I would like to thank those involved with this thread https://forum.allaboutcircuits.com/...ol-board-johnson-fitness-jdyf02l-revg.110355/ for all the good information about this control board. By using a combination of info, test procedures and some troubleshooting logic I was able to make a successful repair. I dabble in electronics here and there and haven't even used an oscilloscope since college. It was satisfying to troubleshoot, test and learn/re-learn along the way. Here is a list of where I started in the troubleshooting process. I've also made a very rough and partial circuit diagram with information from the board and datasheets. I hope this can help someone also looking to fix their treadmill.

As usually, the treadmill "isn't working". It powers up and displays everything as normal, however when the start button is pressed (and a few beeps are heard to tell the user the belt is about to move) the motor does not start...most of the time. Sometimes there was movement but mostly nothing. Let's do all the preliminaries like check fuses, loose connections and other anomalies that may keep the motor from starting. All looks normal. I also put a meter on the output to the motor while attempting to start...nothing. All I can here is the relay turn on and after a brief timeout period, turns off. This was an indication to me that certain criteria is being met but a malfunction is preventing the motor from starting. I did also see the red LED turn on letting me know the motor rail has power. Thanks to the discussions from the above thread, the picture of how this board operates and the common failures becomes more apparent.

Time to test stuff! I powered down everything and let the capacitors discharge before removing the board. Since the mosfet Q4 and diode D4 were common failures I removed them both and tested on a breadboard. They both tested without a problem. Now I need to dive deeper into the circuitry of this board and HOW it actually works. For that I need a diagram. Since I could not locate a schematic online I decided to draw my own. I tried to be thorough with connections, component descriptions, part numbers, etc. Using my trusty multimeter and the continuity function, I was able to come up with a partial diagram involving most of the components related to turning on the motor (power and signal). Armed with this homemade piece of information it's time to put the board back in and do more testing.

As I mentioned before, I haven't used an oscilloscope since my electronics courses in college some 20'ish years ago. This is a problem. Enter google and the owner's manual. After some tinkering I followed the PWM signal all the way back to U2 pin 8. This is the spot where I could actually see a waveform on the oscilloscope when I hit the ON button for the board. So somewhere between pin 8 and the PWM test spot the signal is not making it's way through. I then looked at the optocoupler U4 as a possible failure source. I would occasionally get a signal every time I tested the "led" pin of the optocoupler. The only component between my two testing points is a resistor labeled R48 (220 ohm). All my problems can't be caused by a resistor?? I tested for continuity directly at the solder joints connecting R48 to the board. Seemed very erratic to say the least. Also tested resistance and found 350'ish ohms?? I decided to replace it.

Plugged everything back in and to my enjoyment the treadmill started to work again! It's now been over a week with daily use and no issues. Thanks again to those involved.

 

Hello Folks¡ Good day to all¡

@usagoal I'm sure you felt amazing after fixing your machine¡¡ Congrats¡ and thank you very much for giving us your time to share this valuable information. It has been very useful to me.

I have a similar issue with a Horizon T101 board JDYFL REVg treadmill. If you have any opportunity to know my story and perhaps give me guidance I will be very grateful.

My wife treadmill turns on normally, console start, inclination works fine, but when I press Start the motor starts for 2 seconds and then stops. As I like to take things apart, and occasionally I like to put them back together again so I thought this would be easy as to change a FET or some old school resistor ... I was very, very wrong, these guys from Johnson & Johnson know well what they do. I was scared when i see the board as in my time there was no SMD ...

