Toshiba SD-2050 Service Manual page 62

7
Disc playback is NG (DVD).
Is PLL locked?
(Refer to waveforms.)
Y
Check signal process
system following to IC402.
Check peripheral circuits of
IC401 and IC604.
DVD RF signal
DVD RF signal
Pin 45 (TP502) of IC502
V : 500 mV/div
H : 50 ns/div
Fig. 1-3-17
CD RF signal
CD RF signal
Pin 45 (TP502) of IC502
V : 500 mV/div
H : 100 ns/div
Fig. 1-3-18
N
N
Fig. 1-3-16
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?
Y
Does RF output
higher than 1.5 V(p-p)
develop at pin 45 (TP515)
of IC502?
Y
Pin 57 of IC502 = 2.4V
Pin 58 of IC502 = 3.0V
Y
Check peripheral circuits
of IC502 and IC401.
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.
DVD playback waveform
CH1 : TP515 DVDRF 500 mV/div
CH2 : TP511 DVDPLCK 5 V/div
50 ns/div
Fig. 1-3-19
CD playback waveform
CH1 : TP502 CDRF 500 mV/div
CH2 : TP409 CDPLCK 5 V/div
100 ns/div
Fig. 1-3-20
N
Check peripheral circuits
of IC401 and IC604.
N
Check IC502.
Lens cleaning.
Pickup mechanism
replacement
DVD RF signal
Pin 45 (TP502) of IC502
DVD PLCK
Pin 117 (TP409) of IC401
CD RF signal
Pin 45 (TP502) of IC502
CD PLCK
Pin 117 (TP409) of IC401