Hi All, my apologies for the absence. Ok, you have all done well, I must say I am proud, no horror stories, that's good!
There is a schematic in my head, I had it taped to the wall in front of my desk for about a year as we worked at correcting this unit from its rapid inception after a recall for previous Horizon treads which I remember happening in 2002 or 2004. But that's a whole different story.
This control board revolves around a pic16f687f if I remember, requires encoder feedback at your 5-pin connector from the rear of the drive motor, 177-teeth/slots per revolution, front roller feedback after 1.5sec, an active pwm drive from the upper board, and an active enable also from the upper.
The Light(LED) near the larger capacitors is an "energized" LED indicating the motor rail now has lethal power available, seriously
I may have mentioned a 220 ohm resistor by an output filter cap that may be a 22 ohm and is almost always covered(hidden) by white staking compound or glue. This resistor opens at times, is a chip resistor, careful replacing when needed. Sorry for that error.
Repairs for this board as you have read include the FET, kickback diode, check for console power at the 12-pin connector(long white connector) telling you the onboard power supply is working, this is usually about 15v at 3A(max) from the vertically mounted 3A diode near the small transformer. The lead coming from The top bend is the cathode, and has DC console power here referencing "DC GROUND" which can be found carefully at zener D4 anode or a nearby smt regulator.
DO NOT CROSS GROUNDS!
Crossing grounds, of which there are 3 on this board, a) Hot Ground - caution!, b) DC GROUND used by the console and all human interface points, and a totally separate power GROUND. Whew....be extremely careful!
I hear folks talking about 18v on the motor tabs....first, do not try to run any controller without a motor connected! The control board watches for a legal motor(inductive load) or it will sense an open and disallow any Red LED or motor rail power. The 18v people see on these tabs with or without a motor attached is a precharge voltage of 18vdc. This is not a source for the motor power, it is a biasing voltage to stabilize the super Hot motor rail for energizing.
If we didn't precharge this rail, we would weld relay contacts 50% of the time, and that just wouldn't work well, nor would we have a rational stable circuit at energize time which is a caustic in rush. Therefor, we precharged this rail.
Next, if your 3 storage capacitors are domed at the top, replace them, they are shot. Bulging tops are a sure sign of internal overheating and severe degradation, for a couple reasons I won't go into, just trust me, 3pcs of 560uf 200v caps.
The pic chip or uPc or cpu on this board requires the said feedbacks, pwm, enable, clock, power, and an internal programmed lookup table for speeds and regulations along with safety stops and a "dual relay" safety design for the motor rail.
You will see 4 relays. 2 up front for lift up and lift down. Then an L-shaped safety relay and a smaller relay right next to it.
When a user presses start....enable active to lower board, sanity check for powers and valid feedback for lift potentiometer. Next pwm begins, pic chip gets both and now engages small relay to precharge large capacitors for .2sec, energizes main safety relay, disables small precharge relay, checks all voltages, motor rail, motor sense, waits for feedbacks for 2sec, if valid full regulation and lift enabled upstairs and belt is turning.
For repairs look up fitness remedy in Sun Prairie wisc, there is no better fitness electronics repair depot in the US.
Good luck all....thanks for the kind words I've seen!

Hi IamJatinah,

I am new here and I need your help please.
I have the same board, mine power up red LED lit, deck control works but nothing move.
belt motor works on drill battery,
Elevation motor stuck at the highest position, removed and twisted manually to the lowest position, connected back and once the power is on it started to elevate automatically without any warning and can’t stop it without disconnect the battery.
Which parts should I replace on the board?

your help is highly appreciated.
Thank you

Moderator edit: New thread created from this.

 

Hi IamJatinah,

I am new here and I need your help please.
I have the same board, mine power up red LED lit, deck control works but nothing move.
belt motor works on drill battery,
Elevation motor stuck at the highest position, removed and twisted manually to the lowest position, connected back and once the power is on it started to elevate automatically without any warning and can’t stop it without disconnect the battery.
Which parts should I replace on the board?

your help is highly appreciated.
Thank you

Hi There, This sounds to have multiple issues going on, no belt movement along with unwanted lift command. The lift can be commanded higher if the potentiometer inside the gearbox opens and the console can no longer read the position of the "throw" of the lift. In this case it sounds unlikely with another issue happening. This actually sounds like either an upper console board failing, possible cable issues between the lower and upper board sets, or multiple failure points on the lower control board which I couldn't hip-shot without seeing and measuring a few things. Good Luck, if you are in the UK, there is a fella there that does repair them but I have gotten pestered if I steer folks anywhere ;o)