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13. Trap Coil
and Bias
Leakage
Adjustment
Test Setup:
A)
Trap coil adjustment
checking point
record
playback
aaa
amp
amp
circuit
bias osc
circuit
board
circuit board
board
B)
Bias leakage adjustment
VTVM
REC Amp
LINE
OUT
jack
Specification:
Less than -10 dB
(Trap Coil Adjustment)
Less than -35 dB
(Bias Leakage Adjustment)
Notes:
(1)
Use a non-metallic screwdriver.
(2)
Do
not
use
shielded
wire as the lead of
the VI'VM.
Trap Coil Adjustment
Set the record volume control (MIC and AUX)
counterclockwise to the full.
Place the unit in the stereo-record mode.
Adjust L507 and L508 so that the VIT'VM con-
nected between
the checking point and ground
reads a minimum (less than -10 dB).
Bias Leakage Adjustmént
Set the record volume control (MIC and AUX)
clockwise to the full.
Place the unit in the stereo-record mode.
Set the MONITOR
switch to TAPE.
Adjust L301 and L401 so that the VTVM reads
a minimum (less than -35 dB).
Change the MONITOR
switch to SOURCE
and
make sure that the VTVM reads less than -35 dB.
L301 (L-CH forward run)
L401 (R-CH forward run)
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