Brother S-7300A Service Manual page 190

11. TROUBLESHOOTING
Problem
22 Incorrect thread trimming
(Upper thread is not being
trimmed.)
(Lower thread is not being
trimmed.)
0.1 - 0.3mm
23 Broken needle
24 Oil gauge (1) is not visible
in oil gauge window.
25 The presser foot does not
lift using the knee lifter.
26 Thread take-up
stopper and
take-up spring are twisted
together.
179
・ Is the needle properly installed?
If it is incorrect, install the needle correctly.
・ Is the blade of the knife damaged or worn?
Replace the knife.
Knife = Other than premier specifications : fixed knife, movable
knife
Premier specifications : upper knife, lower knife
・ Tilt the upper knife forward slightly. (About 0.1 to 0.3 mm) (Premier
specifications)
Is there not enough of a meshing amount between the knives?
・ Adjust so that the tips of the movable knife and fixed knife are
meshing. (Other than premier specifications)
・ Adjust the tip of the upper knife to the lower knife index position so
that the knives mesh.(Premier specifications)
0949D
・ Is the material being pushed or pulled with excessive force during
sewing?
・ Is the needle properly installed?
If it is incorrect, install the needle correctly.
・ Is the needle tip bent? Is the needle tip broken, or is the needle hole
blocked?
Replace the needle.
・ Is the needle and rotary hook timing correct?
Adjust the height of the needle bar.
Adjust the clearance between the needle and the tip of the
rotary hook.
・ Is the needle and feed mechanism timing correct?
Adjust to the standard timing.
・ Try pressing the special locus key and selecting No. 2 or No. 3.
0469M
NOTE:
・ It is extremely dangerous to leave any pieces of broken
needle sticking in the material.
If the needle breaks, search for all pieces until the whole of
the needle is found again.
・ Furthermore, we recommend that thorough steps be taken
to account for such needles to comply with product liability
regulations.
Is the oil tank empty?
・
Fill the oil tank with oil.
0923D
Is the knee lifter being used at the needle up position while thread
・
trimming is disabled?
Enable thread trimming.
Is the knee lifter being used before the sewing machine has stopped?
・
Adjust the tension release switching plate upward to retard the
tension release timing.
spring
Adjust the tension release switching plate upward to retard the
・
thread
tension release timing.
Possible cause
S-7300A
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