Brother LK3-B430E Mark II Service Manual page 89

Error status Probable causes
#1 4. Fuse has blown
The
power
lamp
does not
light
when the
power is
turned on.
5. Power supply circuit board
defective
6. Main circuit board defective
P9
7. Panel circuit board defective
Check/repair/adjust
a. Remove fuses No.3 and No.4, and check
them for continuity.
If there is no continuity, replace the fuses
with new ones, and perform the check/
repair/adjust items of #1-5.
a. Separate P4 (ACIN) connectors on the
power supply circuit board, and then
measure the resistance between the
following pairs of pins, pins 1 and 4 and
pins 2 and 4, in the connector on the
cable.
If the resistance is ∞Ω in both cases, the
power supply circuit board is not
defective.
b. Measure the resistance between pins 1
and 2.
If there is no short, the power supply
circuit board is not defective.
c. Rejoin P4 (ACIN) connectors on the
power supply circuit board.
Separate P9 (POWER) connectors on the
main circuit board, turn on the power,
and measure the voltage across pins 1
and 3 in the connector on the cable.
If it is + 5V, the power circuit board is not
defective.
After measurement, turn off the power,
wait at least 5 minutes, and then rejoin
P9 connectors.
With P9 (POWER) connectors plugged in on
the main circuit board, turn on the power, and
measure the voltage across pins 1 and 3 in
the connector on the cable.
If it is + 5V, the power circuit board is not
defective.
After measurement, turn off the power.
Check that P8 (PANEL) connectors of the main
circuit board and P1 (PANEL) connectors of
the panel circuit board are plugged in.
LK3-B430E Mark II
10. ELECTRIC MECHANISM
Parts to be replaced
Fuse 6A-250V
Power supply
circuit board
Main circuit board
Panel circuit board
panel cord
82