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Brother P-Touch Labeller not powering up

partyanimallighting

Oct 22, 2012
330
Joined
Oct 22, 2012
Messages
330
Hi Wizards!

I have a Brother labeller that died on me and I would really like to get it functional again. I've opened up the unit but I am in no way knowledgeable about how these units work. The unit receives 12VDC power from a wall wart and I am receiving 12VDC coming into the main PCB from the power PCB at the input terminal (blue / orange wires). However, there is another 4 wire input (green / red / white / black) and I'm not getting any DC voltage at this terminal. I'm not sure where to start here as I am very unfamiliar with this type of unit and I'm wondering if this terminal receives 12VDC directly or if it is triggered via the USB input from the PC. Any ideas?20181024_005429.jpg 20181024_005456.jpg
 

kellys_eye

Jun 25, 2010
4,775
Joined
Jun 25, 2010
Messages
4,775
The USB port is likely to be totally independent of the power input socket and feed to the main board but you can easily check this by looking at the pcb traces under the wires going to it.
 

73's de Edd

Aug 21, 2015
3,365
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Aug 21, 2015
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3,365
Sir partyanimallighting . . . . . .

Here is being the power flow within that power connector PCB.

***** The F1 fuse only relates to battery operation circuitry, it is out of circuit in AC power operation. *****

BATTERY . . . . .operation . . . . .
At the top is the unit just running on battery cells, with the RED and BLACK squares showing that the battery plus routes thru the fuse and loops thru two connections of the barrel connectors jack and ends up at the ORANGE wire.

POWER ADAPTER . . . . .operation . . . . .
The J1 pin receives the adapters negative voltage input and it flows straight thru to the GND- BLACK and BLUE connections.
The presence of the barrel connector plug opens any connection to the battery while the connector is plugged in and routes the battery plus voltage straight thru to the ORANGE wire.

At zero extra charge to you, the GREEN path sends back a trickle charge for the battery pack, as long as the power adapter is plugged in.

Now use this info and metering to find your problem source.

Possibilities . . . . .
The connectors internal switch has loosened up with use OR it has been wiggled so much that possibly floating solder joints have developed from its solder connections to the PCB .

FIO there is a regulator IC that the DC power passes thru before reaching the feed motor, compensating for declining battery power, if so used.

ALSO . . . . .the USB connector is strictly being for digital handshaking, if so used.

Thassssssssit . . .

UNITS TECHNO REFERENCE . . of. . . BROTHER PT-1800-1900 SERIES Power Supply Section



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73's de Edd
.....
 
Last edited:

partyanimallighting

Oct 22, 2012
330
Joined
Oct 22, 2012
Messages
330
Hi all, just did some testing and the voltage input into the main PCB terminal with the blue/orange wires is fine at 12VDC from the wall wart through the voltage PCB so I think that would rule out the voltage input PCB so it's looking like an issue with the main PCB so I'm going to tray a little further disassembling to try to get to the other side of the main PCB.
 
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