Toshiba SD-2550A, Руководство по обслуживанию

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1-43
Disc playback is NG (DVD).
Is PLL locked?
(Refer to waveforms.)
Check signal process
system following to IC402.
Check peripheral circuits
of IC401 and IC605.
Does pulse of
L = 1.65V and H = 3.3V
develop at pin 131 and
L = 0V and H = 1.65V
develop at pin 132
of IC401?
Does RF output
higher than 1 V(p-p)
develop at pin 30 (TP502)
of IC502?
Check IC502.
Lens cleaning.
Pickup mechanism
replacement
Check peripheral circuits of
IC401 and IC605.
Pin 43 of IC502 = 2.4V
Pin 44 of IC502 = 3.0V
Check peripheral circuits
of IC502 and IC401.
7
Y
N
N
N
N
Y
Y
Y
DVD RF signal
Pin 30 (TP502) of IC502
V : 500 mV/div
H : 50 ns/div
DVD RF signal
DVD RF signal
Pin 30 (TP502) of IC502
DVD PLCK
Pin 117 (TP409) of IC401
CH1 : TP502 DVDRF 500 mV/div
CH2 : TP409 DVDPLCK 5 V/div
50 ns/div
DVD playback waveform
CD RF signal
Pin 30 (TP502) of IC502
V : 500 mV/div
H : 100 ns/div
CD RF signal
CD RF signal
Pin 30 (TP502) of IC502
CD PLCK
Pin 117 (TP409) of IC401
CH1 : TP502 CDRF 500 mV/div
CH2 : TP409 CDPLCK 5 V/div
100 ns/div
CD playback waveform
Fig. 1-3-16
Fig. 1-3-17
Fig. 1-3-19
Fig. 1-3-18
Fig. 1-3-20
PLL works as a servo loop to generate a clock signal for reading RF
signal binary data. With the PLL locked, the eye pattern is identified
clearly when triggered with the read clock PLCK.