Panasonic SA-VK81DGCP, Service Manual

Page: 67 / 154

19.1. Cassette Deck Section
· Measurement Condition
− − − −
Reverse-mode selector switch:
− − − −
Tape edit: NORMAL
− − − −
Make sure head, capstan and press roller are clean.
− − − −
Judgeable room temperature 20 ± 5 °C (68 ± 9°F)
· Measuring instrument
− − − −
EVM (DC Electronic volmeter)
− − − −
Digital frequency counter
· Test Tape
− − − −
Tape speed gain adjustment (3 kHz, -10 dB);
QZZCWAT
19.1.1. Head Azimuth Adjustment (Deck
1/2)
Caution:
·
Please replace both azimuth adjustment screw and springs
simultaneously when readjusting the head azimuth. (shown
in Fig. 2) Even if you wish to readjust the head azimuth
without replacing the acrews and springs, a fine adjustment
to the azimuth screw and spring.
·
Please remove the screw-locking bond left on the head
base when replacing the azimuth screw.
·
If you wish to readjust the head azimuth, be sure to adjust
with adhering the cassette tape closely to the mechanism
by pushing the center of cassette tape with your finger.
(shown in Fig. 3)
1. Playback the azimuth adjustment portion (8 kHz, -20dB) of
the test tape (QZZCFM) in the forward play mode. Vary the
azimuth adjustment screw until the output of the R-CH (PB
OUT-R) are maximized.
2. Perform the same adjustment in the reverse play mode.
3. After the adjustment, apply screwlock to the azimuth
adjusting screw.
19.1.2. Tape Speed Adjustment (Deck 1/2)
1. Set the tape edit button to “NORMAL” position.
2. Insert the test tape (QZZCWAT) to DECK 2 and playback
(FWD side) the middle portion of it.
3. Adjust Motor VR (DECK 2) for the output value shown
below.
Adjustment target: 2940 ~ 3060 Hz (NORMAL speed)
4. After alignment, assure that the output frequency of the
DECK 1 FWD are within ±60 Hz of the value of the output
frequency of DECK 2 FWD.
Fig. 1
19.1.3. Bias and Erase Voltage Check
1. Set the unit “AUX” position.
2. Insert the Normal blank tape (QZZCRA) into DECK 2 and
the unit to “REC” mode (use “
l
REC/STOP” key).
3. Measure and make sure that the output is within the
standard value.
Bias voltage for Deck 2 14±4mV (Normal)
Erase voltage for Deck 2 80mV (Normal)
Fig. 2
Fig. 3
19 Measurements and Adjustments
67
SA-VK81DGCS / SA-VK81DGCP
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