A Wahl 'Peanut' Hair Clipper Failure

Someone brought me an inoperative Wahl 'Peanut' hair clipper. Here's a view of it without its cutter head.

And here's the underside.

Three No. 0 Phillips recess screws fasten the unit together. Here it is opened up.

(That photo was taken after I'd done some unsoldering.)

There's not much to the thing -- a DC motor, a bridge rectifier, an inductor^[1] and a slide on/off switch that's incorporated into the printed circuit board. Here's the schematic.

The unit had suffered a catastrophic failure of the bridge rectifier and the inductor. The two '+ side' diodes in the rectifier were dead shorts, and the inductor had blown up. Here's what was left of the inductor after unsoldering it from the circuit board.

The motor survived. Here's a brief video of the motor running with a jury-rigged rectifier.

The '32 mA' figure printed on the motor must be a full-load value. Running without the clipper head attached and no loading, the motor draws about 7 mA. Motor speed is about 10,200 rpm. Loading the motor with finger pressure results in a large increase in motor current, and a corresponding reduction in motor speed.

I've ordered replacement 2W10 bridge rectifiers from Amazon. The 2W10 is a little more robust than the original W04M.

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The Rectifiers Arrived -- THURSDAY, JANUARY 10, 2019

The 2W10 is physically identical to the W04M.

Here's the circuit board set up for soldering in the new rectifier and inductor.

And the little machine went back together and is working. I can return the unit to its owner for a proper trial with the cutter head attached.

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Note:

[1] From what's left of the colour code bands, the inductor appears to be 150µH. Fortunately, I have spares on hand that I got from Amazon long ago.

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