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5. ELECTRICAL
ADJUSTMENTS
Precautions for Adjustment and Measurement
1.
"IO
Before
playing
back the test tape, thoroughly demag-
netize the heads, capstan and similar metal parts using
an erase, as the test tape-recorded tone is easily erased.
. Do not place the test tape on any measuring instrument.
. Do not put the test tape near a place where the eraser is
used.
. Method
of Demagnetization:
Turn
the eraser
power
switch on at a position far away from the heads. Bring
the eraser close to the heads, capstan and other parts to
be demagnetized, and move it up and down four er five
times to demagnetize.
Slowly separate the eraser far
away from the parts, and turn the power switch off.
. Do not use any magnetized adjusting tool. if necessary,
demagnetize with a bulk eraser from time to time in the
course of each adjustment.
. Do not turn semi-fixed resistor or coil more than needed.
. Measure
speed
and
wow
and
flutter
in the
normal
Operating state.
. Do not apply locking bond excessively.
. Check the line voltage and the output of low frequency
oscillator
2 —
3 times a day to see if they are set as
specified.
5.1
Head Azimuth Adjustment
. Play the test tape MTT256 back. Adjust the head azimuth
adjusting screw for maximum VTVM reading.
. If the peak levels of the left and right channels are
different set the screws to obtain the mechanical center
between the peaks.
. After adjustment, repeat the playback and stop settings
several times to confirm no azimuth deviation.
. After adjustment, lock the screws with bond.
Mode: Playback
Test Tape
1.
2. Adjust the adjustirig resistor (RMO5) on the PMO1 P.W.
Play the 3kHz signal of the test tape MTT-111 back.
Mode: Playback
Test Tape
Frequency
MTT-111
Counter
5.3.
Playback Equalizer Measurement
1. Adjust the tape selector switch to NORMAL.
. Play the 315Hz signal of the test tape MTT-256 back.
The VTVM at OdB.
. Play the 12.5kHz signal of the test tape back. Confirm a
frequency response of 0 to 1dB in reference to the 315Hz
signal level.
Then, play the 12.5kHz signal back. Set the tape selector
to CrO2, Metal. Confirm the 12.5kHz signal readings at
— 4.5dB, +1dB.
Mode:
Playback
_ Test Tape
VTVM
MTT-256
14 kHz
O
X
©
Line Output
5.4
Playback Level Adjustment
the NR switch OFF.
. Play the test tape MTT-150 back. Adjust RKO3(L) and
RKO4(R) so that the voltage of JKO7 © pin and JKOO®@
pin is 100 mV. In this operation, make sure the voltage
of LINE OUT reads 500 mV + 1 dB.
NOTE:
1. Proceed both for the right and left channels in the same
way.
Mode:
Palyback
Test Tape
VTVM
MTT-150
O
O
JKO7 #5 pin
JKO9 #2 pin
5.5
Level Meter Adjustment
1. Adjust the Tape Selector Switch to NORMAL and turn
the NR switch OFF.
2. Play the test tape MTT-150 back. Adjust RK73(L) and
RK74(R) at +3dB Level Meter reading.
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