Nordic Treadmill - board MC2100E REV D ICON 2007

[Dipam]

Hello,,, I am investigating and repairing a treadmill for a friend. On powering up incline motor fine, when pressing start the mains breaker of the house trips (so a BIG spike I believe)... Motor is P.M.D.C, P/N F-214366 2.5HP 130VDC/1865W... I am an engineer and have product tested for electrical safety in the past for SGS electrical... Anyways. I checked the DC motor, opened it apart, took out the core, cleaned between the copper commutators, checked the resistance between all points. And ran the DC motor on a seperate external DC supply at approx 10-30 V and motor ran smoothly. Brushes are fine. So I checked the removed the D.C motor connection from the board (board is MC2100E REV D ICON 2007). Motor disconnected, power on treadmill ok. When 'start' no tripping. Then I measured the D.C output voltage on the board. Before starting the run with mains power on, there is a 10V D.C reading,, when starting the RUN it reads over 300V (320V) then drops slowly down approx 10V per second from 300... To me this seems very high??? as motor rating is only 130V D.C. Can you advise please?? regards . Dipam

 

[MaxHeadRoom78]

The DC for these units uses a SCR to ramp the voltage up slowly, the DC itself is derived from a Bridge across the incoming AC so it will measure as ~160, but the motor average voltage is controlled by a PWM signal into the Mosfet.
It is really best to run a bench test with the main board removed, but it requires a 20Hz PWM signal into pin four of the HD2 connector.
I have a reverse-engineered schematic for these that covers most models, or you can find it on the AllAboutCircuits site where I posted a few times.

 

[MaxHeadRoom78]

Reverse eng schematic

 

[Dipam]

THank you so much for responding,,,, i have seen many of tour posts and am impressed at your tech and input to help others. And here now wirh me... my plight is deeper in that O want to help a friend save money on getting this Nordic treadmill working again. O am not charging, i opened and inspected before any real 'dismanteling'.. systematic inspection from plug to board/motor controls etc.... but my electronic knowledge is limited, but i learn fast and have an engineering background... so logic prevails ... sometimes... electronics are long overlooked with the youth of roday,,, as articles before, a problem on a pcb board, replace board 10p/200/300... find issue component,,,, pennies if not a few pounds/dollars.. and the satisfacrion of learning and fixing and and and...

 

[Dipam]

So Max,,, i have already stripped the motor to its elements,, all seems fine, ran it on a seperate DC supply, smoooth... mah i ask my use of a multimeter to measure DC output for the belt motor (removed)... i know the signal is a pulse width modulated output... but i am still wondering that measured 300+ DC output voltage (albeit on no load),,, am i doing this and reading all wrong??... aplreciate feedback... we learn and learn. Thankyou

 

[MaxHeadRoom78]

Probably due to zero load, you can also test to some extent using a 100w lamp in place of the motor.
Very rare to see any problem with the motors.
Most of the issues are with the semi-conductors mounted to the heat sink.

 

[Les Jones]

Have you checked the insulation between the motor brushes and the motor casing using an insulation tester. (I suggest the 500 volt setting. I am assuming your mauns voltage is about 240 volts as you measured 320 Dc off load.) It is posible that there is a fault which is putting full power straight to the motor. If this is the case the starting current to the motor may be enought to trip the breaker. Try connecting a mains voltage FILAMENT type lamp with a rating of about 100 watts in place of the motor. The speed control should change the brightness of the lamp.
Does your main breaker trip due to over current or earth leakage ? If you are in the UK the ,ain bteaker normally trips on earth leakage but each circuit is protected fo over current by an MCB.

Les.

 

[rjenkinsgb]

If Q2 is shorted that could cause an overcurrent trip, with the motor trying to instantly start on over 300V DC...

 

[MaxHeadRoom78]

Re-reading the OP the 130VDC/1865W...motor would be for 230V supply, the 95vdc motor is used on 120v version in N.A.
If full DC appears when the motor is activated, it is usually the SCR.
Also the heavy flywheel aggravates the problem when applying immediate full power to the motor.
The way the controller works, is it applies full PWM signal whatever speed is required, but the DC is ramped up at the same time, via the SCR in order for a soft-start.
I made up some Pic Micro 20Hz PWM controllers for bench test purposes.
I have so far found that the motor has never been the problem.