How can I get this treadmill controller running?

[Azalin]

Hello,
My name is Suat. This is my first post on the board.

I have a set of 2HP permanent magnet DC motor, a PWM controller and a console. These are removed from a working treadmill. Everything works when I connect the console to the controller as you see in the photo. I press the "START" button on the console. The relay on the controller clicks, console beeps 3 times and then motor revs.

Only 4 pins to get it working. GND, VCC, REV and SEND.

I want to throw away the console and use the controller and motor in my lathe with variable speed. Just need to wire a potentiometer to the controller but I have no tiny idea how to do it. So my question would be how can I get the controller working with a potentiometer or anything else you can suggest.

Thanks in advance.

Best,
Suat

 

[cowboybob]

Welcome to ETO, Azalin!

It is most likely that the "console" is designed around a μcontroller that is sending the appropriate digital signals that are controlling the PWM portion of the power supply for the motor.

As a result, there is no easy or practical way to replace the console control(s) for the motor with a simple potentiometer. That's not to say it can't be done, but we have no idea of the level of your technical skill/ability. And without a schematic of ALL the electronics for the treadmill, I think it's safe to assume the task would be just about impossible...

What is the component (or whatever) that you have highlighted with the red square?

 

[Azalin]

Hi Bob,

It's a 2 pin connection for the safety magnetic switch. When open everything stops. When closed it all runs. I just put a jumper to close it.

 

[MikeMl]

I recently did exactly what you want to do. I bought a weatherbeaten treadmill from a junk dealer for $5. I was able to discard the console, connect a pot (three wires) to the motor controller board, and make the motor run at any preset speed.

I got useful info from this thread.

 

[dr pepper]

A oscilloscope or logic probe will tell you if the 'send' terminal has serial data transfer when the machine starts/stops or changes speed , if so its a more complex project.

 

[cowboybob]

Hi Bob,

It's a 2 pin connection for the safety magnetic switch. When open everything stops. When closed it all runs. I just put a jumper to close it.

Always a good idea to override safety devices... (previous owner, I assume).

MikeMI makes a good point. Same problem, though, in that a schematic for the motor controller board will be necessary to confirm the pot control mod is doable. Could very well be that the "Send" line is a potentiometer equivalent resistive value from the console.

What's the brand/model number?

 

[Azalin]

What's the brand/model number?

The treadmill was Dynamic 240-M and the model of the controller is AL308C-RZ3.5

I did a wide search on the net for a schematic, diagram or anything related to this controller but no luck.

I tried to connect a 5k pot to REV and SEND but no go. I tried the same with a 5v DC motor PWM driver but it didn't work too.

I found a video which is interesting but I don't know if what he is trying to tell is doable. The story basically is, cut the leg of the transistor (mosfet?) which is the GATE and solder a 5v PWM driver (with a pot of course) and done.

I see this method is my last chance if I could not find a better way. But again, I don't know if this method is going to work.

 

[Azalin]

This is the controller in different color.

 

[cowboybob]

For starters, remove the hold down bar (red arrow)and let us know the part number of the (I assume MOSFET) device (yellow arrow) NO POWER attached to controller board!!:

The videos imply that you can apply a non-PWM'ed DC (via a potentiometer) to the gate of the MOSFET to control the motor. Worth a try.

We'll still need to find a low voltage (5VDC or so) source to feed the pot.

 

[Azalin]

Hi Bob,

5v is no problem.

Please allow me 3 to 4 hours to get home. I already removed the alu cooling shroud. I have a feeling that it was 12n60 but I'm not sure. I'll let you know asap.

 

[cowboybob]

Ok.

... 5v is no problem. ...

The driver voltage (up to 6VDC max) should come from the same board (to avoid ground loops).

 

[Azalin]

Hi again,

Its a G40n60.

I have a 5v adapter in the box for the proximity sensor. Can I not use it?

 

[cowboybob]

The G40n60 is a fast switching device, i.e., really designed for PWM, but... Here's the datasheet: https://www.fairchildsemi.com/datasheets/SG/SGH40N60UFD.pdf

It's probably best to locate a 5-6VDC source on the controller board to avoid any ground loop problems.

Are you comfortable using a VOM (DVM, whatever) on an energized PCB?

 

[Azalin]

What if I desolder the gate then connect it to the pot?

 

[Azalin]

Are you comfortable using a VOM (DVM, whatever) on an energized PCB?

Not really. I plug the cable and run couple steps backwards.

I cut the gate (front view, the left pin if I'm not mistaken) and solder it to the pot. When the pot is full closed I read 160v. Full open I read 140v. Interesting isn't it?

 

[cowboybob]

Whoa. Back up. You're going to hurt yourself. BE CAREUL, Azalin!!! There are LETHAL voltages floating around on this board.
Test the voltage (DC) here:

If it is 6VDC or less, then wire the Pot, using the connections on the corresponding Power Supply connections (Red and Black wires), like this:

The G40N60 appears to handle up to 20VDC on the gate to emitter, but I erring on the side of caution thus far.

 

[Azalin]

I'm fine I'm fine. I didn't die. Yet! But thanks : )

I tested the voltage. It's 13VDC. And I notice that 15v 1W (green marked). Does this mean that the mosfet should get max 15v 1W?

Can you confirm that the GATE is the left leg on the photo?

 

[cowboybob]

Sorry for the delay. Took a nap...

... I tested the voltage. It's 13VDC. And I notice that 15v 1W (green marked). Does this mean that the mosfet should get max 15v 1W? ...

Not sure what that's referencing. This IGBT is rated at 600VDC at 40A (PWM). And it saturates (fully conducts) at around 6VDC, according to the datasheet.

In use, don't forget to reattach the heat shield.

 

[Azalin]

umm, OK! So I what should I try next?

 

[cowboybob]

Try hooking up the pot as I noted in post #16.