Tascam 122 Service Manual page 13

122
are shorted. Therefore,
not flow to 0509 and
even if transistor 0602
reproduce mode signal
from U601.
base current does
it will remain off
turns on with a
(H level) supplied
e. When C526 is fully charged (in approxi ­
mately 1.5 seconds) after power is switched
on, the base current of 0521 stops and it
turns off. (C526 and R547 provide the
delay time of about 1.5 seconds.)
f . As 0521 is off, 0508 turns off, having its
base current cut off. Now 0509 is ready
for operation. This process keeps the pinch
roller solenoid inactive for approximately
1.5 seconds after power is switched on.
REPRODUCE DELAY CIRCUIT
I
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U601
R619
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p~~
0;'=-2
_..,...~R6"'''--''-1f{
L_
FROM
+23V REGULATED
POWER SUPPLY 10517)
0606
POWER DELAY CIRCUIT
RSl2
R618
,-------------,
I I
I R559 I
I
I C526 R547
~1--
.........
w.-~-1i-{
:
0513
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L _ _ _ _ _ _ _ _ _ _ _ _
-..l
I
2) Reproduce delay circuit
The circu~try is designed so that, in the repro ­
duce mode, the pinch roller solenoid operates
after the head base solenoid has completed
operation. The reproduce delay circuit
delays pinch roller operation until the com­
pletion of the head base solenoid operation.
Fig. 3-7 and 3-8 are a flowchart and timing
diagram, respectively, of the process which
begins with the output of a reproduce mode
signal (H level) from pin 12 of the system
control IC and ends with the energizing of the
pinch roller solenoid. In Fig. 3-7, operations
of the reproduce delay circuit are enclosed in
bold boxes.
r---- - PINCH ROLLER SOLENOID DRIVE CIRCUIT - - --,
DRIVER
DRIVER
,--------,
I . 1
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0514
.:
L ________ .1
0694
J
L692
HEAD BASE
SOLENOID
1 - - - - - - - ,
:
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I
0:509
0695
Fig. 3-6 Pinch roller solenoid drive circuit
FLASHING CIRCUIT
~---------------I
I I
I I
: I
I I
C508 R521
I
I
I
0505
I
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I
L _ _ _ _ _ _ _ _ _ _ _ _ ___ _
J
FLASHING CIRCUIT
r----------------,
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I
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I
0509
I
I I
L _________ _ _ _ ___
.l
I NO LOAD I
+13\1
+39\1
R537
0507
13