Brother International TN-872B Instruction Manual - English and Spanish - Page 120

14. TROUBLESHOOTING GUIDE 14. FEHLERSUCHE 14. RECHERCHES DE PANNES 14. GUIA PARA LA LOCALIZACION DE FALLAS Problem 10. Trailing lengths of the upper threads are too short after thread trimming. Where to check ¡ Is the thread coming out of the cotton stand easily? If the thread is not coming out easily, check if the thread is caught on something. ¡ Is the tension of the pretension too strong? Adjust the pretension. ¡ Are the thread take-up spring tensions too strong? Make the thread take-up spring tensions weaker. ¡ Are the ranges of movement for the thread take-up springs too large? Reduce the ranges of movement of the thread take-up springs. ¡ Are the hooks of the movable knives damaged? Polish the hooks to remove the damage, or replace the damaged knife. ¡ Are the tension discs moving during thread trimming? If the tension discs are not moving, adjust the tension release mechanism. ¡ Is the timing correct during thread trimming? Adjust the timing for thread trimming. Page 44 52 65 66 78 81 85 · 86 Hook 11. Thread wiper is hitting the ¡ Is the thread wiper correctly positioned? needles. Adjust the thread wiper. 75 Needle up stop position is ¡ Is the needle up stop position too low? not consistently the same. Adjust the needle position sensor. 83 ¡ Is the V-belt tension too weak? Adjust the tension so that the V-belt shows a deflection of 10-20 mm 18 when pushed with a finger. 12. Broken needles ¡ Is the material being pushed or pulled with excessive force during sewing? If the needle tip is bent or broken, replace the needle. ¡ Does the needle pass the center of the needle hole in the feed dog? Check the needle down position. If the needle does not drop into the middle of the needle hole in the feed dog, re-install the feed dog. [842B, 847B, 872B] If the needle bar has been turned, turn it again to set it to the correct position. Caution ¡ 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. 91 (Step 3) - 105 - TN-840B, 870B (English) TL-840B (English)