Panasonic SA-AK770PL, Service Manual

Page: 70 / 138

(Product reference value: 3,000±90Hz)
1. Connect a frequency indicator. (Fig 10)
2. Playback the middle portion of the test tape (QZZCWAT).
3. Adjust the motor screw so that the following output level is produced. (Fig 11)
Adjustment Range: 3,000 ± 90Hz (a constant speed)
Fig. 10
Fig. 11
13.1.5. Bias Voltage Check
1. Connect an electrical voltmeter. (Fig 12) (Fig 9 for location of Test point)
2. Set the function to “TAPE” position.
3. Insert a normal blank cassette tape (QZZCRA).
4. While pressing and holding down [REC ( )] button, press [TAPE ( )] button to pause the recording mode. (Repeat
pressing the buttons till the recording pause mode is activated.)
5. Check that the output level is within the standard range.
Standard Range: 20 ± 3mV
Fig. 12
13.1.6. Bias Frequency Check
1. Connect a digital frequency counter (Fig 13).
2. Set the function to “TAPE” position.
3. Insert a normal blank cassette tape (QZZCRA) and press “REC” mode on main unit.
4. Check that the output frequency is within the standard range.
Standard Value: 100 ±8 kHz
Fig. 13
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SA-AK770PL / SA-AK770GCP