Brother BAS-326G Service Manual page 140

Problem #17 Intermittent presser foot does not drop during sewing.
Cause
5. If the presser foot does not
move and [E300] is displayed,
there is a malfunction of the
pulse motor or cord.
Problem # 18 Sewing machine does not operate during sewing and [E120] is displayed.
Cause
1. Malfunction of sewing machine
motor cord
2. If the fuse (F1) on the power
supply motor P.C.
blown, there is a malfunction of
the main P.C. board.
3. Sewing machine motor overheats
and the thermostat inside the
motor operates when the sewing
machine is operated at short
cycle.
Inspection/Remedy/Adjustment
1) Disconnect connector P3 (PPM) from the
PMD P.C. board, and measure the resistance
between pins 1-2 and 3-4 at the cord-side
connector.
OK if 2-3 Ω
After measuring, insert P3.
2) If 1) is OK, there is a malfunction of the PMD
P.C. board.
4888Q
Inspection/Remedy/Adjustment
Check connector P4 (UVW) of the power supply
motor P.C. board and the sewing machine motor
connector.
1) If the fuse (F1) is blown, check the resistance
board is values between all pins of the connector P4
(UVW) and the pins of the fuse (∞ Ω) and
replace the fuse.
2) If the fuse blows again, replace the power
supply motor P.C. board.
1) Turn off the power and let the sewing
machine stand for 30 minutes.
2) Turn the power back on; OK if operation is
normal.
Avoid repeated sewing of sewing data that is
less than 15 stitches.
BAS-311G, BAS-326G
8. ELECTRICAL MECHANISM
Replacement if a malfunction
Pulse motor P assembly
PMD P.C. board
Replacement if a malfunction
Motor cable
Power supply motor
board
Motor cable
P.C.
133