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Theradyne treadmill PWM motor controller fail

Discussion in 'Troubleshooting and Repair' started by keithwins, Apr 23, 2012.

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  1. keithwins

    keithwins

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    Apr 23, 2012
    I have a Theradyne treadmill (discontinued, not supported). When turned on it goes to an E5 error, which is associated with the incline motor.

    I can get the incline motor to run all the way up and all the way down, manually connecting it to power, so I think it's fine. I can also get the treadmill to run for a few seconds at a time, sometimes, so I think the belt motor and PWM controller are fine. I think the problem lies in the "top" control board, which has the input/output switches, display LCDs, etc. There seems to be some history of problems with these machines.

    Anyway: I'm trying to figure out if I can ignore the top board: for example, the incline motor is simple AC, so I can just put an up/down switch on it and run it manually.

    I'm less clear on what I can do with the PWM belt motor. There's a separate PWM motor controller... would that typically be controlled by a digital signal from the top board? There's about 8 wires between the two, I think, and several are power/ground, so I guess it could be some series signal... there aren't a lot of IC's on the PWM controller. I'm including a pic.

    I'm competent at basic electronics, but get lost in the weeds quickly with deeper stuff: I've only got a superficial knowledge of digital electronics, for example, and I'm not strong at troubleshooting power supplies, etc. But I'm a good solderer...

    One of the resistors on the PWM controller had a broken lead that I found, I tested and the resistor seemed fine so I carefully extended the lead and got it all reconnected.

    There's supposed to be some magic way of getting it to do a "calibrate", but despite a LOT of searching (I finally got a copy of the manual: it's not in there) I'm giving up. I can occasionally force it into calibrate mode maybe sorta, but I can never tell what I've done that causes it (it's typically after I've diconnected/reconnected leads maybe 100 times, grounded various terminals, etc). I've never even come close to being able to do it twice in a row, and it's never successfully completed a calibration anyway... Which is why I'm thinking of ditching the entire high-level control circuitry.

    Thanks for any help.

    Keith
     

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  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,412
    2,780
    Jan 21, 2010
    Your fault sounds very familiar.

    It may pay you to search through our threads to see if you can spot another thread (that I'm sure I remember) talking about something eerily similar.

    I'm not sure what the resolution to that one was.
     
  3. keithwins

    keithwins

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    Apr 23, 2012
    I did a search on treadmills and read all those, non seemed to apply. Was there some other aspect of the thread you remember?
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,412
    2,780
    Jan 21, 2010
    It was the incline motor that rang a bell.
     
  5. keithwins

    keithwins

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    Apr 23, 2012
    Treadmills, PWM & inclines

    Yes, one of the posts mentioned incline motors. But it was a considerably simpler circuitry, I think, and it wasn't really analogous.

    I'm wondering if there's some way I can control the PWM motor controller without the (complicated and undocumented) digital "top" board. For example, is there some way to figure out if a simple DC signal controlled the PWM by variable voltage, or is it almost certain that it's controlled digitally, which would be hard to spoof...

    Of course, any other brilliant ideas are welcome.
     
  6. jackorocko

    jackorocko

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    1
    Apr 4, 2010
    That control board you speak can probably be taken out of the equation with some tinkering, but then you will lose all ability to control the treadmill with the buttons and read any of the display information about the treadmill.
     
  7. keithwins

    keithwins

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    0
    Apr 23, 2012
    My choice appears to be 1) loose the given interface or 2) loose the treadmill. I can't find any technical information on the programming interface, I can't even get it to recalibrate consistently, so my hope of muddling through the digital end of it is pretty low. If you've got other ideas...
     
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