Troubleshooting a treadmill control board

Discussion in 'Technical Repair' started by HH1, May 14, 2019.

  1. HH1

    Thread Starter New Member

    Oct 22, 2018
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    0
    Hi,
    I have a MC2100ELS-18W (rev -) motor controller from a treadmill that I am trying to repair. I don't have the console that was used in the treadmill so I'm currently trying to control it from an Arduino Uno. The board looks OK, no traces of burnt component ( very slightly darker on one pin of the flyback diode and the IGBT).
    First, when I plug the board to the 220AC (Europe), the STR component (W6251) make noise and the LED is solid red.
    Then, when I input a PWM signal to the board with the arduino (5V 50ms period square signal according to what I've found about the MC-2100 and other sources), my motor have an impuls without really starting. Without a motor connected or with a small one (500W) the led then blinks twice every 15sec or so, with a bigger motor (130V DC, 2.8HP) the led would blink 4 times in 15sec. The measured voltage without a motor are the following : 15V without PWM signal, it reach 70V when I send a signal and then slowly decrease to 13-15V (capacitors discharging ?) .
    There is also a problem with the incline motor command : when I apply 5V to the down command , nothing happens, however if I measure voltage (with a multimeter) between the up command and GND at the same time, the down relay activate, I measure 4.3V at the up command and the STR noise stop.

    I've already replaced the STR but it doesn't change anything so I'm looking for anyone that could help me having any input about my problems.

    I attached two pictures of the board

    Thank you for your help and sorry for my english, it's not my mother tongue.

    Henri H.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    17,739
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    I built a controller for these using a pic 12f IC. The PWM needs to be 20Hz.
    There are previous posts of mine on the MC2100, see Here
    I would suggest also trying the motor whith belt disconnected.
    What technology is the incline motor? some were induction.
    Max.
     
  3. HH1

    Thread Starter New Member

    Oct 22, 2018
    4
    0
    Hi,
    Thanks for your quick answer.
    Couldn't the Arduino provide accuratly enough this pwm frequency ?
    I have read your previous posts about the MC2100 controler, you seem to know this card pretty well and I'd like to thank you for all the information you shared.
    I actually only have the DC motor and the card so all the previous tests where made without the belt. I intially thought that it could be a problem with the speed sensor (simple reed switch) but the motor does not turn at all so it might not be about speed sensing by the reed switch.
    For the incline motor, I don't have it but it is only controlled by two 220V AC relay one controlling the up direction and the other one the down direction (3 pins on the lower left corner of the first picture).
    To give some context, I'm planning to reuse this board and motor for tools in a wood workshop so I don't really need the control over the incline, however I found this behaviour quiet odd and thought that it could be somme useful information for troubleshooting the PWM control. I really don't understand how connecting a multimeter connected on other pins could change the behaviour of the board.

    Thanks,

    Henri
     
  4. HH1

    Thread Starter New Member

    Oct 22, 2018
    4
    0
    Ok, after drawing the part of the board controlling the incline motor (do you know a simple free software to draw clean circuits? Maybe I could post it on the forum for other people) I realized that when trying to control it, I connected the UP command to 5V but didn't connected the DOWN one to GND. That's one problem solved :) :) Still a big one open :(

    Henri
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The RPM detector is not required and AFAIK goes to the console where it is handled there for display etc.
    I have never used an Arduino, but imagine it is up to the task, same as the Pic.
    But apparently the PWM has to be fairly close to the 20Hz.
    You need the correct series resistor for the opto isolator that receives the PWM and is sized according to the voltage input, in my case I use a 5v signal.
    I use free Kicad now, but a bit of a learning curve.
    Max.
     
  6. HH1

    Thread Starter New Member

    Oct 22, 2018
    4
    0
    Hello,
    That's what I thought I had read about the reed switch, but because of the many different versions of the MC2100, I gave it a try.
    Yes, I didn't burnt (yet) the opto for the PWM using 5V however I may add a small resistor on PWM control as you did (even if the arduino can only output 40mA I think).
    Do you think that the problem on my board could be the SCR circuit controller ? I think that it may close at the beginning and immediatly open. I tested the SCR and it behave fine (~500k resistance between anode and cathode, and way less if I short the gate with the anode) .
    During my tests yesterday, I burnt the fuse for the low voltage part and a .56ohm resistor, so I cannot do more tests before I get the new parts (hopefully tomorrow). :mad: (My hand ripped and the multimeter created a short circuit between +9V and GND).
    I got time to draw the incline part if that can help someone one day, it's fairly easy and symetric. I linked a picture of the circuit with this post. However, I am not sure about the transistor types and connections (those very small components are hard to identify), so it might be wrong because of that.

    Thanks for your advices,

    Henri
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    17,739
    5,396
    The F817 opto LED series resistor is only 22ohms so any added series resistor depends on the voltage of the source.
    It is 50ma maximum.
    Max.
     
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