Electrical Adjustments - Sony HCD-GT111 Service Manual

DECK SECTION 0 dB = 0.775V
1. Demagnetize the record/playback head with a head demagne-
tizer.
2. Do not use a magnetized screwdriver for the adjustments.
TEST TAPE
Tape Signal
P-4-A063 6.3 kHz, -10 dB
RECORD/PLAYBACK HEAD AZIMUTH ADJUSTMENT
Procedure:
1. Mode: Playback
test tape
MIC board
P-4-A063
PHONES jack
(6.3 kHz, −10 dB)
(J702)
set
2. Turn the adjustment screw and check output peaks. If the peaks
do not match for L-CH and R-CH, turn the adjustment screw
so that outputs match within 1dB of peak.
within
L-CH
1 dB
peak
Output
level
R-CH
peak
Screw
position
L-CH
peak
3. Mode: Playback
test tape
MIC board
P-4-A063
PHONES jack
(6.3 kHz, −10 dB)
(J702)
set
waveform of oscilloscope
in phase 45° 90° 135° 180°
good
4. After the adjustments, apply suitable locking compound to the
pats adjusted.
SECTION 6

ELECTRICAL ADJUSTMENTS

Used for
Azimuth Adjustment
level meter
+
–
within
1 dB
Screw
position
R-CH
peak
oscilloscope
V H
wrong
HCD-GT111/GT222/GT444/GT555
Adjustment Location: Record/Playback/Erase Head
CD SECTION
Note:
1. CD Block is basically designed to operate without adjustment. There-
fore, check each item in order given.
2. Use YEDS-18 (PART No. 3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10MΩ impedance.
4. Clean the object lens by an applicator with neutral detergent when the
signal level is low than specifi ed value with the following checks.
TEST DISC LIST
Use the following test disc on electrical checks.
YEDS-18 (PART No. 3-702-101-01) or
PATD-012 (PART No. 4-225-203-01)
S-CURVE CHECK
oscilloscope
(DC range)
CD board
TP106 (FE)
+
TP124 (VC)
–
Procedure :
1. Connect an oscilloscope to TP106 (FE) and TP124 (VC).
2. Turn the power ON.
3. Load a disc (YEDS-18) and actuate the focus search. (In con-
sequence of open and close the disc tray, actuate the focus
search)
4. Confi rm that the oscilloscope waveform (S-curve) is symmet-
rical between A and B. And confi rm peak to peak level within
1.8 ± 0.5 Vp-p.
S-curve waveform
Note:
•
Try to measure several times to make sure than the ratio of A : B or B
: A is more than 10 : 7.
•
Take sweep time as long as possible and light up the brightness to
obtain best waveform.
symmetry
A
within 1.8 ± 0.5 Vp-p
B
21