The Power Does Not Come On - Brother NV4000D Service Manual

Failure Investigation for Electronic Parts The power does not come on
When the power is turned on,
nothing appears on the LCD.
When the power is turned on, does
the buzzer sound after a while?
Is the power supply cord free from
damage and connected correctly?
Is the inlet assembly (D6) free from damage
and correctly connected to the power PCB?
Is lead wire A on the main panel free from
damage and correctly connected to the
main PCB (CN17) and panel PCB (CN1)?
Is lead wire B on the main panel free from
damage and correctly connected to the
main PCB (CN12) and panel PCB (CN3)?
When the power PCB connector (main PCB
(CN13)) is disconnected, are the voltages
between pins 5 & 6 and pins 8 & 6 normal?
Between pins 5 & 6: 4.75 - 5.25 V DC
Between pins 8 & 6: 24.7 - 27.3 V DC
When lead wires A and B on the main panel are
removed from the main PCB and power is turned on in
the "no-front-cover test" mode, does the buzzer sound?
N
Y
Y
Y
Y
Y
Y
Replace the power PCB.
Y
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N
Connect the power supply
cord correctly or replace it.
N
Connect the inlet assembly
(D6) correctly or replace it.
N
Connect lead wire A on the main
panel correctly or replace it.
N
Connect lead wire B on the main
panel correctly or replace it.
N
Replace the power supply
unit (D6).
N
Replace the power supply
unit (D6).
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