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Typical microwave electrical fault

APACHEBCN 17 APRIL 2020

The dirty trick in microwaves

This breakdown is as typical and as popular as April Fools' Day.

Who has not ever gone off the light when turning on the microwave?
How many of us have not discarded our not-so-old microwave thinking it was a major malfunction?

I am going to tell you briefly what this fault is about, that it is nothing more than a totally intentional bad design and that it has not progressed over many years.

What is the fault in which the microwave makes the light jump

All microwaves have as a design in the closing and opening of the door the use of hooks.
As you can easily guess, all these hooks move to grip and release themselves from the microwave chassis, aided by springs. (similar to what a conventional door mechanism does)
And if you have noticed, all doors have 2 hooks.

Some microwaves have these hooks in different sizes and shapes, but they all have hooks, and there are almost always 2.
The microwaves that have 2 hooks, are the ones that are using this stupid and absurd trick, which causes the spark and cancels the electrical supply of the house or establishment.

When we open and close the microwave door, each of these hooks press and release its respective button.
Sometimes one of these hooks has more than one push button.

But in addition to managing several separate circuits, they also deliberately open and close contacts that come directly from the current.
Mounted in such a way that if any of the hooks is late to press its button, a totally deliberate short circuit is exerted.

The reason for this planned and conscientiously consented breakdown
People who understand and live by this defend this design claiming that it is for security reasons.
Safety refers to not allowing the magnetron to operate with the user in front with the door open.

But with this we have to assume that our electrical installation is in the right conditions to withstand a capricious short circuit.

It seems to me personally as wild as if my car were to blow a wheel when exceeding speed, and the manufacturer told me that this is better than having an accident.
All users who are looking for information about which fault in their microwave causes the light to jump, this is it. A deliberate and planned short circuit from the day of its manufacture.

Solution to this fault

There is no standard and elegant solution for this, other than to undergo the obligatory replacement of the hooks.
And with the consequent expense and that will be a start over with the same plan.
It is also a delicate and forced operation, which does not always leave the door in perfect condition.

You can also convert this system, disassembling everything and removing all the hooks.
Making a single button activate several relays (all necessary according to the circuits to be managed)
That is, when opening and closing the door, 2 or 3 relays are managing those circuits at the same time.
The supposed risk of having your head close to the magnetron unconsciously is quite unlikely, plus we would notice other things, such as spinning fans, magnetron noises and etc.
Rarely is a relay going to fail in the short term, and very rarely 2 or 3 relays will one fail causing the strange consequence of the magnetron operating with the door open and out of the electronic program of the microwave panel.

What I did was design a magnetic closure, where the magnet attracts the door and keeps it closed, and the door presses a fairly light push button.
And this button activates and deactivates 2 relays simultaneously.

Disassembled microwave door

 

This is the relay I have used (it's 2 relays in one):

Ttl relay to replace the microwave hook system

 

This is how the microwave chassis looks.
Here in the holes you could see some plastic that served as a ramp for the hook to go up as it was introduced.
Now you can see a normal button in the hole above, and in the hole below there is nothing now.

Microwave without hooks with standard push button

 

And so the microwave door is finally left.
Several neomidium magnets are installed inside the door.
They are not seen because they are inside.
And with adhesive tape I have glued the holes that were for the hook support.

Hookless microwave with neodymium magnets

 

If you prefer to see it more detailed in a video, you can do it with this youtube:

Autor:  Pedro Reina Rojas
Más de 20 años de experiencia en programación.
Programador PHP Senior BackEnd. (un poquito fullstack a veces)
Programador Django.
Programación por ocio con Arduino y rasperry Pico.