Trying to save a leafblower cheaply.

Discussion in 'The Projects Forum' started by musicalavtech, Apr 10, 2012.

  1. musicalavtech

    Thread Starter Member

    Mar 23, 2012
    32
    3
    My leafblower had a bit of smoke as the rpm went down on it's own. I took it apart and tested the field coils at 1/2 ohm each all the way to the brush. The coils on the shaft were about .3 ohms between any contacts. I have yet to test the transistor or the speed control switch. Wondering what readings to expect. I know it would be in the megs range (at least for the transistor).

    No real obvious smoke damage going on. The commuter (or whatever coils & contacts on the shaft) looks like this in the pic. 2 contacts are red, looking like the got red-hot. One being scraped somehow and the other seems to have not made any contact. A few wires are black looking. Is it certainly toast?
    [​IMG]

    Link if the pic doesn't show:http://images5a.snapfish.com/232323232%7Ffp635%3C9%3Enu%3D34%3C4%3E7%3A4%3E783%3E25%3B57%3A487425%3Aot1lsi
     
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    It looks like shorted windings (toast) but it's not obvious whether the problem started there or with the brushes or bearings.
     
    Last edited: Apr 11, 2012
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,770
    929
    My guess would be a conductive path developed between the two commutator segments with the charred conformal coating on the wire. You obviously cleaned it very well. With the reported ohm readings you give, it may still work with some new brushes and perhaps an added touch of solder on the two commutator segments. If the old brushes are still useable try them first before you spend any money. A good cleaning may have been all you needed to fix this. The cooked area on the wires seems to be confined to the area of the segments. Where the wire touches other copper wires the charring ends, so the added metal mass was enough to keep it from overheating as much. The rest of the coil is probably OK as well.

    Put a little solder back on those spots and try'er again man!
     
  4. strantor

    AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    Man it looks like your commutator is all chewed up along with the laminations of the rotor. The the balls fall out of your bearing or what? I don't think it's ever going run right, unbalanced as heck.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,770
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    It does look pretty worn down, but then, he did say CHEAPLY :)
     
  6. musicalavtech

    Thread Starter Member

    Mar 23, 2012
    32
    3
    I did not clean anything. That's how it came out. I may try solder. Thanks.
     
  7. svdsinner

    Member

    May 17, 2011
    39
    2
    You probably have shorts in the blackened wires where they cross. If you can separate them and wedge in some electric tape to stop the short, it might work. (Use very little, and possibly add similar amounts of tape to the opposite side to keep the motor roughly balanced.)
     
  8. musicalavtech

    Thread Starter Member

    Mar 23, 2012
    32
    3
    Would heat melt the tape? Would super glue or the equivalent, work after separation? I don't think glue is conductive.

    There is a reset switch that only passes continuity on either set of poles when held in. I should bypass that for testing purposes only perhaps? (Don't want to anger the mods. Ha ha) There is usually a good reason (amp draw) for those to go bad. I would be really pleased if it was the problem. With my luck...NO!
     
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