I have noticed that there have been posts on this controller on various forums and so far no one has reverse engineered it, which is about the only way to do any reliable trouble shooting.
The first step is to check the obvious suspects such as power devices, if all else fails, it may be worth taking time to reverse engineer and map the circuit out.
Max.

 

Hi Max or anyone else with input, I have done as much of a circuit drawing as is possible without trying to unpot the controller can in the middle of the board.
Does that help in trouble shooting this board?

Its not a pretty drawing, top right is the 5 pin plug leading off to the user control panel 10v AC from transformer. 3 other pins are up/down speed select from user control panel.
The 17v AC also from the transformer supplies the two volt regs.
The 9 pin block is the potted can.
Motor terminals are + side of the bottom bridge and the motor neg as marked.
Resistor values are in the photo list.
This last photo is of the inside of the potted control can, not mine (thanks to another on a different forum) but an earlier revision, just to give an insite as to whats in there.

 

I'm getting frustrated now, on lockdown here in the UK so I spent more time on this KXTL 230 controller. I removed the mosfet and fast diode. Both tested ok, I replaced the IRFP460C with another new one anyway after pre testing the new one with a multimeter to be sure it was good. I wired a 50k pot across the 3 pins leading to the user panel so I would be able to turn on the mosfet on the bench. I connected a 100watt lamp across the motor output terminals. The heatsink chassis was left off so I could measure voltages on the circuit board.
I powered the board up and the lamp lit but very dim, maybe 50v dc, I quickly adjusted the pot to see if I could turn the motor output up/down but no response. then the output went to max 330 vdc. All this is within 45seconds, the 460C case got extremely hot with no heat sink and I powered down.
Assuming the 460C was now toasted I removed it and metered it, it was still fine so what caused the sudden full turn on, I dont know.

 

Dear oldman2,

Did you find any solution for the issueM
I have the same circuit board, probably same threadmill, sadly the same issue.
330V DC output for motor.
Checked IRFP460C and F10U60DN, both look fine.
Adjusting pots changed nothing on output.

If you have the solution since, could you please let me know?

Thanks.

 

Dear oldman2,

Did you find any solution for the issueM
I have the same circuit board, probably same threadmill, sadly the same issue.
330V DC output for motor.
Checked IRFP460C and F10U60DN, both look fine.
Adjusting pots changed nothing on output.

If you have the solution since, could you please let me know?

Thanks.

No, sorry I got no further, the fault is I am sure in the circuitry enclosed in the potted PWM can which you cannot access. I have been able to run the machine using a 3rd party motor controller but thats a fudge. So no good news from me, sorry.

 

Some meter may indicate AC due to the large ripple on the bridge output.
Max.

Some meters will read voltage on the AC ranges even with clean DC going in. They have a rectifier but are not capacitor coupled so DC gets through.
Most multimeters on AC ranges are only suitable for reading a sine wave with zero DC offset.

 

Best to scope it!

 

I dont have a scope. If someone in the UK would like to take this on as a lockdown project I would be quite happy to post it to them.

 

Jolyon posted some interesting mods to add pwm to the control board, getting rid of the canned and potted original pwm. https://forum.allaboutcircuits.com/...or-controller-jd-230-e-e.167042/#post-1603546

After reading and making all Jolyons mods I connected the control board to the treadmill and checked the Jolyon replacement header on the board for control volts and found it missing the 12v and 0volts then the penny dropped, I had blindly followed Jolyons detailed instructions to the letter, or rather pin number and I had cut off the pins as shown, pin 1-3-5 when on my version of the board 12v was pin 1 and pin 2 was not used along with pin 4. pin 3 was 0v, so once I removed the incorrect header and replaced it using pins 1,3,5 & 9 it worked as designed. I did need to replace the mosfet as this had indeed failed again, maybe the wrong pin header helped it on its way.

So the Jolyon Nano replacement for the canned up original pwm does work but I was now getting a mechanical klonk every 1/3rd of a second caused by the pwm. Feed the motor from another source and no noises, so I talked to Jolyon and he suggests altering the sketch lines thus:

commenting out this line should stop the sketch pausing each .3 second to check the current.


//current = analogRead(0);


also change the number of cycles between reads from 1000 to 10000. This will mean speed updates every 3 secs instead of 3 times per second but this shouldn't be a problem.


for (int i = 0; i < 10000; i++) {


I have yet to retry mine with the above sketch edits but thought it best to report back here in case anyone else follows blindly as I did, remember to check your control board pinouts are the same as Jolyon's if not alter pins used to suit yours.
Its not perfect by any means but you can now control motor speed from the main console. You would need to fine tune the sketch to match the given to actual speeds, but at least it works.

 

Further update: With the modified sketch the knock has gone but the motor has a high pitched whine which Jolyon says cant be cured due to the Nano not being entirely suitable for the task.
I wonder if someone can get this 555 timer circuit that I found on a forum working on these boards to replace that "can"

 

I received the board with the same problem that the mosfet was burned and after changing it with a IXFH21N50Q mosfet and the output to the motor without load is 330vdc, other voltages such as 8 volt and 12 volt dc are OK, can anybody help me with this.

 

I suspect like mine the metal canned PWM controller is faulty giving a turn on full signal to the mosfet at power on. The drive motor tries to run but the overload is such that the fuse blows but not before the mosfet is killed.
If you carefully desolder the can and substitute the Jolyon Nano replacement you can then test if all behaves as it should, except there will be a motor noise.
If this test works fine then the "can" is faulty and as its potted there is no way of repairing it so you then need to devise a PWM controller of some sort, maybe using the 555 timer circuit I posted.
Dont forget to post back here if you have any luck so others can gain from the work.