Been chasing down a problem with a NordicTrack 1750 treadmill. control board MC2100LTS-


So far have replaced the mosfet Q4 3 times. Keeps burning them out as soon as I power the motor.

Have tested the unit with A bulb and voltage reader after swapping the mosfet out. The unit will operate as it should. Indicator light goes from solid red to blinking steady and ramps up the voltage as you increase the speed.

As soon as I put the power to the motor it’ll burn a mosfet. Have tried without the belt attached and it does the same thing.

it started while using the unit the belt hadn’t been serviced so it caused extra strain on the unit. Once the mosfet goes out the indicator light will blink 4 times after trying run for a split second.

I tested the motor itself and the ohms were good even went as far as taking it apart and checking the com it self and the rest of the assembly did not find a single issue. Cleaned it and reassembled it. Check the wires that connect the motor to the board and found no shorts. I haven’t retested the unit since opening the motor itself and cleaning it but doubt it’ll make any difference. I had already ran it with a 9volt battery and it turned.

Any suggestions on where to proceed from here? Should I just get another board? Afraid the same thing will happen to the new one if it’s something else I’m missing.

every other function of the treadmill works as it should though.

 

Test the SCR DC ramp circuit, this is how the DC to the motor is slowly applied at start up.

 

Test the SCR DC ramp circuit, this is how the DC to the motor is slowly applied at start up.

Wouldn’t the test with the Incandescent bulb which showed the voltage ramp up as I increased speed show it was working?

 

Did you do a lamp test in place of the motor?

 

Did you do a lamp test in place of the motor?

Yes sir the Volts ramped up accordingly.

 

Hello there I have the same board in question and I'm looking to identify the following components.
R51
R46
C28
C29
All these blew up on a unrecognizable state, thank you in advance.
By checking previous post I guess that U8 is STR G5551. Not sure if both C28 & C29 have the same value 50v 33 micro F.

 

R51 BR,GRY, BLK = 18Ω
R46 RED, BLK, GOLD =2Ω
C28, C29 = 33uF

 

R51 BR,GRY, BLK = 18Ω
R46 RED, BLK, GOLD =2Ω
C28, C29 = 33uF

Thank you!

 

R51 BR,GRY, BLK = 18Ω
R46 RED, BLK, GOLD =2Ω
C28, C29 = 33uF

Max, got all the parts could not the same value for R51 and C28 C29 so I got the resistors in series and the caps as well to get the right resistance & farad. After assembling back together the board back in the treadmill panel does not light up. It appears that something else has been damage. Any idea when to start troubleshooting?

 

I assume you have checked the 12v (or so) DC supply on pin 1 & 2 on the HD2?
This is what the devices you changed creates.

 

I assume you have checked the 12v (or so) DC supply on pin 1 & 2 on the HD2?
This is what the devices you changed creates.

I did and nothing.

Can I connect the board by itself to 120v and able to check for 12v without the panel and the rest of connectors from the treadmill?

 

What I would be inclined to do is scrap/remove the SMPS parts just replaced and fit a separate 12VDC supply and feed it into what was the output of the SMPS, this is how the first MC2100's were done, they then installed a 12v supply linear transformer supply (Bridge & Cap) on board.