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6-2-6 REVERSE HOLDING CIRCUIT
(Refer to Fig. 6-41)
ICB MCl4011BCP
Rl41 22K OV
OV
2
Rl39
Rl33
Rl34
3
IOOK 0.6V
47K
IOK
I ICS
5
IC 8
6
Rl'36
47K
:!
~
:!
.,
o"'
a,
!!!
.,,
"'
0::
u"'
ii:
"'
9
Rl37
IOI<
8
ov
10.5V
Rl35 IM
C39
2.2/2!S(Ml
,ca
TR46
TR4!5,46
2SC94!SL(P,Ql
TR49,50
2S0!571(K,Ll
Suppose the REV key is pressed when the
machine is in FWD mode. ICI
@
becomes
"H", and "H" is supplied to the emitter of
TR96. Because the base of TR96 is always
"L", the "H" of the emitter of TR96 will go to
the collector of TR96. IC8
Q)
and
@
be-
come "H", IC8
8)
"L", and the "H" of TR96
collector is supplied to IC8
®
through Rl 36
and Rl37, and therefore, "H" to IC8
@.
This "H" is supplied to the base of TR46
through RI42 to make the collector of TR46
"L". Consequently the base of TR49 is "L"
and the collector of TR49 "H". Since IC8
@)
is "H" in FWD mode, C39 is charged. There-
fore, IC8
(D
is kept at "H" until C39 is dis-
,.
,-.
. .
..,
:!
0::
SR2-I
Fig. 6-41
charged even if IC8
@)
becomes "L". Because
IC8
(D
and
G)
become "H", IC8
G)
"L".
The base of TR45 becomes "L" through RI 39
and the collector "H", and TRS0 is energized.
"L" of the collector of TRS0 turns TR47 ON
through R147 and RISO. Therefore, current
runs to RL6 and TRS0 through TR47, and RL6
is working. The RL6 relay worked remains
in
that position even when the power is turned
OFF, and when the reverse voltage is applied,
it is reset. When the TR6 is worked, the output
from ICl
@
is taken into ICI
@
through
the switch of RL6 and the direction is decided
for REV mode by the microcomputer.
- - - - - - - - - - - - - - - - SERVICE
MANUAL
GX-747dbx - - - - - - - - - - - - - - - -
25
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