# Introduction

Although classified as an "accessory," the LG AN-MR19BA infrared magic TV remote is an indispensable part of the LG Smart TV system. Without the magic remote, it is safe to say most of the basic features of the Smart TV are not available to the user. It is like losing both arms and legs.

# The Wheel Button of the Magic Remote

Central to menu selection and activation is the wheel in the middle of the magic remote. Ostensibly similar to mouse wheels, it functions as a button, with a similar feel as the middle button of a mouse.

Although most mouse wheels utilizes photo-interrupters to detect mouse wheel rotations, the LG magic remote implements the wheel feature with a potentiometer. This means the wheel axle must be inserted into the potentiometer in order to turn it. The axle has a hexagonal cross section to assure a positive grip on the potentiometer.

The wheel is also a button, to activate menu selections. When the user presses on the wheel, the part of the axle opposite from the potentiometer presses down on a PCB button. Of course, the hexagonal axle must flex in order for the button to be depressed. That's a substantial load on a very tiny cross section, and it may possibly give way after a number of cycles.

# The Wheel Button of the Magic Remote

If your wheel button axle should break, what would be the dimensions to machine a new axle?

A new axle can be machined out of a 2mm OD stainless steel rod. Each side of the hexagon turns out to be 1mm long.

So the amount to cut into the rod on each side of the hexagon is:

$1-\frac{\sqrt{3}}{2}$ mm

Last updated on 22 Jun 2021