The Power Does Not Come On - Baby Lock BLSY 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 free from damage and
correctly connected to the power PCB?
When the power PCB connector (main PCB
(CN5)) 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
Replace the SS PCB.
Y
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N
Connect the power supply
cord correctly or replace it.
N
Connect the inlet assembly
correctly or replace it.
N
Replace the power supply
unit.
N
Replace the main
assembly.
PCB
5 - 3