Precor Treadmill Repair

My wife enjoys running on a treadmill, and that has become even more important with COVID occurring on top of the Canadian Winter. We were fortunate in being gifted a Precor 932i treadmill from a family member who was downsizing. It’s been rather decent for a while, throwing the odd error code here and there. However, in the height of the lockdown it decided to give up working.

Over the course of its life it’s had a few blips of throwing an Error 30. I chalked this up to the data cable running between the upper control panel and the IFT Drive going bad. It looks like a standard ethernet cable, so I replaced it and the issue persisted. For those of you wondering how to access the error log on your Precor, hold down the reset button for 15-30 seconds, then to clear it hold down the QuickStart button for 15-30 seconds.

Then something strange happened, after power-cycling the treadmill the incline motor started running and wouldn’t stop running. The treadmill proceeded up to its maximum lift height and a new error code was produced. Error 42 “Lift Position Out Of Range”.

After doing some googling I was a little frustrated with how it seems that Precor would rather have you call a vendor than troubleshoot anything on your own. There appears to be very little documentation on how their treadmill systems work. I was able to find a troubleshooting section from a different model of treadmill here.

At this point I suspected the IFT Drive (Motor Controller) had failed and I was looking to see if someone could validate my diagnosis as I have zero experience in troubleshooting gym equipment. Reaching out to support to validate my diagnosis they mentioned they thought it was the lift motor itself. In case you were wondering the prices on these, the IFT Drive was around $700 USD, and the lift motor was around $370 USD. A lot of money for a old hand-me-down treadmill.

Determined to not spend the money I figured I’d do some research. I was able to access the diagnostics menu and go to the incline test. The A/D test, which stands for Analog to Digital test was showing very odd numbers, they were jumping around. This test is effectively showing the output of the potentiometer that is inside the motor. This is used so that the treadmill can track how far the lift system has moved.

Looking at the lift motor I had in the treadmill it was a “SKF Actuation System (PingHu)” Model: MJ8245. I did some quick googling to see if I could find a used one perhaps, however since I have the 220v treadmill that was a bust. Lots of the 110v versions were kicking around on Ebay, but none for my version.

I pulled the motor out of the treadmill and checked the resistance between the positive and negative power lines and that seemed to be good. So now my attention turned to this little potentiometer. I took the motor cover off and found it. Model: RV4NAYSD102A. Looking online I was able to find one on digikey for $17+$8 shipping for it to be overnighted.

After replacing the potentiometer it was better. I had to power the treadmill on and navigate to the incline test, and dial it into 0.0 incline manually. After installing it back into the incline motor I tested the treadmill and suffered another round of run-away incline. After some investigation the plastic gear that the potentiometer is fitted into was slipping. To me this is not a great design to depend on only friction for your lift control.

I ended up coating the wiper of the potentiometer with machinist blue and that itself provided enough friction for the lift function to work as expected. I still get a few error 30’s now and again which I’ll have to investigate later. However for now I’ll consider this fixed.

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