6
6DRR-M31
6. Checking the back tension torque at the time
of recording and playback
Load a cassette type torque meter (Sony TW2111A at
the FWD side, Sony TW2121A at the REV side) and check
that the reading of the torque meter during playback is
9.8~58.5 mN-cm (1~6 g-cm) and that there is no
unevenness.
7. Checking the FF and REW torque
Load a cassette type torque meter (Sony TW2231) and
check that the value indicated by the torque meter for
winding and rewinding is between 686 mN-cm~
1.47 N-cm
(70~150 g-cm).
8. Checking the FF and REW time
Load a Type 1 tape (UD-1), and check that the time for
FF and REW is less than 120 seconds. When outside of
the specified range, check Steps 5 and 6.
9. Checking the erroneous erasure prevention,
and the metal and chrome switch operations
Check that detection lever is operating the switch properly
depending upon the presence or absence of a hole.
Adjusting and Checking the Electrical Section
Measuring instruments needed for the adjustments
(1) Low frequency oscillator
(2) Variable resistance attenuator
(3) Electronic voltmeter
(4) Oscilloscope
(5) Frequency counter
(6) Adjustment screwdriver
(7) Test tapes
MTT-111, MTT-114N, MTT-150, Type1 tape (UD-1)
(8) Mirror cassette for the transport (A-BEX TCC-902)
Adjustment precaution
(1) Before adjustments, use gauze or a swab moistened
with alcohol to wipe the surface of the heads, the
capstan shaft, and the pinch roller.
(2) Demagnetize the record/playback head and the
erase head with a head eraser.
(3) Completely demagnetize the driver to be used for
the adjustments.
(4) Unless otherwise specified, set the various operation
controls as indicated below.
Dolby NR switch: Off
1. Tape transport check
Load the mirror cassette for the transport, and illuminate
the area around the fixed guide of the record/playback
head with a lamp and observe.
Check that the tape edge is not hitting the tape guide
portion.
Note that the tape transport is the greatest factor affecting
the performance of the cassette deck. Never move the
inspection locations without good reason.
For information about replacement and adjustment of the
record/playback head, see the section “Adjustment and
checking of the mechanism”.
2. Tape speed check and adjustment
(1) Connect the frequency counter to the LINE OUT pin
and load the test tape (MTT-111).
(2) Playback FWD side of the test tape. At about halfway
through the tape, where the tape transport is stable,
confirm that the frequency counter will have a
reading within the range of 3,000 Hz ±10 Hz.
(3) Check REV side also that the counter reading
indicates within 2955~3045Hz.
Note: Adjust within 30 seconds, after pre-heating
(Play) of 20min, or more.
LINE OUT
PB Amp
MTT-111
3000
3000Hz
10Hz
Frequency counte
