g Treadmill (Proform/Domyos) controller board Fault

Thread Starter

MihaiBrB

Joined Mar 19, 2022
48
First of all hello to everyone !
I just started electronics a short time ago as a hobby and now got into treadmill repairs.
The main issue i have posted now is that i have 4 MC2100 controller boards at home ( 3 form domyos and one from a Proform) which are identical.

To start from the beginning...when i received this boards all of them had the IGBTs shorted.
I proceeded to replace them with same component.
I also have a treadmill for test with 2 dc motors.Both motors test 0.9 ohms between black and red leads ( dont know if that is ok )

When powering up the boards for test the following happend on all of them:
-upper display powered up and board LED got solid red !
-hit the start button , LED start blinking fast and the motors started moving
-the motor starts aggressively at high speed ( the upper control panel just shows speed 2 ) demanding 20 Amps at start-up then the speed goes down in 2 seconds and getting stabilized getting 8 amps !
-after 1 min at running at the start speed, without load, the IGBT gets very hot and shorts along with IGBT driver

I have replaced again the IGBT , IBGT driver , THYSTOR , Bridge rectifier , some smd resistances near the IGBT driver.
Did the test again.same results on all the boards with both motors.

Any ideas?
Thank you in advance !
 

MaxHeadRoom

Joined Jul 18, 2013
25,638
For a start, it is much easier to trouble shoot these boards on the bench with just power applied and a PWM controller plugged into HD2.
There is a couple of ways on the internet using either a 555 or a unit off ebay for a 20Hz PWM, I made up some small boards with a Pimicro to run them.
Ensure the ramp up SCR is OK also,.
Do you have the reverse engineered schematic that has been posted here and other sources.?
 

Thread Starter

MihaiBrB

Joined Mar 19, 2022
48
For a start, it is much easier to trouble shoot these boards on the bench with just power applied and a PWM controller plugged into HD2.
There is a couple of ways on the internet using either a 555 or a unit off ebay for a 20Hz PWM, I made up some small boards with a Pimicro to run them.
Ensure the ramp up SCR is OK also,.
Do you have the reverse engineered schematic that has been posted here and other sources.?
yes ive gone trough the schematics.it seems that a pwm signal comes from the upper controller panel..hmm.and i can replace that signal by pin HD 2 ?

and which is the ramp up SCR ?
 

MaxHeadRoom

Joined Jul 18, 2013
25,638
It is also on the heats sink, on the schematic it is Q1.
HD2 is pin1 & 8 = GND, pin2 = +12VDC and pin4 is the 20hz PWM signal. there is only a 22ohm resistor on the input to the opto, so any source provided has to add a series resistor accordingly.
.
 

Thread Starter

MihaiBrB

Joined Mar 19, 2022
48
It is also on the heats sink, on the schematic it is Q1.
HD2 is pin1 & 8 = GND, pin2 = +12VDC and pin4 is the 20hz PWM signal. there is only a 22ohm resistor on the input to the opto, so any source provided has to add a series resistor accordingly.
.
thank you ! i will check
 

Thread Starter

MihaiBrB

Joined Mar 19, 2022
48
It is also on the heats sink, on the schematic it is Q1.
HD2 is pin1 & 8 = GND, pin2 = +12VDC and pin4 is the 20hz PWM signal. there is only a 22ohm resistor on the input to the opto, so any source provided has to add a series resistor accordingly.
.
Q1 seems to be S4025L ..thats a 25 amps thyristor and i did replace it
 

MaxHeadRoom

Joined Jul 18, 2013
25,638
Even if the console displays a fast speed, it should always ramp up, to avoid blowing any semi', it can also be tested with a alternate load such as an incandescent lamp etc, but it is easiest to trouble shoot by eliminating the console first with the independent bench test of the main board first.
If you intend pursuing trouble shooting these boards, it is invaluable.
 

Thread Starter

MihaiBrB

Joined Mar 19, 2022
48
Even if the console displays a fast speed, it should always ramp up, to avoid blowing any semi', it can also be tested with a alternate load such as an incandescent lamp etc, but it is easiest to trouble shoot by eliminating the console first with the independent bench test of the main board first.
If you intend pursuing trouble shooting these boards, it is invaluable.
thank you.i will try to get a 20hz pwm module
 

Thread Starter

MihaiBrB

Joined Mar 19, 2022
48
Even if the console displays a fast speed, it should always ramp up, to avoid blowing any semi', it can also be tested with a alternate load such as an incandescent lamp etc, but it is easiest to trouble shoot by eliminating the console first with the independent bench test of the main board first.
If you intend pursuing trouble shooting these boards, it is invaluable.
i also tried with light bulb..that seems to light up ok.
can you please link a pwm module to buy ?
 

MaxHeadRoom

Joined Jul 18, 2013
25,638
Where are you located?
I believe some have used these Ebay No 234234349937.
Also some on Amazon.
Mine does not have the display, not that it is really needed.
 

Thread Starter

MihaiBrB

Joined Mar 19, 2022
48
Where are you located?
I believe some have used these Ebay No 234234349937.
Also some on Amazon.
Mine does not have the display, not that it is really needed.
and stupid question..to power the pwm module i can use the pins from the controller board ? i got 9v there.. and i can use the 9v with the gnd pin to power the pwm module ? and use pin 4 and gnd( because there are 2 gnd pins) for pwm output ?
 

MaxHeadRoom

Joined Jul 18, 2013
25,638
The one I put together does exactly that, it uses the pins 1&2 for power and PWM into pin 4.
There is a DIY design out there using a 555 IC for the PWM.
 

MaxHeadRoom

Joined Jul 18, 2013
25,638
Yes 20Hz.
Did you observe fitting a suitable series resistance in the lead of the output, depending on the output voltage?
Have you got the input on pin4?
 
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