Issue with JOHNSON FITNESS JDY14PL Revd Control Board

Thread Starter


Joined Oct 16, 2020

I have a TEMPO 621T treadmill, and I am having issues with the drive motor "not running". I have recently replace the belt and I believe while doing that I short circuit the green (vertical) PCB in the picture below. The machine was turned off but I guess the circuit holds the charge for a while but I accidently touched the metal belt roller to it.

The main panels lights up, the inclination works fine but drive motor doesn't run. I have tested the motor with a battery and it works fine. I have limited knowledge about electronics and that way I am seeking guidance from you folks.

The board is JOHNSON FITNESS JDY14PL Revd.

I would appreciate if you can guide me where to start the troubleshooting for this particular board. Thank you in advance.



Joined Jul 18, 2013
Not familiar with that board, but most likely the device fastend to the heat sink is a Mosfet or BJT and would be the prime suspect.
Also check for DC voltage on the output of the bridge rectifier.

Thread Starter


Joined Oct 16, 2020
Thank you Max. I will test Mofset tonight. The voltage on the bridge rectifier is 20V, and the voltage available on the motor connection ports on board is 18volts.


Joined Oct 22, 2014
Hi There. Sorry to hear of the trouble but yep, if you touched that daughter board with a roller and saw a spark, that unit is over. There is a PIC CPU chip on there that is a fuzz sensitive, and I haven't seen these hold a charge for long unless a bleeder circuit fails, as we did have passive bleeders across those larger input caps. The output cap, originally an 820u 16v would hold a charge if powered without a data cable plugged in to bleed it off, but that was less than 12v output so not a lot of sparking available there. Either way, the cost isn't too bad for a new unit, the daughter board is all SMT and coated, making any possible rework rough, and the PIC chip thing makes most DOA. sorry