Cassette Deck Section - Panasonic SC-AK48 Service Manual

SA-AK48

13.2. Cassette Deck Section

13.2.1. Measuring Instruments and
Special Tools
• Digital frequency counter
• EVM-AC (AC Electronic voltmeter)
• Test tape
QZZCFM : Head azimuth adjustment
QZZCWAT : Tape speed adjustment
QZZCRA : Normal reference blank tape
QZZCRX : CrO2 tape
13.2.2. Head Azimuth Adjustment
(Deck 1/2)
Caution:
• Please
replace
(RHE5152ZB) and springs (RMB0331) simultaneously
when readjusting the head azimuth. (Shown in Fig.5).
Even if you wish to readjust the head azimuth without
replacing the screws and springs, a fine adjustment
cannot be done because of the screw-locking bond
adhered 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.6)
1. Connect the measuring instrument as shown in Fig.7.
2. Playback the azimuth adjustment portion (8kHz, -20dB) of
test tape (QZZCFM). Adjust the azimuth adjusting screw
until the outputs of the L/R-ch are maximized. (Refer to
Fig.8)
Make sure that the difference in the peak level between the
left and right channels does not exceed 0.5dB.
3. Perform the same adjustment in reverse playback mode.
Checking of the level difference forward and reverse
directions
4. Playback the playback gain adjustment portion (315Hz,
0dB) of test tape (QZZCFM). Check if level difference
between forward and reverse direction is within 1.5dB.
5. After the adjustment, apply screwlock to the azimuth
adjusting screw.
both azimuth adjustment screws
Fig.5
13.2.3. Tape Speed Adjustment (Deck 1/2)
1. Insert the test tape (QZZCWAT) to Deck 2 and playback
(FWD side) the middle portion of it.
2. Adjust motor VR (Deck 2) for the output value shown below.
Adjustment target : 2940 - 3060Hz (NORMAL speed)
3. After alignment, assure that the output frequency of the
DECK2 REV and DECK1 FWD are within ±45Hz and
±60Hz respectively of the value of the output frequency of
DECK2 FWD.
36
Fig.6
Fig.7
Fig.8
Fig.9
Fig.10