Diagnosing a Jazfit Treadmill Power Control Board

R!f@@

Joined Apr 2, 2009
9,918
Been Bzy for a while, I can hardly find time to relax and think abt ur problem. :(

Finally got a break. I have looked at ur schema and photo. Since I do not have them in my hand my assumptions are based on your schematic.

The mini board could be the culprit. I would asked you to replace it, if you can, but I doubt it.
So as any good tech would do I would tackle the components on the mini board.

I am trying to redraw your schema. I need to see how the mini board is connected to the opto's. Watching at the photos I can draw a good schema but the tracks under the chips is something you have to trace.

Something just hit me, so I would like you to measure the Voltage level of all the pins of the PWM controller (TL494) on the mini board.

Measure with reference to the mini board ground. Be careful since you will be poking the HV DC area of the tread.

Be careful not to slip the meter probe, as a slip might blow the PWM driver together with the Power switches.

Take the measurement in idle & run modes.
Post all the Voltages at the pins of the TL494.

Keep in mind to observe the tread as you probe the board.

When done, measure the voltages at all the pins of LM339 chip on the mini board. Both at Idle & Run.

Post everything and anything. Info is very important. :D
 

thatoneguy

Joined Feb 19, 2009
6,359
I'm running out of ideas here.

Haven't seen anything odd, other than something the uC is detecting is causing it not to fully power up/enable all systems. It seems much like a stuck safety switch somewhere, but those have all been checked. :confused:
 

R!f@@

Joined Apr 2, 2009
9,918
I'm running out of ideas here.

Haven't seen anything odd, other than something the uC is detecting is causing it not to fully power up/enable all systems. It seems much like a stuck safety switch somewhere, but those have all been checked. :confused:
Hah !! that's why I'm the Man :cool:.

I never run out of Ideas...:confused:

But...........

Could be the safety feature....we did ask abt that lotta times..No!!
 

Thread Starter

pokethebear

Joined Nov 25, 2010
57
Once again, thanks to everyone for your assistance. R!f@@ sure has determination ... dog with a bone :)

What's maddening is that it seems like such a coincidence that it happened right after the machine was moved. Just screams bad solder joint, or ... safety switch. I'm sure that most of us have been sidetracked by the obvious things before though, and of course it doesn't have to be one of those. It's just the timing of the fault that bugs me.

The main safety switch appears to work fine. With the opto output bridged, the tread runs. When the safety switch is activated, it stops the tread like it should.

Couple of questions, that perhaps your experience with treadmills can help with:

1. Could there be any other safety switches that I just can't see?

2. Random: what is XTAL1 on the console board near the processor?

When I reattached the miniboard, I also reflowed the joints where the pins connect to the miniboard itself. Tread still no go after that.

I would like to reflow a few more solder joints on the console board ... I have clips now that I can use on the IC pins to help keep me from cooking the ICs, which I didn't have before. Old soldering skills are coming back as well :p

After that I'll take those measurements on the miniboard, but it will be a few days. I got a work contract in that is pretty urgent. Will update as soon as I can.
 

R!f@@

Joined Apr 2, 2009
9,918
XTAL is the crystal Oscillator...the fact that console works tells you that XTAL is working

There is no other safety switches as far as I know of
 

ian_gregg

Joined Jan 19, 2011
21
What happened to this thread? I have just found it and read through 11 pages to find a dead end. I have the same treadmill with the same symptoms. I am also in Brisbane, not flooded but been busy helping others. Hope pokethebear did not go under.

The schematic is a big help and a lot of work. I will try to add some component values.
 

Thread Starter

pokethebear

Joined Nov 25, 2010
57
Hi ian_gregg, I'm glad that the schematics have at least helped a little. It might be good for you to follow and perform all of the tests that R!f@@ has already had me do, if you haven't already.

We were working real hard on this fault until before Christmas, at which point my workload got super crazy. Then Christmas happened, and then the floods. It's currently on hold until I find time to get back into it, sorry about that.

I'm in the northern suburbs of Brisbane here and wasn't directly affected by the floods at all. Of course some secondary effects are hitting us, but that's most people in the area right now.

So we've basically gotten up to the mini board attached to the power control board, and R!f@@ has given me a bunch of tests to do on that. To do those, I'll have to wire a harness to the mini board to make it more accessible to probing with power applied. I'm trying to make time for that. I'm sorry to hear that your tread is doing the same thing, but perhaps it's a good thing that we may be able to learn from each other.

