I have a Smooth fitness 5.25 treadmill that I used to use as my walking desk, but has been collecting dust for a few months now. It stopped running, just like that.
Trying to start it up now blows the line circuit breaker.
If I take the motor leads off the board then the display lights up and the incline motor runs just fine.
I measured the voltage that the control board is trying to send to the motor, and its around 170 VDC.
I actually took the board out and sent it to someone who promised to fix it - no help after $150 spent, still blows the line circuit breaker if I hook up the motor.
By the way, I tested the motor with a car battery and it runs fine.
Also, just before the circuit breaker pops, the belt attempts to run, for maybe 1/2 an inch or so.
I'm open to ideas about the control board itself or, alternatively, suggestions about a reasonably-priced Variac+rectifier+capacitor bank design. I would still wire it through the safety key switch, but would not mind if I had to turn a knob to adjust the belt speed.
Thank you for any and all ideas.




.

 

What happenes if you replace the motor with a dummy load like a lamp?

 

What happenes if you replace the motor with a dummy load like a lamp?

Did not try it yet.
Will do it later today and will report on the findings.

 

Tried it this morning and the bulb lit up just fine, no problem at all.
In my layman's opinion, the circuit breaker pops with the motor hooked up because the control board is putting out 170VDC and the motor immediately is trying to run very fast, pulling too much current.
The voltage control part of the circuit must be inoperative.
Now, if anyone could point me in the direction of which component(s) may be responsible for this.
I will post a photo of the control board later today.

 

Is it full on right away? It should start with the lamp off and ramp up.
If it is full on right away, that indicates a shorted power semiconductor.
Max.

 

It is full on right away. Measures around 170 VDC between the M+ and M- terminals. I will post a picture of the control board later today, maybe you could point out the potentially defective component.

 

Also any Board model No. such as MC2100 etc.
Max.

 

Will look for it

 

I have taken the photos, will attempt attaching them here.
A bit more background.
When this first occurred, months ago, I kep trying to get it going, to no avail, as it kept plowing the circuit breaker, until finally it sparked and hissed, and smelled burnt. Now. it was completely dead.
At that point, I found a blown power diode (F10U60DN) - obsolete part.
Called Digi-Key who found a replacement: DIODE ARRAY GP 600V 10A TO220FP.
Soldered that in (it is the one on the right, on top of the picture, behind the clamp, barely visible, black component).
After soldering it in, the unit was back to its misbehaving self - blowing the circuit breaker on every start-up attempt.

 

Need to identify and test the semiconductors clamped between the aluminum heatsink.
Max.

 

Back again as the treadmill is collecting dust.
A couple of months ago, I found one of the MOSFETs was bad, replaced it and VOILA - the treadmill came alive. Alas, the happiness was short-lived - after about a half hour or even less, it froze up again.
However, the terminals to the motor are now reading 0 volts, so no more blown fuses, just a dead stop.
I am contemplating the following:
Buy 10-20 amp Variac (0-120 VAC); feed the 110 V AC through the safety key to the Variac and its output to a rectifier bridge, connect the DC output to the motor input, add a large capacitor to act as a filter.
The incline motor still works fine. I could control the belt speed with the Variac.
I would really appreciate your critique of this idea.

 

I'll probably do the same thing with mine. for now I'm about to test a 200W 12V halogen downlight transformer to see if that's enough power to let me walk @ abt 1kph @ 130kg size 14 shoe.