Brother MP-21C Service Manual page 105

(2) No DC power generated
Possible Step
cause
AC power 1
supply
Power 2
supply
FFC
Power 3
supply unit
Check
Is DC power supplied between the
DC jack (+ / -)when the power plug is
plugged into the outlet?
Is the Power supply FFC cable
connected to the Main PCB ASSY
and the Power supply PCB ASSY?
Measure the voltage between the
terminals. Do the measured
voltages satisfy the value in the table
below?
PCB + lead - lead
Driver P3-9 P3-10
PCB P3-8 P3-10
P3-17 P3-15
P3-18* P3-15
* The voltage for P3-18 depends on
the operating temperature.
IV-4
Result
NO
NO
NO
Voltage
+3.3V
+5V
+12V
+13 - 30V
Remedy
Follow the same check
procedure of 1) "No DC
power supplied from
PCMCIA" and "No AC
power supplied from the
AC adapter".
Connect it to the both
PCBs securely.
Replace the power
supply unit.