The mods may want you to start your own thread for your machine if you want assistance, I'll be following it if you do.
 

ian_gregg

Joined Jan 19, 2011
21
Some component values to add to the schematic:
R2 1k0
R49 1k0
R33 180k
R34 39k
R35 1k8
R36 270k
R37 470k
R16 68k
R14 15k
R26 1k2
R17 220R
R4 22R
R24 don't know the value but it will be small R for current sensing
R26 150k
C26, C27, C28 all 220n
It looks to me as if the components you have as C21, C22, C23 are actually designated CZ1, CZ2, CZ3 and I think they are some sort of protection device that will pass DC up to a certain current limit which also makes sense as the current sense resistor should have a DC connection to pin 7 of the miniboard.
D4 measures about 0.3V on diode test so it is a dual schottky diode, from the part number 300V, 60A
 

ian_gregg

Joined Jan 19, 2011
21
My reading of the schematic is that the console should apply voltage to pin 5 of the connector, only needs <1V to turn on Q5 which turns on the opto and applies a signal through a delay network to pin 4 of the mini board. To turn on the motor supply, the mini board should send ~24V on pin 9 to turn on U1 with 10mA through D8 and R26 to +12V. To run the mini board sends PWM pulses out on pin 1. While the motor is running, pulses through Q4 hold D6-K low and hold U1 on with 12V on pin 9 of the mini board.
 

ian_gregg

Joined Jan 19, 2011
21
Console connector
Pin 1: high turns on relay RY1, applies 240VAC to the bridge BR1
Pin 3: high to raise
Pin 4: high to lower
5V will operate these, each is through a transistor to a relay coil.

As 24V does not seem to be anywhere on the mini board connector, could there be a connection from D8-K, R26, C19 to the mini board that is pulled down to turn on U1, Q2 and the 300VDC supply? I don't have my board out yet so it is difficult for me to trace the details.
 

ian_gregg

Joined Jan 19, 2011
21
Damm, I have made it worse. I think I shorted pins 5 and 6 of the console connector with the console connected and the smoke came out of U15 on the console board. The dead ant will not work after the smoke escapes. It is so fried that I cannot read the part number. My console is quite different to pokethebears but I am hoping to get some hints anyhow. U10 nearby is a HC14 and I am thinking U15 is the same but it would be great if pokethebear could confirm the part numbers of U2, U3 on his console, I think I can see HC14 on U3 on the pic that has already been posted but it is not really clear.

small_IMG_0001.JPG

small_IMG_0002.JPG

small_IMG_0003.JPG
 

Thread Starter

pokethebear

Joined Nov 25, 2010
57
Ouch ian_gregg!

Thanks heaps for the values. I'll look into getting them into the schema as soon as I have 5 seconds to rub together ... I'm job hunting right now and it's taking all my time + extra due to the floods. So many people looking for work :(

If my console board was the same I'd at least go find the part number now. Good luck!
 

ian_gregg

Joined Jan 19, 2011
21
pokethebear

If you could just confirm the part numbers on your console board U2, U3, U8 that would help, thanks.

What sort of work are you looking for?
 

Thread Starter

pokethebear

Joined Nov 25, 2010
57
I'm pretty sure of the numbers on U2 and U3,

U2 HD74HC02P
U3 HD74HC14P

I'll get you U8 and double check U2 and U3 tonight or tomorrow, hopefully.

I'm looking for web design / development work. I've been freelancing in it for some years, along with authoring related training courses. Work has gotten scarce of late, and the floods have made it worse
 

thatoneguy

Joined Feb 19, 2009
6,359
I'm pretty sure of the numbers on U2 and U3,

U2 HD74HC02P
U3 HD74HC14P

I'll get you U8 and double check U2 and U3 tonight or tomorrow, hopefully.
Luckily, those two are very common and low cost parts, 7400 series CMOS Logic ICs, usually under $1 each. It's just the soldering if you aren't good at it. Time will tell what U8 is to see how bad things might be.

Do you have a DMM (digital multimeter?) If so, you should check voltages before shorting together wires, or at least resistances when off, it results in less destructive troubleshooting, though "plugging it in and replacing everything that smokes" IS a useful troubleshooting method when all else fails. :D
 

ian_gregg

Joined Jan 19, 2011
21
Back at this after a long delay. Removed my dead U15 and noticed that pin 1 was an output and pins 3, 5, 8, 12 were all connected to ground so decided it was a 74HC02 used as an inverting output buffer.
 

R!f@@

Joined Apr 2, 2009
9,918
I see we have new comer......Sorry I LMAOF reading about that short, couldn't help myself.
Just reading through, ian, you do what you can, I'll jump in when everyone else gives up.

I have a lotta things going on these couple of days.
 
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