8. ELECTRICAL MECHANISM - Page 140

8. ELECTRICAL MECHANISM 

133

BAS-311G, BAS-326G

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

Cause

Inspection/Remedy/Adjustment

Replacement if a malfunction

5. If the presser foot does not 

move and [E300] is displayed, 
there is a malfunction of the 
pulse motor or cord. 

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. 

Pulse motor P assembly 
 
 
 
 
 
PMD P.C. board 

Problem    # 18    Sewing machine does not operate during sewing and [E120] is displayed. 

Cause

Inspection/Remedy/Adjustment

Replacement if a malfunction

1. Malfunction of sewing machine 

motor cord 

Check connector P4 (UVW) of the power supply 
motor P.C. board and the sewing machine motor 
connector. 

Motor cable 

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. 

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. 

Power supply motor P.C. 
board 

3.  Sewing machine motor overheats 

and the thermostat inside the 
motor operates when the sewing 
machine is operated at short 
cycle. 

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. 

Motor cable 

4888Q