Treadmill motor control board testing

[vocal]

Hi everyone.
Recently I got running machine with fault and trying to repair it. It switches on and everything seems to work fine (all the settings apart from motor) but when I press start button motor does not start and mcb switches off after few seconds showing E1 error on upper pcb. (E1 indicates motor or mcb problem). After pressing start button, LED (next to big capacitor) goes on. I have 300vdc on motor pinouts with motor disconnected but after few seconds it cutts off showing E1 error. When I connect motor I have about 6vdc and motor does not start showing E1. I have tested motor using 12vdc psu (as advised on some websites) and motor was working. I already replaced thyristor, IGBT and rectifier but still the same problem Any ideas where to start please?

 

[(*steve*)]

I'm thinking the mosfet drivers?

Can you see if they are getting a signal?

What are the 8 pin devices below the mosfets in the first image.

 

[vocal]

Thank you for the reply. I only know basics of electronics so please forgive me silly questions if any.
There is only one 8 pin device and it is mc33153p. The second one is 6 pin and it is tlp561g (white one) How do I check the signal?

 

[vocal]

Done some research and tested tlp561g by shorting pins 4 and 6. No change, still the same problem. How do I test 8 pin IGBT mc33153p? If its faulty can I replace it with mc33153pg?

 

[(*steve*)]

The mc33153pg is the gate driver. It sounds like it's switching an IGBT (and there is one of those, so it sounds right).

This driver has an error output, so the problem is possibly being detected by the driver and being reported back to the uC.

Check the voltage of pin 7 with respect to pin3. Logic high indicates a fault.

The replacement you have located sounds correct, assuming that this is the faulty device.

 

[vocal]

I am getting 0.9vdc across pin 3 and 7 when circuit is on

 

[(*steve*)]

And the device is reporting an E1 error at this time?

 

[vocal]

Yes. It reports error. The error appears on lcd of differen, upper board. When I tried to press start button and kept turning motor manually it was working without problems. However as I said there is no voltage when motor is connected. How else I can check/test mc33153p?

 

[vocal]

Pin 7 of mc33153p is not connected to anything. Should I take more photos of mcb? It just drives me mad

 

[(*steve*)]

OK, if pin 7 is not connected, then that is not causing the alarm.

My next suggestion is that if the error is suppressed by manually turning the motor, then the error condition is caused by some sensor failing to detect the motor is turning.

If the motor works (and I think you've tested that) then the problem must be excessive load or something with the circuit that turns the motor on and off.

Since you're turning the motor by hand, excessive load seems unlikely.

The next step is to see if that chip is being commanded to turn the motor on or not.

Measure the voltage of pin 4 with respect to pin 3 and see if this changes when you do whatever you normally do to start the motor.

BTW, here is the datasheet for that device.

 

[vocal]

Maybe I need to write some more explanation

Everything is connected as it should
I turn running machine on and machine is ready to choose program for running. I can set elevation, time, etc. Then I press start button and motor should start spinning but nothing is happening and after few seconds I am getting E1 error.
I switched machine off and on but still getting the same problem.
I thought that I will try to move belt by feet and see what will happen.
I pressed start button and started moving belt by my feet for more than two minutes and I was getting no error message. At this point I decided to test mcb and motor. I connected motor to 12vdc and helped a bit to start. Motor was spinning slowly but constantly and it needed a little force to stop it by hand so I assumed that motor should be ok. Then I decided to test voltage on mcb motor pinouts and I was getting about 6vdc. As I know only basics I decided to replace thyristor (S6025L), IGBT (SGH80N60UFD) and rectifier (MUR3020PT). One of them was burned out but I do not remember which one.
After replacing above parts I started getting 300vdc on mcb motor pinouts (with no motor connected to mcb). I thougt I fixed the problem and I connected motor back. I was really suprised when nothing has changed and I was getting same outcome as at the beginning.
then I decided to look for help as my knowledge ends here.

The circuit switching motor on seems to be ok. When I press start button I can hear relay and LED next to big capacitor goes on. I will check pin 3 and 4 on mc33153p in 7-8 hours, as no access now, and post results straight after.
Many thanks for helping )

 

[vocal]

I am getting 7.95vdc between pins 3 and 4 either with motor on or off. I checked output as well and I am getting 280mv on pins 5 and 3 with motor on or off

 

[(*steve*)]

That sounds like the signal to turn the motor on is not actually reaching the driver.

We need to step back until we find the signal turning on and off as you try to start and stop the motor.

 

[vocal]

Ok, but how come I am getting 300vdc on motor pinouts?

 

[(*steve*)]

Ok, but how come I am getting 300vdc on motor pinouts?

Does the 300V appear when the motor is turned on, or does it appear always?

It could just be a symptom of leakage through the IGBT. Try placing a high resistance load in place of the motor (say a 100k resistor).

Then measure the voltage across this CAREFULLY.

 

[vocal]

1. When motor is connected symptoms are as follows

Turning machine on - no voltage on motor pinouts
Pressing start button (motor should start) - 6vdc on motor pinouts


2. When motor is disconnected from mcb

Turning machine on - no voltage present on motor pinouts
Pressing start button - 300vdc present on motor pinouts

Motor is 220vdc 6.5A
Maybe I will try to draw schematics if that helps?
However I will try to mesure it with 100k resistor and will post results

 

[vocal]

so I managed to draw schematics for my MCB. I bypassed the part which powers upper pcb and controls elevation motor as everything works on this side. I am hoping I did not miss anything. Any ideas now what can be faulty?

 

[vocal]

Please ignore schematics. Just found mistake. Pin 8 of mc33153p should be also connected to negative of bridge 15v. And pin 4 of mc33153p goes to pin one of little pcb. Will post corrected schematics tomorrow. However if you have any ideas regarding problem with my mcb you are very welcome to advise

 

[(*steve*)]

I think there is more wring with the schematic than you realise

However it is still useful.

One thing to note is that the voltage rails in the upper area of the schematic are deadly. DO NOT attach or remove the probes of your meter while power is applied. Only do stuff when power is removed and do is CAREFULLY. There is a capacitor there, which I assume to be a small value, but I could be wrong.

My observations are:

The S6025L (triac) is probably switching power on to the IGBT and motor. The optocoupler (TLP561G) turns the triac on.

I would expect that your reading of 300V is correlated with a voltage appearing across pins 1 and 2 of the optocoupler (expect a couple of volts at max)

You have already noted that pin 4 of the MC33153P is not getting any signal, so the IGBT (G80N60) can't turn on.

It is possible that you're not seeing very brief pulses being sent to pin 4, and an oscilloscope would be useful here.

I would be tracing back to where pin 4 of the MC33153 is connected and see what's going on there.

 

[vocal]

OK, I was working really hard to draw it. I am not sure if transistors I draw are right as I have got no idea if they are NPN or PNP. Maybe now it will be easier to trace the fault? How do I trace pin 4. Where do I start? I am afraid that little pcb with smd components might be faulty I have osciloscope. What do you want me to test with it?