Advertisement
PD-S703
1. Focus Offset Verification
@ Objective
Verify the DC offset for the focus error amp.
@ Symptom when out of | The model does not focus in and the RF signal is dirty.
adjustment
@ Measurement instru-
| Connect the oscilloscope to
@ Player state
Test mode, stopped
ment connections
TP1, Pin
6(FCS. ERR)
(just the Power switch on)
[Settings] _SmV/division
@ Adjustment location | None
10 ms/division
[Procedure]
Verify the DC voltage at TP!, Pin 6 (FCS. ERR) is 0 + 50 mV.
Note : If the specified values cannot be obtained or no adjustment is possible by performing the
verifications or adjustments described in adjustment items 1 — 4, the pickup block may be defective.
2. Tracking Error Balance Verification
@ Objective
To verify that there is no variation in the sensitivity of the tracking photo diode.
@ Symptom when out of | Play does not start or track search is impossible.
adjustment
@ Measurement instru-
| Connect the oscilloscope to
@ Player state
Test mode, focus and spindle servos
ment connections
TP1, Pin
2(TRK. ERR). This
closed and tracking servo open
connection may be via a low
pass filter.
@ Adjustment location
{| None
[Settings]
50 mV/division
5 ms/division
DC mode
[Procedure]
1. Move the pickup to midway across the disc (R=35 mm) with the TRACK / MANUAL SEARCH FWD pt - Pp or
REV I<kl- <kl key.
2. Press the OUTPUT SELECTOR key, then the PLAY [> key in that order to close the focus servo then the spindle
servo.
.
3. Line up the bright line (ground) at the center of the oscilloscope screen and put the oscilloscope into DC mode.
4. Supposing that the positive amplitude of the tracking error signal at TP1, pin 2 (TRK ERR) is (A) and the negative
amplitude is (B), the following expression is satisfied.
-B
When
A2ZB,
"Ee
*
B-A
When
A<B,
x
=A
Cc
When there is a DC
When there is no DC
component
component
Advertisement
