Brother RH-9820 Service Manual page 227

Problem #14 Lower thread trimming does not operate.
Cause
Malfunction of valve or valve harness
Problem #15 Hammer does not operate (when set to cutting after sewing).
Cause
Malfunction of valve or valve harness
Inspection/Remedy/Adjustment
Check that connector P12 (AIR1) is inserted
into the main P.C. board.
Inspection/Remedy/Adjustment
Check that connector P25 (AIR2) is inserted
into the main P.C. board.
RH-9820
8. ELECTRICAL MECHANISM
Replacement if a malfunction
Valve harness
Replacement if a malfunction
Valve harness
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