Proform 6.75Q MC-2000E controller board problems - no LEDs lit

Thread Starter

norton321

Joined Apr 4, 2021
5
Hello everyone – first post here – hope everyone is well - have to say that the amount of knowledge and expertise and willingness to share it on this forum is really impressive and I’m hoping I may get some indication/thoughts on how I might proceed with trying to diagnose a treadmill problem….

My son was given a Proform 6.75q treadmill which the previous owner said ran ok most of the time but on occasion would stop/cut out of its own accord. Generally it would reset and be ok for an unpredictable further length of time. That was really all the information that came with it.

So got it home, checked belt and board which seemed to be lubricated well enough as belt was easily moved by hand. Plugged it in, key put in, and ran it through various speed settings satisfactorily up to full speed with no load.

My son then stepped on at slow speed and everything seemed fine, but as speed was increased, the belt slowed and stopped. He stepped of the belt, reset and tried again. Pretty much same thing again, but accompanied with a faint ticking noise from under the cover, like a contactor clicking in and out rapidly.

Took off the cover (found an unopened PETL5602 Proform6.65Q Voltage Diagram inside taped to underside) and switched it on again.

The voltage diagram explained what each of the 4 LEDs on the MC-2000E Rev 1.03 control board meant – and they all behaved as described under a no-load test up to full speed. However, on a further no-load test up to full speed, after a few seconds at full speed, the motor suddenly went into slow speed for about 5 secs, stopped and then all the LEDs on the board slowly went off.

Turned everything off, checked if motor was hot which it wasn’t, not even warm, and waited 15 or 20 mins (hoping it maybe was the thermal switch after all) before powering up again. Still no LEDs on board lit at all. Checked power to board with mulitmeter and getting 230v at AC1/LG1 and AC2/LG2. No burning smells and nothing on controller board looks burnt or damaged. Elevator works fine.

Checked motor in both directions with 18v rechargeable battery – runs smoothly and quietly both directions and brushes look fine.

Going by the voltage diagram details, the controller needs to be replaced. But at £140 approx replacement cost here in the UK, I am prepared to try and fix this controller or look for a cheaper and simpler alternative controller before dumping it.

(unfortunately, whilst happy and safe working around electricity and reasonably good with a soldering iron, my PCB trouble shooting skills are rubbish and I even struggle on occasion with some of the component terminology – so I need to be treated like a dummy when having something explained. I have never been inside a treadmill until now)

So I am wondering are there likely culprits here, things I should check first, anything that I might be able to fix or replace to get this working again?

I assure you ANY help will be gratefully received and very much appreciated

Regards….norton321
 

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MaxHeadRoom

Joined Jul 18, 2013
23,090
That is one of the last SCR bridge versions before they went to PWM control, i.e. MC2100 versions.
It would appear that HD4 is the 5k pot input on that version, so it should be capable of running on its own with a POT attached, unfortunately I have not come across any reverse-engineered schematic for that model as has been done for the MC-60/MC2100 series etc.
 

Thread Starter

norton321

Joined Apr 4, 2021
5
That is one of the last SCR bridge versions before they went to PWM control, i.e. MC2100 versions.
It would appear that HD4 is the 5k pot input on that version, so it should be capable of running on its own with a POT attached, unfortunately I have not come across any reverse-engineered schematic for that model as has been done for the MC-60/MC2100 series etc.
 

Thread Starter

norton321

Joined Apr 4, 2021
5
Thank you for reply, Max
HD4 runs up to control panel pot as you say. What do you mean by ".. it should be capable of running on its own with a POT attached.."?
I've posted better picture of board - hadn't noticed part of original pic was missing.
I've removed mosfet IRFP32N50K and as far as I can tell with the diode test on the multimeter, its faulty.


























"
 

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Thread Starter

norton321

Joined Apr 4, 2021
5
I meant run the board stand alone from the console on the bench by powering it and if needed, attach a separate pot to the HD4.
Ah, ok. However, despite having 230v power at AC1/LG1 and AC2/LG2 on the board, all LEDs are off and the board has no output at LG3/A+ and LG4/A-, irrespective of the console pot position. The voltage diagram states that if the controller board is powered up and the 15v led in particular doesn't come on, then the controller board needs to be replaced, suggesting something is wrong with the controller board. I'm trying to identify what the most likely components to have failed are under the circumstances detailed in first mail and test accordingly.
If mosfet IRFP32N50K (behind the big cap) is faulty as it appears to be, are there likely to be other associated components worth checking?
 

MaxHeadRoom

Joined Jul 18, 2013
23,090
If it is the same type as the MC-60 etc, it would be the two SCR's and the two diodes on the heats sink that runs the motor?
If so, Not sure what the function of the Mosfet is?
.Unless I have it backwards, the SCR's are for the incline motor and the Mosfet for the belt motor
 

Thread Starter

norton321

Joined Apr 4, 2021
5
If it is the same type as the MC-60 etc, it would be the two SCR's and the two diodes on the heats sink that runs the motor?
If so, Not sure what the function of the Mosfet is?
.Unless I have it backwards, the SCR's are for the incline motor and the Mosfet for the belt motor
OK - I'll investigate / test some more and get back if I come up with anything of use. Thank you for your help Max
 
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