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PD-M423, PD-M403
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
TPI, Pin
6(FCS. ERR)
(just the Power switch on)
10 ms/division
DC mode
@ Disc
None needed
[Procedure]
Verify the DC voltage at TP1, 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]
. Move the pickup to midway across the disc (R=35 mm) with the TRACK /MANUAL SEARCH FWD PtP. pp] or
REV KK. <klkey.
. Press the PGM (PROGRAM) key, then the PLAY/PAUSE [>/ []] key in that order to close the focus servo then the
spindle servo.
. Line up the bright line (ground) at the center of the oscilloscope screen and put the oscilloscope into DC mode.
. 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.
When
A2ZB,
When
A<B,
When there is a DC
When there is no DC
component
component
29
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