Reading @usagoal message and the ones from @MaxHeadRoom, @IamJatinah, and all this great community has given me great guidance and the motivation to repair it by myself but I have not been successful so far... maybe some good soul from this great community can help me with this

I done basic tests with the old school Fluke on every diode, resistor, SOT 23, relays (tested with 12v battery and all clicked), bridge rectifiers, electrolytic capacitor and FETs with no obvious shortages so far except for some details:

1. Two SMD resistors: R39 (reading is 29kΩ and should be 47kΩ) and R40 ((reading is 31kΩ and should be 62kΩ)
2. 2 inflated capacitors: C19 and C20 (I replaced them with 1000 uF 25V ones as I couldn't find the original 820 uF 25V ones) is this good?
3. I also replace the FET with a new IRFP260n as the previous one had very erratic readings.
4. I don't know if I am testing SMD capacitors correctly, I am doing it with the DMM on capacitance, I get values from some of them but some others I get readings like 0uF I don’t know how to get the value of uF from each one as they are so small...
5. I also tested the motor successfully with a 20V drill battery... however I am thinking of get a lab dc supply to make sure the motor works 100% ... Is this a good idea?
6. I Also note that when I disconnect from the board both speed/light sensors and hit start, the motor turns on for almost 5-6 seconds instead of 2 (and I get 34v on R and B) ... when the sensors are connected I only get 5v for 2 seconds after pressing start.

With the information that I provide, did you guys think that is a good idea to replace the resistors? as im testing those ones on the board im not so sure if mi readings are good ones but all other smd resistors mark the expected result... @usagoal diagram helped me a lot but it also made me wonder if I'm looking in the wrong place and maybe I need to check somewhere else....

Excuse me folks if my English or definitions are not the best. I am just an old school very enthusiastic nerd with free time due to the pandemic so any question I’ll be glad to share.

 

I am planning to buy a used "JDYF02L Johnson Fitness Motor Control Board - Horizon CST 3.5 Treadmill ". Will it work as-it-is in "Horizon T7.6 treadmill" or I will have to re-program it somehow? Both the boards, the board I am planning to buy and the one I currently have in my machine, have "JDYF02L REVg" printed on them.

 

I would like to thank those involved with this thread https://forum.allaboutcircuits.com/...ol-board-johnson-fitness-jdyf02l-revg.110355/ for all the good information about this control board. By using a combination of info, test procedures and some troubleshooting logic I was able to make a successful repair. I dabble in electronics here and there and haven't even used an oscilloscope since college. It was satisfying to troubleshoot, test and learn/re-learn along the way. Here is a list of where I started in the troubleshooting process. I've also made a very rough and partial circuit diagram with information from the board and datasheets. I hope this can help someone also looking to fix their treadmill.

As usually, the treadmill "isn't working". It powers up and displays everything as normal, however when the start button is pressed (and a few beeps are heard to tell the user the belt is about to move) the motor does not start...most of the time. Sometimes there was movement but mostly nothing. Let's do all the preliminaries like check fuses, loose connections and other anomalies that may keep the motor from starting. All looks normal. I also put a meter on the output to the motor while attempting to start...nothing. All I can here is the relay turn on and after a brief timeout period, turns off. This was an indication to me that certain criteria is being met but a malfunction is preventing the motor from starting. I did also see the red LED turn on letting me know the motor rail has power. Thanks to the discussions from the above thread, the picture of how this board operates and the common failures becomes more apparent.

Time to test stuff! I powered down everything and let the capacitors discharge before removing the board. Since the mosfet Q4 and diode D4 were common failures I removed them both and tested on a breadboard. They both tested without a problem. Now I need to dive deeper into the circuitry of this board and HOW it actually works. For that I need a diagram. Since I could not locate a schematic online I decided to draw my own. I tried to be thorough with connections, component descriptions, part numbers, etc. Using my trusty multimeter and the continuity function, I was able to come up with a partial diagram involving most of the components related to turning on the motor (power and signal). Armed with this homemade piece of information it's time to put the board back in and do more testing.

As I mentioned before, I haven't used an oscilloscope since my electronics courses in college some 20'ish years ago. This is a problem. Enter google and the owner's manual. After some tinkering I followed the PWM signal all the way back to U2 pin 8. This is the spot where I could actually see a waveform on the oscilloscope when I hit the ON button for the board. So somewhere between pin 8 and the PWM test spot the signal is not making it's way through. I then looked at the optocoupler U4 as a possible failure source. I would occasionally get a signal every time I tested the "led" pin of the optocoupler. The only component between my two testing points is a resistor labeled R48 (220 ohm). All my problems can't be caused by a resistor?? I tested for continuity directly at the solder joints connecting R48 to the board. Seemed very erratic to say the least. Also tested resistance and found 350'ish ohms?? I decided to replace it.

