Hi all,

I have a nordictrack treadmill that uses an MC2100LTS-50W and it won't slow down when the speed is adjusted on the control or even when the safety switch is pulled. If there is no load on it, the treadmill functions properly, but if I am running on it the speed will go up, just not down until I either step off of it, or stomp on it. The status light also doesn't respond correctly, it still shows signal being received while the safety switch is pulled and I'm still running on it. The signal switches off after I step off or give it some resistance (like stomping).

I almost think that it's getting voltage back from the motor, as if I'm turning the motor into a generator while running on it. I could be way off here, but is this possible?

I tried replacing the speed sensor and that isn't it. I could try replacing the motor, but I really don't want to pay for one until I'm sure that would be the issue.

I'm hoping it's not the controls (console) messing up, but with my luck it probably is.

I have a simple bench setup with multimeter and voltage supply, but don't have anyway to generate a pwm signal to test the output/input. Unless it's just a basic servo pwm signal, I do have a servo tester. The board visually looks OK, I don't have much experience probing boards but wouldn't mind learning. I just don't know where to start on this one.

If anyone has any suggestions where to start looking or if you know of something that could cause this I would really appreciate some advice! Thank you in advance!

 

There is a general reverse-engineered schematic here if you search.
The best way really to TS is to bench test with a PWM 20hz signal.
The motors generally are not the problem, you could run it on a Automotive battery to so if acts OK and check for a clean comm etc.

 

Thank you! What would the voltage be on that signal? It would be worth picking one of those cheap pwm generators if it helps me get this working again.

I'll look for the schematic. Not sure if I will be able to determine what's working properly or not, but it's worth a try!

 

I haven't used one of the off-shelf ones, but evidentally they work, as long as it covers 20hz.
you need to calculate the series resistor, which is dependent on what the voltage output of the unit is, the input is a common 817 opto isolator.