Treadmill Stops Running after 7-10 minutes

Thread Starter

julnov

Joined Nov 24, 2020
4
Hello,

Preamble: I am not an engineer but I am interested in keeping my treadmill working and out of the landfill if possible. I have been trying to find people with similar problems as mine and been reading lots of forums lately but not sure if they have the same problem or not. I usually end up on this site so I thought I try posting my problem to see if someone can point me in the right direction however I have very little knowledge of circuits.

Problem: I have a Smooth Fitness 6.17 treadmill that stops between 7 and 10 minutes (I set the speed at about 7km/hr for the duration) although the display says it is still running, no error codes on display or on control board. I have taken apart the motor (IMG_6376) and cleaned it up, brushes look fine to me and there is no thermal switch and therefore no 3rd wire. I have also disconnected the motor belt from the running belt so only the motor is running for that time and the same problem still happens. After the motor stops I connect the main leads up to a 12v cordless drill battery and it runs fine, however connecting the leads back to the control board it does not run. If I wait about 4 hours then the treadmill will start again but usually run for a shorter time, about 5 minutes. If I wait 24 hours then the treadmill starts again and runs for the usual time.

Analysis: Based on the behaviour, it sounds like the problem is somewhere in the control board as I have eliminated the running belt as the current problem. What I have read and understood it sounds like the semiconductor chips embedded in the heat plates (circled in red in the attached picture IMG_6366) are not functioning properly anymore. Also attached is a close up of those chips once I unscrewed them from the heat plates (IMG_6363). I am tempted to buy and replace them however I am not sure my analysis is even in the ballpark. There is also one more chip that is in the heat plate IMG_6364 but I'm sure what its role is. Also tested resistance on the bridge rectifier chip and it appears to be functioning normally (reads O/L on opposite pins). Also if it helps, attached is the another picture that shows the board ID IMG_6275, it doesn't appear to have any capability to display error codes either.

Also I realize that the problem on the control board was likely caused by the running belt not being lubricated and being too tight which added additional load to the motor and caused the problem I am experiencing now. So once I fix the current problem I will make sure the running belt is working properly too.
 

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MaxHeadRoom

Joined Jul 18, 2013
23,115
What you need is some Freezit or Artic Air, several go by different names, but it is an aerosol that brings the temperature of a device down drastically.
This allows a faster diagnosis as to what device is monitoring the temp.
Look for Thermal dependent resistors.
Max.
 

Chiho9

Joined Oct 18, 2020
20
Since the thread mill isn't running, the problem is most likely to be from the motor. You should probably check the part of the circuit board responsible for controlling the motor operations. You could consult a technician to check it out
 

Thread Starter

julnov

Joined Nov 24, 2020
4
Thanks for the quick reply!

Okay, so best to cause the problem and then start spraying chips & resistors to see which one allows it to continue, correct? Do I need to put the heat plate on again first too? I would guess yes otherwise that could cause further problems.
 

Thread Starter

julnov

Joined Nov 24, 2020
4
Okay got a hold of some "Super Cold" and put the board back together. Ran for about 12 minutes before it stopped. Sprayed on suspect chips, still no movement. Started spraying on other chips and waiting for a few seconds, still nothing. Sprayed other diodes and board in general and then in ran for about 7 minutes again. No idea spraying which chip caused it to work though! Waited about 7 minutes and sure enough it stopped again. Okay started spraying again, slower this time, waiting about 10 seconds between sprays and then when I sprayed the diodes above the red wires attached to board it started working. Okay, I thought I would let it run and then try again. However after about 6 minutes the fuse blew! Tested the bridge rectifier again and now getting voltage reading from + back to AC even when I switch the positive and negative leads on the multimeter. So looks like the bridge rectifier was slowly dying and I helped it along. Yes I did spray it initially too just might have taken awhile to cool down? Does this behaviour lead you to believe that it could be the bridge rectifier?
 

Thread Starter

julnov

Joined Nov 24, 2020
4
Also I disconnected the power, bypassed the fuse with some wire and then when I plugged it back in, the motor started spinning immediately even though the panel said the treadmill display said it is stopped. I unplugged and removed the bypass wire immediately!
 
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