Sharp QT-15XW Service Manual page 3

g s = OQT-15XW
MECHANICAL ADJUSTMENT
TORQUE CHECK AT PLAY, FAST FORWARD AND
REWIND MODES (See Table 3.)
Put a torque meter cassette in the cassette holder of the unit,
and see that the measured torque in each mode is normal as
shown in Table 3.
PINCH ROLLER PRESSURE CHECK
1. Place the unit in playback mode.
2. Push the pinch roller, at the point @ shown in Figure 3—1,
by using a tension gauge (500 g) so that it will come off the
capstan. Then, slowly release the tension until the pinch
roller hits the capstan again (i.e., the pinch roller is about to
rotate again). Check, then, the tension gauge is reading
300 g to 400 g.
3. If the reading is outside the range of 300 g to 400 g, replace
the pressure spring of the pinch roller. |
RECORD/PLAYBACK HEAD AZIMUTH ADJUSTMENT
1. Connect instruments as shown in Figure 3—2.
2. Adjust the head azimuth adjusting screw so that the output
signal will have maximum waveform.
TAPE SPEED ADJUSTMENT
1. Connect instruments as shown in Figure 3—3.
2. Put a screwdriver (for high-frequency use) into the hole of
the motor, and adjust the variable resistor so that the
output frequency is 2955 Hz to 2980 Hz on frequency
counter.
Test Tape
MTT-111L
(3 kHz)
Measured torque
80 ~ 130 g-cm
| Rewind | TW-2231_— | 80~ 130 gem __
Tension Gauge
(500 g)
A)
Pinch Roller Pressure
Spring
Figure 3—1
Pinch Roller
ELECTRONIC
Playback VOLTMETER
Mode
Earphone Jack
(J101)
Test Tape
MTT-113
(6.3 kHz)
Record/Playback
Head :
Fe Figure 3—2
Record/Playback Earphone Jack
Head (J101)
Playback Mode /
oes
Screwdriver
for high-freq.
FREQUENCY
COUNTER
Figure 3—3
ELECTRICAL ADJUSTMENT
PLAYBACK AMPLIFIER SENSITIVITY CHECK
1. Connect instruments as shown in Figure 3—4.
2. Set the mode selector switch at tape, the volume control
knob at max.
3. Playback a test tape (TEAC, MTT-118, 1 kHz, 250 pWb/
mm,—10 dB prerecorded).
4. See that the electronic voltmeter is reading about 130mV.
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ELECTRONIC OSCILLOSCOPE
Earphone Jack (J101) VOLTMETER
Playback Mode
Record/Playback
Head
6 ohm
Figure 3—4