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Brother PT-E300 Industrial Label Machine Teardown

Tape Installed
Tape Installed

Here a tape is installed in the printer. This unit can handle tape widths up to 18mm. The pinch rollers are operated by the white lever at the top of the image, which engages with the back cover.

Li-Ion Battery
Li-Ion Battery

This printer is supplied with a rechargeable battery pack, but AA cells can be used as well. Some of the AA battery terminals can be seen above the battery.

Battery Specs
Battery Specs

Pretty standard fare for a 2-cell lithium pack. The charging circuitry doesn’t appear to charge it to full voltage though, most likely to get the most life from the pack.

Cartridge Slot
Cartridge Slot

With the cartridge removed, the printer components can be seen. As these cartridges have in effect two rolls, one fro the ribbon & one for the actual label, there are two drive points.

Pinch Rollers & Print Head
Pinch Rollers & Print Head

The thermal print head is hidden on the other side of the steel heatsink, while the pinch rollers are on the top right. The plastic piece above the print head heatsink has a matrix of switches that engage with holes in the top of the label cartridge, this is how the machine knows what size of ribbon is fitted.

Mainboard
Mainboard

Most of the internal space is taken up by the main board, with the microprocessor & it’s program flash ROM top & centre.

Charger Input
Charger Input

The charger input is located on the keyboard PCB just under the mainboard, which is centre negative, as opposed to 99% of other devices using centre positive, the bastards.

LCD Module
LCD Module

The dot-matrix LCD is attached to the mainboard with a short flex cable, and from the few connections, this is probably SPI or I²C.

Print Mech Drive
Print Mech Drive

The printer itself is driven by a simple DC motor, speed is regulated by a pair of photo-interrupters forming an encoder on the second gear in the train.

Battery Holder Connections
Battery Holder Connections

The back case has the battery connections for both the lithium pack & the AA cells, the lithium pack has a 3rd connection, probably for temperature sensing.

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Fire Angel CO-9D Carbon Monoxide Detector Teardown

Fire Angel CO-9D CO Detector
Fire Angel CO-9D CO Detector

This detector has now been retired from service since it’s a fair bit out of date. So here’s the teardown!

Information
Information

Unlike older detectors, this unit has a built in battery that never needs replacing during the life of the sensor, so once the unit reaches it’s expiry date it’s just trashed as a whole.

Cover Removed
Cover Removed

4 screws hold the cover on, here’s the internals of the detector. There’s a 3v CR123A LiMnO² cell at the right for power, rated at 1500mAh. A 7 year life is quite remarkable on a single cell!
The sensor is just to the left of the lithium cell, and is of quite unusual construction. Previous CO sensor cells I’ve seen have been small cylinders with a pair of brass pins. This one appears to use a conductive plastic as the connections. These sensors contain H²SO⁴ so they’re a bit hazardous to open.
There are no manufacturer markings on the sensor & I’ve not been able to find any similarly shaped devices, so I’m unsure of it’s specifications.
The alarm sounder is on the left, the usual Piezo disc with a resonator to increase the loudness.

Microcontroller
Microcontroller

The brains of the device are provided by a Microchip PIC16F914 microcontroller. This is a fairly advanced device, with many onboard features, and NanoWatt™ technology, standby power consumption is <100nA according to Microchip’s Datasheet. This would explain the incredible battery life.
The choke just at the right edge of the photo is actually a transformer to drive the Piezo sounder at high voltage.

PCB Reverse
PCB Reverse

Here’s the PCB with the LCD frame removed. Not much to see on the this side, the silence/test button top right & the front end for the sensor.

Sensor Front End Amplifier
Sensor Front End Amplifier

Here’s a closer look at the front end for the CO sensor cell itself. I haven’t been able to decode the SMT markings on the SOT packages, but I’m guessing that there’s a pair of OpAmps & a voltage reference.

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Maplin LED Torch Charger Replacement

In my previous post, I mentioned I’d be replacing the factory supplied charging gear with something that actually charges lithium chemistry cells correctly.

Charging Base
Charging Base

Here’s the base as supplied, with an indicator LED on the right hand side. This LED indicates nothing other than power being applied to the charging base. It’s just connected across the power input with a resistor. This also means that any battery left in the charger while it’s unplugged will discharge itself through this LED over time. Great design there China!

PCB Removed
PCB Removed

Here I’ve removed the PCB – there’s no need for it to be taking up any space, as it’s just a complete waste of copper clad board in the first place. The battery tabs have been desoldered & hot snot used to secure them into the plastic casing.

USB Hole
USB Hole

The charger modules I use are USB powered, so a small hole has been routed out in the casing to allow access to the port.

Charging Module
Charging Module

Here the charging module has been installed & wired to the battery tabs. Output is now a nice 4.18v, and will automatically stop charging when the cell is full.
Safety has been restored!

73s for now folks!