Led Light Does Not Turn On - Brother PR600II Service Manual

Failure Investigation for Electronic Parts LED light does not turn ON.
Is the LED light assembly properly
connected to CN1 on the LED drive
PCB?
Is the LED drive PCB properly
connected to CN9 on the main
PCB?
Does the LED light turn ON when
the LED drive PCB is replaced with
another one?
Does the LED light turn ON when
the LED light assembly is replaced
with another one?

LED light does not turn ON.

Y
Y
N
Y
Change main PCB.
N
Connect LED drive PCB and
LED light assembly properly.
N
Connect main PCB and LED
drive PCB properly.
Y
Change LED drive PCB.
N
Change LED light assembly.
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