Sony SLV-7700KME, Service Manual

Page: 98 / 135

7-4
2-4-2. RF Level Check (BD-21 Board)
Signal Reference disc
Measurement + : TP RF
point – : TP VC
Measuring
Oscilloscope
instrument
Specified Confirm that oscilloscope waveform is clear
value and check RF signal level is correct or not.
[Check Method]
1)
Connect oscilloscope to test point TP (RF) on BD-21 board.
2) Turned Power switch on.
3) Put disc (YEDS-18) in to play the number five track.
4) Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.
2-4-3. E-F Balance (Traverse) Check (BD-21 Board)
Signal Reference disc
Measurement + : TP TE
point – : TP VC
Measuring
Oscilloscope
instrument
Specified A
×
100=less than ± 20%
value B
[Check Method]
1)
Connect oscilloscope to test point (TE) on BD-21 board.
2) Turned Power switch on.
3) Connect the SOL301 and SOL302 on the CD-169 board with
solder.
4) Put disc (YEDS-18) in to play the number five track.
5) Press the PLAY button in playback.
6) Press the RETURN button. (The tracking servo and the
sledding servo are turned OFF.)
7) Check the level B of the oscilloscope’s waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B
×
100=less than ± 22%
Fig. 7-2-7.
Note :
A clear RF signal waveform means that the shape “
≈
” can
be clearly distinguished at the center of the waveform.
8) Press the RETURN button. (The tracking servo and sledding
servo are turned ON.) Confirm the C (DC voltage) is almost
equal to the A (DC voltage) is step 6.
9) Remove the soldering installed in step 3.
Fig. 7-2-8.
Fig. 7-2-9.
Center of the waveform
B
A (DC voltage)
level : 13.
±
0.6 Vp-p
0V
Traverse waveform
level : 1.3 Vp-p
+0.25
–0.20
VOLT/DIV : 200mV
TIME/DIV : 500ns
RF signel waveform
C (DC voltage)
Tracking servo
Sled servo
ON
Tracking servo
Sled servo
OFF
Traverse waveform