Brother International MD-817 Service Manual - Page 37
Troubleshooting
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TROUBLESHOOTING * When troubleshooting is required, separately inspect such main parts as the control box, motor, operation panel box, motor, operation panel box, synchronizer, power switch, machine solenoid and presser foot lifter. • When the control box is found to be out of order, inspect the control circuit board, power board, treadle unit, and transformer separately. • Whatever trouble you encounter, check that the connectors are secure. * Pay extra attention to the maintenance of the power and control circuit boards because a high voltage is applied. • Refer to the circuit drawings separately provided to check the quality of the detailed parts (semiconductors) for mainten- ance. Trouble 1. The machine will not run even when stepping on the treadle while the power switch is ON. Check Point Check the power source voltage. (Try to plug into another outlet.) (1) Power indicator lamp (red LED) does Fuse blown: 3-phase 3A or 5A fuse (2 pcs.) not go ON. Single-phase 15A fuse (1 pc.) (Replace with new ones.) Parts to Be Replaced Ref. Page Fuse Control box (2) Power indicator lamp (red LED) is ON. 2. The machine stops during operation. (1) Power Indicator lamp (red LED) flickers. Check whether the connections are secured. (Check especially the 6P connector of the motor.) The machine pulley is too stiff to turn manually. [The machine or the motor (brake lining) is locked. Remove the cause and turn on the power. The machine should run normally.] Control box (2) Power indicator lamp (red LED) does not flicker. 3. The machine starts running just by turning on the power switch even with the treadle set in the neutral position. 4. The machine does not run at high speed. 5. The machine does not stop even if the treadle is returned to the neutral position. 6. Abnormal motor running (variation in rpm) 7. The brake produces abnormal noises during operation. 8. The operations related to the machine sole- noid do not work. (thread trimming, reverse rotation, thread wiper, and presser) 9. Abnormality related to automatic backtacking, etc. Power source voltage drop. (The motor is not out of order.) Check whether the high speed volume is set to "Low". (The range of the high speed control is from 215spm to the maximum.) If the machine stops after turning off the power switch, removing the synchronizer switch, then turning it on again, the synchronizer is out of order. (Use as a clutch motor for a while,.) Adjustment of brake clearance Check the 8-A fuse provided on the control circult board. Control box Control box Synchronizer Control box Motor Remove washer. 8-A fuse Control box Control box Operation panel P.35 P.16 P.36 - 33 -