Brother International MD-817 Service Manual - Page 54

Control, Troubleshooting, Guide, Outline

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CONTROL BOX TROUBLESHOOTING GUIDE OUTLINE PROBLEM 1. Motor won't operate. Lamp does not illuminate when power is ON. (Fuse has blown.) 2. Motor won't operate. Lamp illuminates when power is ON. 3. Machine abnormal high-speed rotation when power is ON. 4. When power is ON: Thread trimmer continues. Reverse continues. Brake remains ON. All continue. 5. With treadle forward, excessive high speed; will not stop. 6. With treadle depressed to maximum, high-speed rotation changes. (High-speed rotational irregularity) 7. During speed reduction from high speed, brake doesn't function, or great deviation of needle (lower) stopping position. CHECK METHOD (1) Fuse is replaced and fails again. (2) Operation possible after fuse replacement. (1) LED flashes during forward backtack. (2) Motor roars or hums. (3) Others REPLACEMENT PART D printed-circuit board PTR, D (If PTR is broken then motor frame assembly.) Due to operation of overvoltage protection circuit; no abnormal condition. Treadle printed-circuit board tantalum C1, HIC5 CPU, brake TR 1 HIC1, HIC2, HIC6 HIC4, HIC5, HIC6 D printed-circuit board PTR (singlephase 110V) Thread trimmer TR2 Reverse TR5 Brake TR1 CPU HIC2 HIC6 Poor soldering of treadle printed-circuit board. HIC6 HIC3 - 50 -

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CONTROL
BOX
TROUBLESHOOTING
GUIDE
OUTLINE
PROBLEM
CHECK
METHOD
REPLACEMENT
PART
1.
Motor
won't
operate.
Lamp
does
not
illuminate
when
power
is
ON.
(Fuse
has
blown.)
(1)
Fuse
is
replaced
and
fails
again.
D
printed
-circuit
board
PTR,
D
(If
PTR
is
broken
then
motor
frame
assembly.)
(2)
Operation
possible
after
fuse
re-
placement.
Due
to
operation
of
overvoltage
protec-
tion
circuit;
no
abnormal
condition.
2.
Motor
won't
operate.
Lamp
illuminates
when
power
is
ON.
(1)
LED
flashes
during
forward
back-
tack.
Treadle
printed
-circuit
board
tantalum
C1,
HIC5
(2)
Motor
roars
or
hums.
CPU,
brake
TR
1
(3)
Others
HIC1,
HIC2,
HIC6
3.
Machine
abnormal
high-speed
rotation
when
power
is
ON.
HIC4, HIC5,
HIC6
D
printed
-circuit
board
PTR
(single-
phase
110V)
4.
When
power
is
ON:
Thread
trimmer
continues.
Reverse
continues.
Brake
remains
ON.
All
continue.
Thread
trimmer
TR2
Reverse
TR5
Brake
TR1
CPU
HIC2
5.
With
treadle
forward,
excessive
high
speed;
will
not
stop.
HIC6
6.
With
treadle
depressed
to
maxi-
mum,
high-speed
rotation
changes.
(High-speed
rotational
irregu-
larity)
Poor
soldering
of
treadle
printed
-circuit
board.
HIC6
7.
During
speed
reduction
from
high
speed,
brake
doesn't
func-
tion,
or
great
deviation
of
needle
(lower)
stopping
position.
HIC3
-
50
-