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WF-CD77H/E
Ot 1 BW)
©
3. Servo Unit
Since the adjusting procedure differs from that described in "ADJUSTMENT
PROCEDURES
OF AUDIO
PRODUCTS',
refer to the
Service Manual.
All the semivariable resistors must be set in the mechanical center position.
Test Stage
Adjusting Parts
| Value/Adjusting Method
li Instrument Connection
|
Test Mode 0
| Focus offset
VR702
| 0 + 30 mV
Pin 1 and Pin 2 of CNP701
|
Tracking offset
VR707
| 0 + 30 mV
Pin 3 and Pin 4 of CNP701
|
Test Mode 1 (Confirmation of laser lighting)
After loading the disc, set to Test Mode 2 (focus servo ON)
Test Mode 3 (Spin Servo ON)
Tracking error balance
VR701
* 1
| Pin8(1/2Vcc) and pin3 (Ground) of TP1
Test Mode 4 (Tracking Servo ON)
F
|
Adjust
to
obtain
clear
and
max.
Focus balance
VR704
amplitude
of
eye
pattern
(more
Pin1 of TP1 and pin2 (ground) of TP1
than 0.54 Vp-p) and min. jitter.
:
Adjust to obtain the same waveform
Pin 6 (CH1) and pin 7 (CH2) of TP1
pacts odin
uRgDS
| on CH1 and CH2. >2
and ground
:
:
Adjust to obtain the same waveform
Pin 4 (CH1) and pin 5 (CH2) of TP1
Tracking gain
VR703
| on CH1 and CH2. 3
and ground
*1
Adjust to obtain vertically symmetric waveform (Fig. 20-1) with respect to the reference DC level. The reference level is 1/2 Vcc
—20mvV (approx. 2.5 V).
*2 Input oscillation frequency:
1.3 kHz, 300 mV rms
*3 Input oscillation frequency:
1.5 kHz, 300 mV rms
Symmetrical
up and down
Measuring
the DC level
Figure 20—1
pn Poo
VR704
VR705
1
9
VR703
VR7O1
VR7Q2
VR7O07
cnp7o1 LI
l
Ic701
"TT
6
Cp
FW.
BR
Figure 20-2
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