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treadmill motor over volts


Jul 15, 2022
Jul 15, 2022
so my treadmill started to throw a error code for the speed sensor after a closer inspection the speed sensor seems to be fine and in working order. when watching the belt it suddenly surges right before the code appears. nothing on the board seems to be burned/darkened and all the capacitors look okay no bloating or leaks. when i checked the power to the motor the voltage was inconsistent and high then shot up to 300v right before it threw the error code. the label on the motor says it maxes at 240v, i tested the motor with a battery and its running fine. currently im not sure what to test or where to look the IGBT seems to be fine for as much i can figure out


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Jul 15, 2016
Jul 15, 2016
If the 300V corresponded to a 25% increase in RPM that's expected, otherwise it was possible just a transient V=LdI/dt from a dry contact relay opening. From some fault condition

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73's de Edd

Aug 21, 2015
Aug 21, 2015
Sir grass . . . . .

the speed sensor seems to be fine and in working order. *****************

Let's initially sort out some particular related board circuitry . . .
Top right corner of component view side of the board are the electronics related to the incline motor and its two black relays . All of which are of no significance to this specific problem. BUT a notable point of interest is the 8 pin mini dip I.C. that sits away from those two black relays (in line with the left one ).
Its function may be related to the input from the white 4 pin ( GRADE) connector in determining its angle readout..
Since I cannot visibly see but the two end pins of it, there is probably a same duplicate unit located to the top left corner of the power transformer . . .off its terminal 10 . . . . now, is that being the same IC type and what are its / their numbers ?
FIO . . . . off the terminal 6 corner, of the blue transformer is the uP brains of the unit, part of its multi functions is to receive speed sensor data pulses and compare to the set speed and send pulse width corrections to the I.C.'s seen at the left corner of the terminal # one of the blue power transformer. They drive the IGBT that is located a bit lower down the board, and then below it is a hefty damping diode for back EMF suppression. ( The blue cased 0.001 / 100 Ω series snubber pair also say . . . . me too . . .ME TOO . . . ME TOO ! )

SUSPICION . . . . .

Reply to ****************** above
Since it is showing an error code for the speed sensor . . .why not check the sensor . . .be it a magnetic reed switch and its associated magnet or a Hall sensor . .you tell us, which type it is.
It could have a mounting error having developed, or some degree of mechanical looseness.
Also, check all of its electrical connection paths and wires from the sensor, all the way to that 4 pin white input SENSOR connector on the PCB top left corner.

i tested the motor with a battery and its running fine
Presumably, with a power tools 18 V Lithium Ion battery pack or minimally with a 12 V car battery . . . . . should give stable speed, very low speed operation testing.

PROCEDURAL . . . . .
You say . . .
when i checked the power to the motor the voltage was inconsistent
That voltage should be relatively stable after starting to walk, with just small variances as steps / loading changes.
Go back to the 4 pin white SENSOR input plug, to the channeled 2nd foil from an end and one of or all three of the other pins should e grounds.
Then, do a DC voltage check to see if there is being that 1 pin that has that intermittent blip from the sensor, if being able to read with the meter. It should be relatively constant . . or if its being " all over the place " . . .that would relate to your IGBT trying to track that " wild input " presented to it.
Once we see what that 8 pin IC is . . . and I am suspicioning it to be a single op amp configured, circuit wise, as a comparator to make a more digitally perfect signal to feed to the uP input.
Knowing that I.C. number, we could then check that output pin from the IC.
But actually . . . . since you already have monitored the input, you could then just monitor all of the I.C. pins to locate the cleaner and higher voltage output that will mimic the previously monitored input. ( Probably it will be one of the IC's 4 pins towards the uP side.)
This is dependent upon the unit being able to run at a slow speed and its being unloaded would opt those run time odds.

from a dry contact relay
this unit uses 3 relays . . . . . the two black ones that power the incline / grade motor . . . so they would be " set and forget " until any change is needed . . . . and are not concerning our problem.
The large white relay is a SPST unit for the DC power that feeds the treadmill motor and has the IGBT in the negative supply leg of the power supply to ground. The variable pulse width driven IGBT regulates motor speed..
That large white power relay is uP powered up initially and then off at uP shutdown command . . . . .so it gets very little use, unless detecting a power consumption fault or shorted IGBT / damper / FWB / 680 ufd main E-cap portions of the system . . . then there is also being the AC line fuse.

. . . . at the A.C. line input terminals, note the nearby mounting pads presences for 2 "Y" capacitors and 1 " X " capacitor . . . . they never were mounted ? Now, did some WANKER from accounting, pocket the funds from not having purchased them ?

ASIDE . . . .
I take this as being a circa 2010 Health Stream unit . . . . but not that we are going to find ANY tech info /or / schematic on it .

QUESTION . . . . .
would the translucent translucent white / clear , larger 6 pin connector in the grade / incline area be harnessed to the display electronics panel?

Now . . . . .what say you ?

73's de Edd . . . . .

Fighting for peace is akin to screwing for virginity.