Brother PS-300B Owner's Manual

BAS-311E.311EL.326E.326EL

#1 

continued

 Probable causes

4. Fuse has blown 

5. Power supply circuit board 
 defective

6. Control circuit board defective

7. Panel circuit board defective

 Check/repair/adjust

• Remove fuses No.3 and No.4, and check them for 

continuity.
If there is no continuity, replace the fuses with new 
ones, and perform the check/repair/adjust items of 
#1-5. 

• Separate P4 (ACIN) connectors on the power supply 

circuit board, and then measure the resistance 
between the followin

 oth cases, the power supply 

circuit board is not defective.

• Measure the resistance between pins 1 and 2.

If there is not short, the power supply circuit board is 
not defective.

• rejoin P4 (ACIN) connectors on the power supply 

circuit board.
Separate P3 (POWER) connectors on the main circuit 
board, turn on the power, and measure the voltage 
across pins 1 and 3 in the connector on the cable.
If it is + 5V, the power circuit board is not defective.
After measurement, turn off the power wait at least 5 
minutes, and then rejoin P3 connectors.

• With P3 (POWER) connectors plugged in on the 

control circuit board, turn on the power, and measure 
the voltage across pins 1 and 3 in the connector on 
the cable.
If it is + 5V, the power circuit board is not defective.
After measurement, turn off the power.

• Check that P18 (PANEL) connectors of the main circuit 

board and P5 (DRV) connectors of the panel circuit 
board are plugged in.

Parts to be replaced

Fuse 6A-250A

Power supply 
circuit board

Control circuit 
board

Panel circuit board

Error status