Brother RH-9820 Service Manual page 222

8. ELECTRICAL MECHANISM
Problem #3 Feed base does not move at all when the start switch is depressed.
Cause
1. Malfunction of treadle unit
2. Malfunction of 2-pedal
switch
Malfunction of hand start switch
Work
Start
clamp
Problem #4 Feed base home position is shifted.
Cause
Incorrect home position adjustment
Sewing machine specifications and
memory switch settings do not
match.
Malfunction of encoder
213
Inspection/Remedy/Adjustment
With connector P6 (FOOT) inserted into the main
P.C. board, turn on the power and then measure
the voltages between pins 2-3 at the cord-side
connector. (No. 2 +, No. 3 −)
OK if the voltage is approximately 2 V at neutral
and approximately 4 V when the foot switch is
depressed as far as it will go.
5086Q
foot Disconnect connector P6 (FOOT) from the main
P.C. board, and check the continuity between
pins 5-6 and 7-8 at the cord-side connector.
OK if normally ∞ Ω, and 0 Ω when the foot switch
is depressed.
1201B
Inspection/Remedy/Adjustment
Switch to home position adjustment mode and
adjust the position of the feed base while
referring to "7-34. Adjusting the feed base X
home position and Y home position".
Check that the settings for memory switch No.
850 and No. 851 are correct while referring to
" 2-3. Memory switch setting method (Advanced)".
Check the mechanisms for the X axis, Y axis and
θ axis home position sensors while referring to
"2-6. Input checking method".
RH-9820
Replacement if a malfunction
Treadle unit
Foot switch
Foot switch cord assembly
Hand start switch
Replacement if a malfunction
Pulse motor X assembly
Pulse motor Y assembly
Pulse motor θ assembly