How to fix cheap dogs hair clipper

Today is the day I almost forgot I'm a maker.

Say hello to a beloved family member - Mufasa!
This is Mufasa

Mufasa is a Maltese, his hair needs to be trimmed once in a while.
Instead of paying tons of money to a professional dog barber, I've bought a dogs hair clipper on Amazon a couple of years back, and since then I trim his hair - It's quite a bonding experience, to be honest :)

Today the trimmer life came to an end.

It has been like 15 minutes since the death of my hair trimmer, and I already had 20 tabs in chrome directing to different online shops, with a variance of dogs trimming machines. Since it's have been a while from my last post: installing-ros-docker-with-gpu-support-for-controlling-djis-tello-drone. I simply forgot to ask the most motivating question a man can ask:

I wonder what could have gone wrong with my machine?

At that exact moment, It was as if I woke up from a dream. And remembered that I'm a maker, and it is a riddle that needed to be solved!

So I dove right in..

At first glance, I saw that there were some components that were covered with corrosion (Like C1, in the top left curner)

Corrosion means that there's humidity, but that's obvious - I used to clean the clipper under a stream of water after every usage.

Sadly, I saw the DONT WASH UNDER TAP sign too late (two years too late)

First attempt - cleaning the corrosion.
Doing so didn't help much. Still, no response when turning on the machine.

I had a gut feeling for a bad battery - It did supply 3.3v so I tried to connect the battery with reverse polarity - And behold - It worked!

The second attempt - Figuring out why it works with reverse polarity?
To do so, I looked at the MOSFET:

Luckily, I know what MOSFET is due to a post I made in the past: adding-iot-capabilities-to-an-old-automatic-watering-system. And what I've learned is that in MOSFET the current flows from Drain to Source, and the Gate can change its conductivity - meaning control the current amount from Drain -> Source:

Where in the trimming machine circuit, all the MOSFET's right pins are the D's, and that the current goes from the motors +, to the D's and from them to the S1 & S2.

So as for a quick&dirty fix, I soldered S1 and D1 together, so the MOSFET is actually being bypassed:

And where back in biz!

Wrap up

Today I almost forgot I'm a maker, and it could have cost me 40$ + 3-5 weeks of shipment. Luckily, my inner self woke me up with this innocent question:
I wonder what could have gone wrong?

It's important to have a passion in life, for me it is making new, enhance the existing, and fix the broken. for you?

Food for thought.

Til next time,
Cheers Gal.


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