What is this component?

Discussion in 'The Projects Forum' started by tcawley29, Jan 23, 2013.

  1. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    Hi guys,
    My treadmill stopped working so I opened it up and have determined that this component attached (see image) is faulty because it sparks and trips the tripswitch when I turn on the treadmill. Since Discovery treadmills have gone out of business I cannot get a spare motor controller board but I know I will be able to solder on the new component if I can find out what it is.
    So...What is this black circular component?
    Image: http://img831.imageshack.us/img831/9429/img0243ov.jpg
    Please Help
    Thomas
     
  2. wayneh

    Expert

    Sep 9, 2010
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    The good news is that component is likely a varistor meant to absorb surges. Unlike a fuse, it fails to a short and your device may run fine once it is removed. Of course you should replace it for future protection.

    The bad news is that it blew for a reason, and there may be other damage.
     
  3. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    I'd say it was probably just used when it should have been oiled, dad looks after oiling it. The part literal has a chip blown out of it and sparks when the motor should run. Should I try and remove it as a temporary fix?
    Thanks for your help :)
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Yes, that's worth trying. If all is well, go ahead and get another one. You may want to write down the markings before you remove it - they can get smudged off in handling.
     
  5. wayneh

    Expert

    Sep 9, 2010
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    That wouldn't blow the varistor. It may have simply failed on its own, but they intentionally fail to a short when they see an over-voltage on the line, like from a nearby lightning strike or other cause. They clamp down to a short and this causes a fuse or circuit breaker somewhere else to blow, which helps to protect the rest of the circuitry from the over-voltage spike.
     
  6. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    I tried to remove it there to bring it into the house and get a better look at it but it broke. The last three digits are 135. Any idea what I should be looking for?
    It is connected to a 240v mains supply. would this work?
    http://www.ebay.ie/itm/V420LA10-VAR..._Supplies_ET&hash=item4609de48df#ht_784wt_906
     
    Last edited: Jan 23, 2013
  7. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Most varistors I've seen have a glossy surface, like the one from your last post. The one in your first picture looks more like a NTC to me, although I can be wrong.

    You can easily determine from its position in the circuit if it's a varistor or ntc.
    A varistor will be essentially across the mains voltage (maybe after some other components), while a ntc will be in series with the line voltage, possibly in parallel with a relay contact.

    What component name is stamped on the PCB?
     
  8. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    TVS2 is stamped on the PCB. I tried removing the part and bridging across the two solder gaps where when I turned it on it sparked again. Any ideas what else the problem could be? The onboard transformer could hardly have started putting out too much power could it?
     
  9. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Reread wayneh's first post. If he's correct, you don't want to bridge across where you removed the varistor.
     
  10. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Ok, TVS does not sound like a component name for a NTC, so it is probably really a varistor. As mentioned you can of course NOT short circuit a varistor.

    If it is a varistor you can remove it and test your circuit without it. This is a protection that in normal circumstances is not even being activated.

    The right way to do this repair is to have at least an idea what in-and output wires of the PCB are. I would also draw a diagram of the faulty circuit that contains at least the main components, like for example the varistor.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    A TVS is a "transient voltage suppresser" diode, similar in function to a varistor but maybe more likely to survive smaller surges. (My speculation)

    The device should run without it, once you get past the bridging. Was that solder left over from removing it?
     
  12. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    I removed the component in question and now the treadmill stopped shorting out the trip switch. Now the treadmill shows error e1 when the belt motor is supposed to spin which means motor failure. The motor does work because I have tested it using a drill battery. The relay on the board is also working. Something is wrong that power isin't getting to the motor terminals on the board but I don't know what. Has anyone any ideas?
     
  13. wayneh

    Expert

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    Collateral damage, as I warned. :(

    You'll need to specify the model and look for a schematic. Search "treadmill" in this forum and you'll find a lot of related posts. Some end successfully.
     
  14. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    I still think its only something minor but I ill be testing the components tomorrow hopefully :)
     
  15. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    Okay so I was out messing around with the treadmill again today. When I turn it on and press start the belt won't move and it shortly shows e1 on the display then. I measured the motor output voltage from the control board and its putting out around 13 volts. Has anyone any idea what I should do from here. Thanks
     
  16. praondevou

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    Yes, answer post #13. ;)

    Model# please.
     
  17. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    Apologies, I searched that before and couldn't find my one here. Discovery t1700 :) no model number on the board though :/
     
  18. praondevou

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    Really not much information on the internet about this treadmill.

    Did youcheck for obviously damaged components other than the varistor?

    Fuses, burnt FETs, diodes, resistors etc.?

    Worst case is you will have to draw the schematic by yourself.

    How did you measure the output voltage? Oscilloscope, voltmeter?

    Can you take a high resolution picture of the board, front and back?
     
  19. tcawley29

    Thread Starter Member

    Jan 23, 2013
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    No components visibly burned or damaged apart from the varistor which I removed.
    Fuses fine.
    Thats probably a bit out of my abaility but I'm willing to try if I have to.
    Voltage was measured with a voltmeter.
    I can get pictures up tomorrow morning.
    Absolutely everything works apart from the belt motor running. Incline motor and console display are working perfectly. Belt motor works off an external drill battery but won't run off the motor controller board. The relay definately works on the motor controller board. Really wish I could find out the problematic part because its driving me nuts. I tried starting off the motor by moving the belt by hand but still nothing :(
    Thanks :)
     
  20. BillB3857

    Senior Member

    Feb 28, 2009
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    I'm confused. You say you have 13V coming out of the control board going to the motor. You also say the motor runs with a drill motor battery. Do you have wires connecting the motor to the control board that are bad?
     
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