Brother RH-9820 Service Manual page 123

Measurement position
7) Provisionally screw in the two remaining socket
bolts with washers (g) at the back of the
machine head until they are almost fully
tightened, and then place the motor on the
lower shaft side.
8) Insert a screwdriver into the gap between the
motor holder (d) and the bed (k) and move the
upper shaft motor unit (c) to the left to adjust
the tension of the belt (h) to within the range
given below.
• When using a new belt: 130 - 140 N
• When reusing an old belt: 90 - 100 N
* Be sure to use a belt tension gauge to measure
the belt tension, and measure at the position
shown in the illustration.
* The belt tension gauge should be set to
measure a unit weight of 0.04 kg/m, a belt width
of 15 mm and a span length of 92 mm.
9) Tighten the two socket bolts with washer (g).
10) Tilt back the machine head and fully tighten the
socket bolt with washer (f) at the front.
11) Check that the D cut section (D) of the encoder
is facing directly to the right ± 10° at this
time.
* If it is not in this position, repeat steps 3 to
10. (If it is not in the correct position, the
adjustment in "7-35. Adjusting the needle up
signal home position for the upper shaft and
upper shaft motor" will not be possible.)
NOTE:
If you do not have a belt tension gauge, adjust
so that
approximately 1 mm when a pressure of 5 N is
applied to the middle of the span (the
measurement position shown in the illustration).
RH-9820
the amount of deflection
6. ASSEMBLY
is
0856B
114