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toy repair - motor

Discussion in 'Troubleshooting and Repair' started by tawnyman, Apr 9, 2013.

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  1. tawnyman

    tawnyman

    9
    0
    Mar 20, 2012
    Hi there, I'm trying to repair a motorised toy, it runs off 6 volts of batteries and spins a fan. At the moment it begins spinning and then stops within 2 seconds. The rest of the circuit is just switches and they've checked out ok. Attached to the positive side of the motor is a square yellow componen, shiny finish, about 4mm square. I've noticed that this heated up quite considerably. Printing on it has 2 V's interlocked, one the right way up, the other upside down, follwed by 30 and then UF090. On the back is EIHA China (manafacturer perhaps). The other component, circular orange slightly bulbous disc, is connected between the two motor terminals and has just 104 printed on it. Can anyone a, explain what these do and b, is it likely to be one of these components that is causing the problem. I haven't checked the motor yet because I think that would mean desoldering it all to avoid the bridging component. In hope of learning and fixing, Julian
     
  2. john monks

    john monks

    693
    2
    Mar 9, 2012
    The UF090 is a polyswitch. It is designed to open, that is to internally disconnect, if too much current runs through it. It works by heat. The other component might be a capacitor to help decrease radio interference.
    I am guessing that the motor is defective or is being loaded down too much causing the polyswitch to open. Maybe the battery is not charged enough. Do you have a voltmeter to check these things?
     
  3. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Have you done the obvious and look for dust or hair restricting the fan? Next a little lubricant on the motor shaft might go a long way...
     
  4. tawnyman

    tawnyman

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    0
    Mar 20, 2012
    Thanks for the info on the polyswitch, that's a new one on me so I'll look those up. The item itself is spotless, no dust or anything, I tried the motor with no load on it and got the same response so perhaps it has a fault. Yes, I've got a multimeter, I'll try checking on what voltages and currents I've got running through it. The batteries are new, so that shouldn't be a problem. Checking the motor, what kind of tests can I do on it with the multimeter? Thanks, Juian
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
    2,837
    Jan 21, 2010
    If the motor overheated at some stage it may have a shorted turn in one of its windings. That would cause excessive current.

    It's also hard to determine with just a multimeter.
     
  6. tawnyman

    tawnyman

    9
    0
    Mar 20, 2012
    Thanks for that, I suspect that's what happened then. I'll try to find a replacement motor. Julian
     
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