Plugged everything back in and to my enjoyment the treadmill started to work again! It's now been over a week with daily use and no issues. Thanks again to those involved.

Got a treadmill with same controller board on a trash day. Initial check showed motor not running. Left it in my back patio for years. Trying to clean house but trash pick up gas limit of 70 lbs.
i started to look in to repair instead dismantle the machine.
Thanks the above link and your post.
mine also has a dead R48. Completely open for the 221 resister.

I started to troubleshoot the usual suspects on all the Power components and started to draw diagram myself. I should have registered earlier to see your diagram. Very helpful when i downloaded it today.
Before this, i got to the lethal side and comparator. And opto parts. Everything seemed fine. Had to disconnect the board many times to test and retrace the board. I dont see pwm signal to the receiving side of opto coupler. It has pull up voltage only. Board is covered with heavy white glue, making it difficult to trace the board.
i was about to see how i can tap the opto diode side to see where the pwm stopped. Then your diagram showed the ttl ic output to r48 and opto.
took me awhile to find the location of r48, tp4.
Like what you said. how could it be a resister problem. A simple resistor test revealed r48 is open.
need to find 220 omg replacement now. Maybe i will check pwm signal from U2 output after work tomorrow.
Note i know at least this resister is bad.

other fun findings. Controller has three separate ckts.
1, power side with nFet and kickback protection, highcurrent ratifier.
2, smps ckt of the 16v. This one does not look like have opto coupler feedback.
likely for medium power components such as upper board displays, and cooling fan for exercise.
The two optocouplers are for pwm pass over to power side and safety feedback from the 18v pre charge check, TL521.
3, the usual 7805 to get5v from the 16v smps to digital ckt side.
Took me awhile to figure how the safety system works since i have never used this treadmill. The L shape safety relay kicked in and then click of after 10sec.
motor won’t move.
if i manual move the belt after pressing the start button, the safety relay will continue to engage. This tells me how the feedback sensors are working. Eg: roller sensor, 177 teeth sped Senator, pwm generator, 16v supply, and the pot from incline. The irf260 fet to not switching on because it is not getting pwm signal. Bjts seems fine from onboard dvm tests. Not seeing pwm from receiving opto chip.
I just started to use a portable mini oscilloscope. Maybe i didn’t print correctly. Haha…. ( never have my own scope before, quite a newbie to use it).
Will see how repair will do. don’t have smd parts for flow station. R48 is on the edge so u could use standard iron to replace it.
will continue this fun.

 

I hope all goes well with your repair. For me, it was a nice challenge to resurrect what electronics knowledge I had in college. I find great satisfaction that this post was useful to someone at some level. Please keep us updated on your findings and if the repair was successful. This was a good machine for the 10 years that we had it.

 

I hope all goes well with your repair. For me, it was a nice challenge to resurrect what electronics knowledge I had in college. I find great satisfaction that this post was useful to someone at some level. Please keep us updated on your findings and if the repair was successful. This was a good machine for the 10 years that we had it.

I hope all goes well with your repair. For me, it was a nice challenge to resurrect what electronics knowledge I had in college. I find great satisfaction that this post was useful to someone at some level. Please keep us updated on your findings and if the repair was successful. This was a good machine for the 10 years that we had it.
[/QUOTE]
Finally got the replacement smd resistor. And it worked. Treadmill is running now.
had to trace the board stage by stage.
this failed resistor did not sense as TTL drives the opto led directly. Maybe the resistor wattage is under size. Will see how long this will run.
Thank you.
your info as well as IamJatinah helped a lot, and without those, i would be spending quite some more time to reinstalling the board to test and trace the ckt.
thats why i love internet of sharing knowledges. Please keep up the good work.