Brother RH-9820 Service Manual page 225

Problem #8 Work clamp is not lowered during sewing.
Cause
Malfunction of valve or valve harness
Problem #9 Hammer does not operate (When set to cutting before sewing).
Cause
Malfunction of valve or valve harness
Problem # 10 Sewing machine does not operate during sewing and [E120] is displayed.
Cause
1. Malfunction of sewing
motor cord
2. If the fuse (F1) on the power supply
motor P.C. board is 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) Check that connector P12 (AIR1) is
inserted into the main P.C. board.
2) Check the air.
Inspection/Remedy/Adjustment
Check that connector P25 (AIR2) is inserted
into the main P.C. board.
Inspection/Remedy/Adjustment
machine 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 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 or more.
2) Turn the power back on; OK if operation is
normal.
Avoid repeated sewing of sewing data that is
less than 15 stitches.
RH-9820
8. ELECTRICAL MECHANISM
Replacement if a malfunction
Valve harness
Replacement if a malfunction
Valve harness
Replacement if a malfunction
Motor cable
Power supply motor P.C.
board
Motor cable
216