Lower Thread Is Not Trimmed (Pulls When Material Is Removed); Feed Mechanism Does Not Operate Or Motor Is Out Of Step - Brother HE-800A Service Manual

5. TROUBLESHOOTING
Cause
Upper thread
scissors
Work clamp home
position sensor

5-25. Lower thread is not trimmed (pulls when material is removed)

Cause
Machine stopping
position
Fixed knife set

5-26. Feed mechanism does not operate or motor is out of step

Cause
Feed pulse motor
Upper thread
scissors
120
Check
Upper thread scissors
operation
Work clamp home
position sensor position
Check
Rotary hook touches
lower thread retainer at
the stop position
Fixed knife and movable
knife do not mesh.
Knife tip is bent
chipped.
Check
Cord connection
Upper thread scissors
position
Check if the cam opens
the stop plate.
Adjust the upper thread scissors to the standard
setting.
Adjust the work clamp home position sensor
position.
Adjust the needle up stop position.
Retainer
Adjust the fixed knife set installation position.
Fixed knife
or Repair or replace the knife.
Check the cord connections and contacts.
Remove and re-install the upper thread scissors.
Projection on scissors M is inserted.
* Always make sure that the upper
thread scissors are in the correct
position before use.
Adjust the cam position.
* If the feed mechanism operates when the cam has
not opened the stop plate, the cutter will bump
against the upper thread scissors.
Remedy
Remedy
Inner rotary
hook presser
Movable knife
Remedy
Page
89
82
Page
103
4021Q
96
4024Q
-
Page
-
91
4025Q
95
4018Q