Troubleshooting Guide - Brother SU-877A Instruction Manual

15. TROUBLESHOOTING GUIDE

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Be sure to check the following before calling an authorized service station.
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If the suggestions given below do not solve the problem, turn off the power and contact the place of purchase or
your nearest Brother dealer.
Turn off the power switch and disconnect the power cord before carrying out troubleshooting, otherwise the
machine will operate if the treadle is depressed by mistake, which could result in injury.
* When using a clutch motor, the motor will keep turning even after the power is switched off as a result of
the motor's inertia. Wait until the motor stops fully before starting work.
Problem
1. Sewing machine pulley
doesn't turn.
2. Poor thread tightening
3. Upper and lower threads
are breaking.
CAUTION
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Is a breaker or fuse blown?
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Is the power cord disconnected?
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Is the V-belt installed?
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Is the machine properly threaded?
If it is incorrect, thread the thread correctly.
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Is the thread take-up spring operating range too small?
Adjust the operating range of the thread take-up spring.
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Is the upper thread tension and/or lower thread tension too low?
Adjust the upper and lower thread tensions.
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Is the bobbin scratched?
If the bobbin is damaged, smooth it with an oiled grindstone or re-
place it.
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Is the needle tip bent? Is the needle tip blunt?
If the needle tip is bent or broken, replace the needle.
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Is the needle properly installed?
If it is incorrect, install the needle correctly.
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Is the machine properly threaded?
If it is incorrect, thread the thread correctly.
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Is the rotary hook properly lubricated?
If the oil level is below the "L" (low) level mark on the oil pan, add
more oil.
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Is dust or thread in the rotary hook?
Clean the rotary hook.
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Is the upper thread tension too strong or too weak?
Adjust the upper thread tension.
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Is the rotary hook, feed dog or other part damaged?
If they are damaged, smooth them with an oiled grindstone or re-
place the damaged parts.
SU-877A/B, TU-878A/B (English)
15. TROUBLESHOOTING GUIDE
15. FEHLERSUCHE
15. RECHERCHES DE PANNES
15. GUIA PARA LA LOCALIZACION DE FALLAS
Where to check Page
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29 - 33
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