Hokey-Pokey treadmill motor

Thread Starter

Kandar

Joined Mar 30, 2020
2
Hi everyone. First id like to say that their is a ton of good information in these forums and it is a great resource.

I have built a 2x72 bench grinder and needed a motor for it and my employer was tossing out a Landice treadmill. So i grabbed the motor and power supply off of it which still worked.

The motor is 4500rpm 130v 4hp 30a continuous pmdc motor. I don't believe it is one of the junky ones.20200207_110655.jpg

The power supply is a Anta pwm that was on the treadmill. I was unable to get the upper console which messed me up pretty good since i don't really know what im doing with all this stuff but figured i could work something out.
20200304_202417.jpgthe board has a 9 pin connector for the console. 3 pin for speed and 6 pin for grade. Once i figured out what wires did what i started tinkering with it and got the motor to spin.... but i forgot to put the heat sink on and popped the igbt lol. So i replaced the igbt with a bigger one that wasn't exactly the same but it was close.
The original was a fairchild 12n60a4d and replaced with a STGW30NC120HD. Im not sure what kind of issues that will bring me in the future but it definitely works.

To get the power supply to run i had to apply a pwm signal to one of the 9 pin connector pins. But i couldn't get any frequency or voltage to work. I fumbled around with it for quite a bit and then i made a mistake.... and it worked... perfectly? To apply the pwm speed signal i picked up a chineese stepper motor controller off of amazon for a few bucks.

To make the board work right now i have to do the hokey-pokey.
1. Turn the pwm signal up.
2. Touch the output wire from the pwm to the 9 pin connectors speed pin three times
3. turn the pwm signal down to 0
4. Connect the pwm output wire to the 9 pin connector on the same pin i touched 3 times.
5. Turn pwm signal up and the motor spins throughout its whole range properly.

I set the pwm controller signal output wire on a switch so really i just turn it off and on 3 times rather than touching the wire for now. But im looking to reduce the hokey-pokey effect. It is great to keep people from operating it though.

Also if instead of touching it 3 times i would just hook up the wire and turn it on the motor would take off like a bat out of hell and the board would go out on an overload fault.

Looking for another way to enable speed control on the board.
Does anyone know what is happening? A voltage reference of some sort maybe?
 

MaxHeadRoom

Joined Jul 18, 2013
20,695
Not sure what the PWM frequency is required for that model, the popular MC2100 series uses variable 20Hz PWM control signal from the console for speed control.
Never seen a reverse engineered schematic for that model, unfortunately.
Max.
 

Thread Starter

Kandar

Joined Mar 30, 2020
2
Thank you max for the reply. That made me think about it a bit

I believe i was mixed up. The pwm controller im using right now that works in combination with the hokeypokey varies the frequency and not the duty cycle. And that very well may be what the power supply is looking for. I dont know any different right now.

I also tried going through frequencies with a different controller but it varied the duty cycle rather than the frequency. I searched 1hz to 100hz one at a time with no luck at all. Then did 1 2 skip a few all the way to 100khz. Perhaps i need to try adjusting frequency in the lower ranges rather than duty cycle.
 

MaxHeadRoom

Joined Jul 18, 2013
20,695
As I mentioned in another post today, I can point to a lead on a small PWM board for the MC2100 with pot and stop/start capability, but not sure if it will work with this version of board.
Puts out 20Hz PWM
Normally with PWM, the frequency is constant and the Pulse width varies.
.Max.
 
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