The victim of my teardown is a treadmill monitor. It has push buttons and an LCD panel on the front side. On the backside, it has a metal piece to hook onto a treadmill and a lidded slot for two AA batteries.
The outer carcass of the monitor is held together by a small handful of screws that are easily visible on the backside. Though rusty, these were easy to remove.
On the inside, a large circuit board with myriad parts is firmly attached to the bottom of the carcass with small screws. These took effort to remove. The push buttons however, popped right off.
It was surprising that the screen was taped onto the carcass with mere tape! You could definitely tell how old this item was from that yellowed color….
A- Always B-be K-Knolling (if you don’t get it see this)
The circuit board – technically a Printed circuit board (PCB), is made of a series non-conductive material layers (like fiberglass) that conceal copper circuits that run along the board. Most copper circuits are protected by a thin green laminate (which can easily be scratched off!) that superficially illustrates where the copper wires lie. Some copper circuits however, are revealed, like in the case of the push-buttons and the LCD screen. Here is a cool PCB breakdown by layers graphic that I found.
PCB boards are manufactured in factories by a series of cutting machines, drilling robots, edge-polishing machines, plating the with boards copper, printing the circuit diagrams on the boards, and so on and so forth. This video shows the complete process.
LDC screen – is made of liquid crystal material, which I don’t really know what it means, but it looks like it is made of a series of glass and other very thin sheets of polarized film and films with electrodes.
The encasing – the rigid plastic enclosure that protects and keeps in place all the electronic parts of the monitor, as well as the buttons and batteries. Likely injection-molded in a factory.
The buttons – made out of hard plastic and rubber, the buttons are injection molded, then the inscriptions on them are (probably) UV printed by machines.
Back To the Board
On the monitor’s PCB board are the following:
- One TC4069UB Hex Inverter, which is responsible of inverting the signal received (if IN is LOW, then OUT is HIGH; of if IN is TRUE then OUT is FALSE)
- One LM324N operational amplifier which responds to a small input signal and produces a larger output with the same characteristics as the input.
- Plenty of resistors (R) of different line colors. Resistors are used to reduce current flow.
- Several 104 round ceramic capacitors (C), as well as larger cylindrical capacitors. Capacitors store electrical energy.
- Diodes (D). Diodes act as one-way-switches for current, meaning that it enables a current to flow in one direction, but prevents it to flow in the other.
- Connector Jacks (J). Connector jacks are used to connect sub-sections of a circuit together.
- Transistors (Q). Which look like short cylinders out of which a slice has been taken off. Transistors are responsible for regulating current, of for amplifying a signal into an even greater signal.
- Switches (S) (apparently, though they don’t look like it). Switches are responsible
- Meters (M). Meters measure the currents and voltages in a circuit without changing them.
Other terminology that I looked up:
- Blowers/motors (B)
- Terminals (E)
List of Tools and Techniques for Teardown
-Large screw driver star bit to detach the monitor mount from the monitor
-Medium screw driver star bit to open the monitor encasing
-Small screw driver star bit to internally dismount the circuit board from the monitor’s encasing.
-Snippets to cut the wires joining the circuit to the speaker.
My Favorite Design Elements
- The revealed copper circuitry int he areas where the buttons and LCD screen are touching the circuit board. It is elegant and I like the bit of reveal.
- The push-buttons, starting with the fact that the markings on them are still intact. This means the designers really considered the fact that users would be sweating, and selected the most lasting printing method.
Questions for Becky:
On the board, there are some components that look like one thing, but the markings label them as another thing. For example, I see what looks like a transistors that is marked as E B C on the board. I’m confused about why that is.