Brother BAS-311E Service Manual page 115

Error status Probable causes
4. Power PCB defective.
Work clamp for pneumatic specification (BAS-311E and 325E)
#4
The work
clamp does 5. The air valve is defective.
not move
up and
down
when the
foot switch
is stepped
on.
6. The control circuit board (#3) is
defective.
Check/repair/adjust
• Measure the resistance between a terminal in the
center of the power PCB and pin 2 in connector P5
(DC300).
The resistance should be
• Remove connector P12 (POWER) on the control
circuit board, turn on the power, and measure the
voltage across pins 4 and 6, pins 5 and 6, pins 5
and 7 on the cord.
The voltage in each case should be +55V.
Measure the voltage across pins 2 and 3. The
voltage should be +20V to 24V.
After measurement, turn off the power, wait at
least 5 minutes, and insert P12.
• Pull out connector P4 (AIR) on the control circuit
board and measure the resistance between the
following pins in the connector on the cord:
Pins 1 and 10 (air valve for right work clamp)
Pins 2 and 10 (air valve for left work clamp)
Pins 3 and 10 (air valve for presser foot; only
for optional specification)
The resistance in each case should be 300 - 400
• Pull out connector P4 (AIR) and measure the
voltage across the following pins in the connector
on the PCB:
Pins 1 and 10 (air valve for right work clamp)
Pins 2 and 10 (air valve for left work clamp)
Pins 3 and 10 (air valve for presser foot; only
for optional specification)
The voltage in each case should be +20V to 24V.
After measurement, turn off the power, wait at
least 5 minutes, and insert P4.
BAS-311E.311EL.326E.326EL
Chapter 7
Parts to be replaced
Power PCB
Air valve
Valve harness assy.
Control circuit
board.
107