Brother S-710A Service Manual page 148

22. TROUBLESHOOTING
Problem
22. Sewing machine starts
operating before
presser foot is lowered
(solenoid-type presser
lifter specifications).
23. Presser foot does
not lower (solenoid-
type presser lifter
specifications).
24. Machine stops during
sewing.
25. Lower thread detector
does not operate.
26. None of the solenoids
operate.
141
• Is DIP switch 2 inside the control
box set to OFF?
Set DIP switch 2 to ON.
• Is the solenoid-type presser lifter
1P connector also connected?
If not using the 1P connector,
disconnect it.
• Treadle unit signal abnormality.
Adjust the depression stroke to the standard setting.
• Is the power supply voltage too low?
Check the power supply.
(If the power cord is too long or too many appliances are being run from
a single outlet, this may cause voltage drops which will in turn cause the
reset function to activate and stop the machine, even if the power supply
itself is normal.)
• Is the lower thread detector
connector inside the control box
disconnected?
Insert the connector securely.
• Is the lower thread detector relay
cord inside the machine head
disconnected?
Securely connect the cord.
• Is memory switch No. 16 set to ON?
Set memory switch No. 16 to OFF.
• Is the 8 A fuse inside the control
box blown?
If the 8 A fuse is blown, check
the resistances of
solenoids, and replace
solenoid that has an abnormal
resistance.
After this, replace the 8 A fuse.
Possible cause
all the
any
SL-710A
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