Sony LBT-A57CD Service Manual page 56

© Standard Record:
Deliver the standard input signal level to the input
jack and set the REC LEVEL control to obtain the
standard output signal level.
— Record Mode—
AF_OSC
Cyl
| ame
ILooo |
a Leees
vTVM
6002
LINE IN LINE OUT
'CN504 'CN504
pin@: | pin@:Leh
pin@:Reh, pin@:Reh,
Standard Input Level
input terminal LINE IN
source impedance 10k
input level 0.25V (=10dB)
Standard Output Level
output terminal LINE OUT,
load impedance 47k
output level 0.44V (=3dB)
Test tape
Type Signal Used for
P-4-A100 10kHz, —10dB Azimuth Adjustment
P-4-L300 315Hz, 0dB PB Level Adjustment
WS-48B 3k11z, 0dB. Tape Speed Adjustment
Record/Playback Head Azimuth Adjustment
DECK A] [DECK B
Procedure:
1. Mode: FWD playback
test tape
P4100
(lOkH2, ~ 1008) VTVM
OT
© OUT
'CN504
pin@:Leh
pin@:Reh
2. Turn the adjustment screw for the maximum output
levels. If these levels do not match, turn the adjust-
ment screw until both of output levels match together
within 1dB
LCH
Si 'output
oi level within
103
RCH
peak
Serew
=
angle
sition
LCH peak RCH peak
3. Phase Check
Mode: playback
test tape
4.4100
10kHz, -10dB) oscilloscope
§ LCH ATKD
LINE OUT
[ons
pin@:Lch
pin@):Rch.
Screen pattern
O@OO®
in phase 45° 90° 15° 180°
good wrong
4. Set in the REV mode and repeat the step 1-3.
5. After the adjustment, lock the screws with locking
compound.
Adjustment Location: Record/playback head
FWD REV
%
Adjustment screw
Tape Speed Adjustment [DECK A] [DECK B]
Procedure :
Mode: playback
test tape
WS-48B
(kHz, 0dB) frequency counter
ATKQ
og
'CN504
pin@:Leh
pin®:Rch,
ee
Perform high speed adjustment before normal speed
adjustment.
(High speed adjustment)
1. Continue pressing the SYNCHRO DUBBING HIGH
SPEED switch.
2. Check that frequency counter reading is within the standard
value 6,000+ 60Hz.
3. If out of the standard, adjust each RV72 so that the
frequency counter reading satisfies 6,000+ 60Hz on both A
and B decks.
4. Change over to Rev playback status, and repeat the
above steps 1 to 3.
(Normal speed adjustment)
1. Continue pressing the SYNCHRO DUBBING NORM
SPEED switch.
2. Check that the frequency counter reading is within the
standard value 3,000 + 30Hz.
3. If out of the standard, adjust each RV71 so that the
frequency counter reading satisfies 3,000 30Hz on both A
and B decks.
4. Change over to REV playback status, and repeat the above
steps 1 to 3.
Frequency difference between the beginning and the end of the
tape should be within 3%.
Frequency difference between deck A and deck B the begin-
ning of the tape should be within 1.0%.
Adjustment Location :
MD-A, MD-B board
Playback Level Adjustment
DECK A] [DECK B
Procedure :
Mode: playback
test tape
P4300 yTvM
(315kH12, 0dB)
4TkQ oY}
'CNS04
[ome ie
pin@):Rch,
Adjust RV11 (L-CH), RV21 (R-CH) so that the reading on
VTVM meets the adjustment limits below.
Adjustment Limits :
LINE OUT level: —7.7+0.5dB (0.30 —0.33V)
Level difference between channels: less than 0.5dB
Check that the LINE OUT level does not change in
playback mode while changing the mode from playback
to stop several times.
Adjustment Location: MD-A, MD-B board
Record Bias Adjustment |DECK B
Setting :
REC LEVEL control : Standard Record (See page 7).
Procedure :
1. Mode : record
AF OSC i dt
inrecord tape
uae 5-123
oto
Tl 000 set
one tiene
600
LNé IN
ese 315He, 63mV_ (—21.84B)
amy
L pin@:Reh.