12 Measurements And Adjustments - Panasonic SC-H M900 Service Manual

SC-HM900
J
Measurement Condition
Reverse-mode selector switch:
Tape edit: NORMAL
Record timer: OFF
Make sure head, capstan and press rolier are clean.
Judgeable room temperature 20 :t 5°C (68 :t 9°F)
Measuring instrument
EVM (Electronic Volmeter)
Digital quency counter E. HEAD R/PHEAD
Test tape
~
- Head azimuth adjustment (8 kHz, -20 dB); QZZCFM /. Fig.:3
- Tape speed gain adjustment (3 kHz, -10 dB); AZZCWAT .
- Playback gain adjustment (315 Hz, O dB); AZZCFM L I
- CrO2tape,QZZCRX
'
AzimuthScrew AzimuthScr8W
(Forward) (Reverso)
Ag. 4
12 Measurements and Adjustments
12.1 Cassette Deck Section
.
.
12.1.1 Head Azimuth Adjustment
(Deck 1/2)
CAUTION:
. Please replace both azimuth adjustment screw
(rhe5152zb) and springs (RM0331) simultaneosly when
readjusting the head azimuth. (shown in Fig. 2). Even if
you wish to readjust the head azimuth without replacing
the screws and springs, afine adjustment to the azimuth
screw and spring.
.
Please remove the screw-Iocking bond left on the head
base when replacing the azimuth screw.
If you wish to readjust the head azimuth, be sure to ad-
just with adhering the cassette tape closely to the mecha-
nism by pushing the center of cassette tape with your
finger. (shown in Fig. 3)
Play back 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-A) are maximized.
Perform the same adjustment in the reverse play mode.
After the adjustment, apply screwlock to the azimuth
adjusting screw.
A ~ CH
;
(PeOUT-A)
;~
,'u
o
:",u"""':::::::uu,
t@o
""" u... """ - -
EVM
--..
1.
2.
3.
Fig.1
T
(RHE5152ZB)
8 (RM80331)
Fig.2
i
I
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12.1.2 Tape Speed Adjustment
(Deck 1/2)
1.
2.
Set the tape edil button to "NORMAL" position.
Ingeríthe test tape (QZZCWAT)to DECK 2 and play-
back (FWD side) the middle portion of i1.
Adjust Motor VR (DECK2) for the outputvalue shown
below.
--..
3.
4.
, Adjustment target: 2940
-
3060 Hz (NORMAL
speed)
After alignment, assure that the output frequency of
the DECK 1 FWD is within :t 60 Hz of the value of the
output frequency of DECK 2 FWD.
UNIT
--..
(Rch)
liDI I
PBRj
.
(GND)
L
~
~-'-
~
~
-u-u..
O
-.. - c-
Digital frequency
counter
, ".
- 20..