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    Trying to repair a Bosch JS470E jigsaw - component ID?

    Can someone identify the component at the end of the grey wire? The little resistor looking piece attached to the white rectangular PCB.
    I accidentally smashed it while attempting to fit the components into the plastic housing after replacing the brushes, and now whenever the switch is depressed, my lights dim and the motor stalls.
    It is also housed approx 5" from the main board, so I'm assuming it has something to do with heat management.
    It is part of the electronic speed control module from a variable speed jigsaw.
    It looks like a 4.7kohm resistor but replacing it with a new one did not fix the issue.

    Specific part number:1607233559

    https://www.ereplacementparts.com/el...p-1117953.html

    Thanks for the suggestions.

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    Re: Trying to repair a Bosch JS470E jigsaw - component ID?

    Looks like a 4.7mH inductor but why it is mounted on a second board is a mystery unless it is to sense the magnetic field from the motor. When it is assembled, where does the little board sit inside the body, it is along side the motor by chance.

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    Re: Trying to repair a Bosch JS470E jigsaw - component ID?

    It sits maybe 4" away from the board next to the motor.

    In the pic I've attached, the red rectangle is the location of the module, and the grey wire runs to the component, which is inside the red circle.

    Thanks for replying! This has been driving me crazy and bosch tech support has been no help.

    Click image for larger version. 

Name:	jigsaw.JPG 
Views:	7 
Size:	94.6 KB 
ID:	152525



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    Re: Trying to repair a Bosch JS470E jigsaw - component ID?

    A possible reason for mounting an inductor close to a motor, is to detect when a stall occurs. Then it can trigger a shutdown to prevent extreme current levels in the motor windings.

    However I don't know how such a function might account for what happens when you operate the saw:

    I accidentally smashed it while attempting to fit the components into the plastic housing after replacing the brushes, and now whenever the switch is depressed, my lights dim and the motor stalls.
    This sounds like the tool short-circuits the house voltage.



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    Re: Trying to repair a Bosch JS470E jigsaw - component ID?

    I would agree with Brad that it sounds a bit more serious than a broken inductor.

    However, answering your original question, it does appear to be a 4.7mH inductor (aka a 'choke'). Basically a small ferrite core with lots of turns of wire around it. Its purpose would be to convert some of the magnetic field from the motor back into a voltage so it can be sensed on the main board. The controller will be capable of varying the power to the motor to adjust the speed but it also needs some feedback to tell whether it has been successful or if the motor has stalled/jammed. Without the inductor it is possible it just fires full power at the motor in the belief it needs more to get it turning because the sensor isn't returning any signal.

    If you do a search for "4.7mH choke" you should find an alternative part. The value is important and it should be an axial type (wire out at each end) but otherwise the make and size probably are not critical. Try to find one looking similar if possible but avoid anything that is surface mounted (SMD) or has a core looking like a cylindrical watch battery as their construction is designed NOT to pick up external fields.

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    Re: Trying to repair a Bosch JS470E jigsaw - component ID?

    Awesome, I really appreciate the info from both you.

    Worst case I buy a new saw, but am hoping this works since I gambled initially buying a saw with a faulty switch in the first place (75% off).
    As luck would have it, repairing the switch was simple, but I seem to have made things worse in the process.
    Way she goes. Live and learn, at least I gained some insight into the components.

    Thanks,

    Zach



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    Re: Trying to repair a Bosch JS470E jigsaw - component ID?

    Hi,

    maybe something like this:
    https://at.rs-online.com/web/p/induk...ahtet/1911197/

    maybe in the rotating plate (cooling fan) there is a magnet that generates some voltage when passing the inductor to get RPM information.

    Klaus
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    Re: Trying to repair a Bosch JS470E jigsaw - component ID?

    I haven't seen, yet, that Bosch uses inductor for sensing rotation of the motor in hand tools.
    Hall sensor, yes.
    Magnet on the fan would disballance (by mass) the fan, an it is only a plastic injection molded part.
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