3 ] Led Does Not Turn On; Led Doe Not Turn On. - Brother P-touch QL-1050 Service Manual

[ 3 ] LED does not turn on.

LED does not turn on.
Or LED turns on temporarily.
Is the cable of SB PCB
connected correctly?
lines in the cable broken?
Is the panel cover
assembled correctly?
Is the head cable of
the correct color connected?
Is the head cable
connected correctly?
(CN12)connected to the
power supply PCB correctly?
Are the power supply PCB, DC8V
power PCB and main PCB
connected correctly?
Is the connector output
of the power supply PCB 24 to 26V?
Is the output of the pin (No.1)
on the power supply
output of the DC8V power
Are the key and LED
signals of CN15 normal?
Are the output signals
from Pin 3 and Pin 4 of
The SB PCB is defective.
Replace the SB PCB.
N
Y
Y
Are any of the
N
N
Y
Y
Is the connector
Y
PCB 7 to 10V?
Y
Is the connector
N
PCB 7 to 10V?
Y
N
Y
N
CN15 normal?
Y
IV- 5
Correct the connection.
Replace the SB PCB.
Re-assemble the cover correctly.
N
Correct the connection.
N
Correct the connection.
N
Replace the power supply PCB.
Replace the DC8V power PCB.
Replace the SB PCB.
Replace the main PCB ASSY.