Need help finding compatible SC used for variable speed control of DC motor

Discussion in 'The Projects Forum' started by jack6128, Nov 29, 2012.

  1. jack6128

    Thread Starter New Member

    Nov 22, 2012
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    Hi, I hope I'm posting this in the right forum. I have a Ryobi P230 impact driver that has lost its variable speed function. It only turns on and off. I suspected that a semiconductor had failed so I broke into the switch. I found a transistor-looking device (voltage regulator?) and remove it from the circuit. Sure enough, there was an intermittent short across two of the leads. I can replace it, but I can find absolutely no information on it. No site has a data sheet for it and no site has a compatible. I am hoping someone here can steer me toward a possible compatible component.

    The failed transistor-looking device is made by Fairchild in what looks to be a TO220 package and has the following two designations on it:

    N349AH
    and below that is:
    M0255507

    Not even the Fairchild site has any info. I suspect that this component is pretty standard for this application. The battery that drives the motor is 18 volts. Any suggestions?

    Thanks,
    Jack
     
  2. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    A lot of tool manufacturers have component parts supplied with part numbers unique to them. It may be a standard part with a Ryobi part number just to keep you from making a repair. Have you tried to see if Ryobi has a repair part facility. May be the entire speed control is available from them. I own a Craftsman 19.2V drill and internal parts are not available for it, according to Sears.
     
  3. jack6128

    Thread Starter New Member

    Nov 22, 2012
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    0
    Hi, Bill, and thanks

    The switch assembly is available at about $50 delivered. A new impact driver costs $70. A cheap transistor of this type costs 3 or 4 bucks. It might be worth a roll of the dice if I knew what TYPE of transistor it was. The driver still works in the on/off mode, but the variable speed function is nice and I miss it.

    Jack
     
  4. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    The info I just gave on my Craftsman drill is in error. I was going on info I got a couple of years ago during a telephone inquiry for the trigger assembly. I just found it on line from Sears Parts direct for about $35. Either Sears has added parts for the drill to their inventory, OR I talked with someone that didn't know how to find it. Your post made me look again. Thanks.
     
  5. debe

    Well-Known Member

    Sep 21, 2010
    946
    184
    All that ive come across have N channel Mosfets not transistors.
     
  6. jack6128

    Thread Starter New Member

    Nov 22, 2012
    10
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    Thanks, debe! This gives me something to go on.

    Jack
     
  7. debe

    Well-Known Member

    Sep 21, 2010
    946
    184
    This is the Mosfet STP45NF06 that is in this unit. More info at Alldatasheet.
     
  8. jack6128

    Thread Starter New Member

    Nov 22, 2012
    10
    0
    Thanks Daryl, I ordered that part from Digi Key for $1.25 plus $2.80 shipping.
     
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