8. ELECTRICAL MECHANISM - Page 139

8. ELECTRICAL MECHANISM 

132

BAS-311G, BAS-326G

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 

operate and [E300] is displayed, 
there is a malfunction of the 
PMD P.C. board or of the power 
supply motor P.C. board. 

1) Disconnect connector P9 (POWER1) from 

the PMD P.C. board and measure the 
resistance between pins 1-2 at connector P9. 
OK if 

∞ Ω

; if 0 

Ω

, there is a malfunction of 

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. 

PMD P.C. board, or power 
supply motor P.C. board 

3.  If the presser foot moves slightly 

and then [E300] is displayed, 
there is a malfunction of the 
encoder. 

1) Check that connector P5 (P-ENC) is inserted 

into the main P.C. board. 

2)  Check the encoder input while referring to 

“2-8. Input checking method”. 

Pulse motor P assembly 

4.  If the presser foot operates and 

[E300] is displayed, there is a 
malfunction of the work clamp 
home position sensor. 

1) Check that connector P8 (SENSOR1) is 

inserted into the main P.C. board. 

2)  Check the work clamp 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”. 

Work clamp home position 
sensor 

4884Q