Brother BAS-311G service manual Electrical Mechanism

8. ELECTRICAL MECHANISM

Problem #17 Intermittent presser foot does not drop during sewing.

Cause		Inspection/Remedy/Adjustment	Replacement if a malfunction
2. If the presser foot does not	1)	Disconnect connector P9 (POWER1) from	PMD P.C. board, or power
operate and [E300] is displayed,		the PMD P.C. board and measure the	supply motor P.C. board
there is a malfunction of the		resistance between pins 1-2 at connector P9.
PMD P.C. board or of the power		OK if ∞ Ω; if 0 Ω, there is a malfunction of
supply motor P.C. board.		the PMD P.C. board.
	2)	Measure the resistance between the fuse F2
		terminal that is close to P6 (MAIN) and pin 2
		of connector P7 (PMD) on the power supply
		motor P.C. board. (D10 check)
		OK if ∞ Ω
	3)	Disconnect connector P9 (POWER1) from
		the PMD P.C. board, and then measure the
		voltage between pins 1-2 of the cord-side
		connector.
		OK if approx. +100 V
		After measuring, turn off the power, wait 5
		minutes or more and then insert P9.
	4)	Disconnect connector P2 (POWER2) from
		the PMD P.C. board, and then measure the
		voltage between pins 1-2 of the cord-side
		connector.
		OK if approx. +16 V
		After measuring, turn off the power, wait 5
		minutes or more and then insert P2.
	5)	Check that connector P1 (MAIN) is inserted
		into the PMD P.C. board.
4884Q
3. If the presser foot moves slightly	1)	Check that connector P5 (P-ENC) is inserted	Pulse motor P assembly
and then [E300] is displayed,		into the main P.C. board.
there is a malfunction of the	2)	Check the encoder input while referring to
encoder.		“2-8. Input checking method”.
4. If the presser foot operates and	1)	Check that connector P8 (SENSOR1) is	Work clamp home position
[E300] is displayed, there is a		inserted into the main P.C. board.	sensor
malfunction of the work clamp	2)	Check the work clamp home position sensor
home position sensor.		input while referring to “2-8. Input checking
		method”.
	3)	If a metallic object is brought close to the
		work clamp home position sensor and the
		LED inside the sensor does not illuminate,
		there is a malfunction of the sensor.
	4)	If it illuminates, the home position dog is
		incorrectly adjusted.
		Switch to home position adjustment mode,
		and adjust the position of the home position
		dog. Refer to “7-20. Adjusting the home
		position”.

132 BAS-311G, BAS-326G