Brother International TN-872B Instruction Manual - English and Spanish - Page 119

14. TROUBLESHOOTING GUIDE 14. FEHLERSUCHE 14. RECHERCHES DE PANNES 14. GUIA PARA LA LOCALIZACION DE FALLAS Problem 6. Large degree of puckering (excess tension) Where to check ¡ Is the upper thread tension too strong? Make the upper thread tension as weak as possible. ¡ Is the lower thread tension too strong? Make the lower thread tension as weak as possible. ¡ Are the thread take-up spring tensions too strong? Make the thread take-up spring tension as weak as possible. ¡ Are the ranges of movement for the thread take-up springs too large? Make the ranges of movement of the thread take-up springs as small as possible. ¡ Is the presser foot pressure too weak? Increase the presser foot pressure. ¡ Is the sewing speed too fast? Reduce the sewing speed slightly. Page 51 51 65 66 52 Motor instruc- tion manual 7. Upper thread trimming errors ¡ Is the timing correct during thread trimming? Adjust the timing for thread trimming. ¡ Are the tips of the movable knives damaged or bent? Replace the movable knife which is damaged. ¡ Is there too much clearance between the tips of the movable knives and the rotary hook stoppers? Adjust so that the clearance is 0.05-0.2 mm. ¡ Is the tension release mechanism working correctly? Adjust the tension release mechanism. ¡ Are the tips of the movable knives in the correct positions? Adjust the positions of the movable knives. 85 · 86 78 79 81 79 8. Lower thread trimming ¡ Are the tips of the movable knives too low? errors Are the tips of the movable knives damaged or bent? 78 Replace the movable knife which is damaged. ¡ Are the rotary hooks too high? Push the rotary hooks down to install them correctly. 68 9. Lower thread is tangled at the sewing start. Lower thread Spinning of bobbin during thread trimming 80% ¡ Is the bobbin spinning direction correct when the lower thread is being pulled? Set the bobbin so that it turns in the opposite direction to the rotary hook. ¡ Is there too much thread wound onto the bobbin? The bobbin winding amount should not be more than 80%. ¡ Is the free spinning prevention spring attached? Attach the free spinning prevention spring. ¡ Is the bobbin turning smoothly? If the bobbin is not turning smoothly, replace the bobbin. ¡ Is a bobbin other than the light-alloy bobbins specified by Brother being used? Use only bobbins which are specified by Brother. 41 · 42 38 40 40 - 104 - TN-840B, 870B (English) TL-840B (English)