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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.