York Pacer 3501 Treadmill Fix

Thread Starter


Joined Oct 30, 2013
Hi All,

This is my first post to the forum.
This post is not asking for help but to assist others who may have the same or simular treadmill which needs repair.

I have a York Pacer 3501 treadmill which had a problem of, after selecting any speed the motor would go flat out for a few seconds, then it would stop with ERR2 on the display, which means overspeed.

I have drawn a rough circuit which has most of the signal path for diagnosis.
The Motor Drive PCB is marked HS-T300Series

The procedure I followed was-
1. Connect the motor to a power supply and it operated correctly needing approx 30V to go 1.0 Kmph.
2. Tested the IGBT (Q2) which seemed OK.
3. Tested voltage at the Gate of Q2 which varied as I sped up & slowed the motor. This pointed to the control circuit being OK.
4. Replaced Q2 & D1 anyway as they could be breaking down with high voltages. No change in the symptoms.
5. Drew out the circuits to assist in the diagnosis.
6. Operated treadmill with isolation transformer so I could test signals through the isolated parts of the circuit with an oscilloscope.
7. All voltages were within tolerance, signal from motor seemed OK at 500Hz for 1.0 Kmph. Signal at T1 14V p-p and varied duty cycle as speed changed from power supply.
At this point I was confused as the symptoms indicated a short across Q2 & D1.
8. Tested motor for resistance and found there was a near short from the motor -ve terminal to chassis. pulled apart motor & discovered a build up of carbon from the brushes across the insulation between the -ve brush housing and the case. Cleaned up the build up & now all working.

The only thing that is not correct is the motor appears to be running a little faster than before possibly 10-20%. This doesn't seem to present any problems until you go to max speed of 12 Kmph where it will shut off after a few seconds giving the ERR2. As I don't use the treadmill at max speed this shouldn't be a problem for me.

Thanks for a great forum.