Treadmill experts in electronics

OK bought this non running treadmill for $2.50 thinking I might do something with it. Pulled the motor on it 240 v DC. DC unit next to the motor with a 4 core control cable going to the user interface control panel, my ? is if I put a pot between which wires to maybe get some speed control, thinking maybe if I get it running make a drum sander or something useful with it, no expert on electronics either but not worried about $2.50.
colours on control cable black yellow red blue.

You would need a rather large pot to run a motor of that size and load.

actually I was thinking maybe if I bypassed the user interface panel and the control cable is 5 core not sure which pair to use, the pot would only be control amps milliamps telling the DC power supply what to do, ahh maybe getting all too hard.

It may not be that simple if its all digital.

All depends on the type of speed controller ( what you have called the power supply) the speed controller is controlled by the user interface panel. What you are trying to do with a pot is provide an analog voltage input proportional to the speed. Some speed controllers will have a 0>10 volt or 0> 5 volt analog voltage input. In that situation you could run a sutuible pot that would vary that analog signal. But I very much doubt a treadmill speed controller with electronic interface uses an analog control signal. The other method is a digital control signal using pulse width modulation. This is where a set voltage say 2.5 volts is switched on and off for a set amount of time several times a second depending on the speed required. So half speed would be on and off identical amounts of time at a set frequency to create a square wave. One for a full second with no break would be full speed etc. This is the most common type of speed controller as it’s just transistors being switched depending on user input and is the most likely way your treadmill motors speed controller input works.
You could build up an Arduino and load some code to convert an analog input ( your pot) to a digital output and interface that to the speed controller.

yes thanks for that, wasnt going to be easy but anyway not worried Nothing ventured nothing gained.

Building an Arduino to run it if it's digital might be more complicated and expensive than needed, probably be worth trying a $5 servo tester first.

If the control panel has a slider or dial to control the treadmill speed then it's probably analog, if it has up-down buttons or multiple speed buttons then it's probably digital. You should be able to trace the wires to the controller.

Search youtube for "treadmill teardown", there are lots of people taking them apart and making power tools etc and you may find something close to the one you have.

What brand/model is it? I have a fair collection of workshop manuals on many treadmills here and a look at the circuit will answer your questions.

If it is non working it may pay to try and work out what is wrong, before pulling it to bits and converting it. if the motor is stuffed no amount of putting potentimeter here and cutting wires there will work !

If it can be made to work in it's original form, why not simply use the original control panel etc.
Ugly but solves a lot of issues