this has a slider potentiometer, which is mounted to the board and then the board is riveted to the front casing in a way that won't let me see the model number of the pot without tearing it up.
Is there an easy way to figure out the potentiometers value and pin out? It has four pins.
Measuring a pot value in circuit can be a problem because the ohm meter voltage can bias diode junctions in the circuit and cause false readings.
So, try this: First, draw a picture of the pot (where the pins are) and then set the pot about 1/3 of it's travel (doesn't matter which way).
Measure the resistance between all combinations of pins and write down the readings on the drawing. Then do the same with the ohm meter in the opposite polarity and see if there are any different readings. If you get any different values, keep the HIGHER of the two because a biased diode junction will always make the reading lower.
With all the values on the drawing, it should be easy to see which pin does what. If you see something like "3500 ohms" on one set of pins and "6500 ohms" on another set and "10000" somewhere else, it will be obvious what you have.
Lastly, when you think you know which pin is which, move the slider and see if it changes as you expect it to.
Easy.
Thanks for your responses guys, I was able to take another look at this this afternoon.
I have taken a fiew pictures which show the readings a get in ohms....
This is if the slider is in the "up" position..
http://s10.postimg.org/6bo2d22rb/image.png
and if the slider is in the "down" position...
http://s10.postimg.org/dsx9s9saf/image.png
these are pictures of the board, with the pen showing "pin 1".
http://s3.postimg.org/3q4wcg9hv/image.jpg
http://s3.postimg.org/4edqve87n/image.jpg
I think that GND and VCC are pins 2 and 4 and that the pot read pin are pins 1 or 3. But i'm not sure. Also, i only get 2 ohms from my meter, is this a 2 ohm potentiometer? Or is something else happening? I don't have any voltage going to the poteniomenter during the test.
Hi you need to set your DMM ohms range higher.
Thats is why you have pins 1 and 2 with infinity one way and 1.2ohms the other.
Keep increasing the range of your DMM until the infinity reading configuration changes to a value.
Then redo the test on that ohms range.
I assume your DMM is not auto ranging.
Tom..... 
I'm pretty sure it is auto ranging, as I also use the meter to test heating elements in hot water heaters and they read 35
I think it reads it I thousands though, so that might be 2.2 thousand ohms.
This is the meter
Hi,
Your DMM is an electricians DMM, any resistance over 4000ohms will be requarded as open circuit.
Tom....
Well, I am an electrician....
So, there is no way of figuring this out without buying a more accurate meter?
For under $50, which meter do you recommend?
I searched for an electronics meter on Amazon, but nothing particularly useful popped up.
Link does not work.
Search for "DMM"
Get a MANUAL meter. Not a bloody annoying autoranging one.
Leo..
It's not totally necesssary to get a manual meter. Autoranging does work for simple measurements like this. It will be worth your time to read the manual and work out how to get it out of auto mode.
Cheap pocket-size meters can be had for $12 or so. That's what I use most of the time, even though I keep mine on top of an 'accurate' meter which is too heavy to be lifted off the bench.
Hi,
I would say that pins 1 and 3 are connected to the wiper.
pin 2 is one end of the pot.
pin 4 is the other end.
Its value is >4K.
See attachment
Tom.....
