Toshiba SD-2550A Service Manual page 43

Check IC502.
Lens cleaning.
Replace pickup head.
Check wiring for
pickup head.
Check pins 13, 14
and 15 of IC502
serial bus.
Check peripheral
circuits of IC502,
Q501, Q502.
DVD single (single-layer) disc
detection waveform
TP405 FE signal
TP503 RFSB signal
V : 500 mV/div
H : 2 ms/div
Fig. 1-3-6
Disc kind misjudgement
(Initial setting is NG.)
Are FE and RFSB
N
signals for each disc normal?
Check peripheral
circuit of IC605.
Fig. 1-3-4
3
Check laser operating current.
lop I min
Check laser current.
I min lop
Y
Check FE and RFSB signal
To turn on each laser diode forcibly, press the following buttons on the remote controller.
DVD LD: ZOOM, 0, 3, 0, ZOOM
CD LD: ZOOM, 0, 3, 1, ZOOM
After checked the laser current, press POWER or OPEN/CLOSE button to turn it off.
CAUTION
The laser ray emitting out from the pickup head is very harmful to your eyes.
Keep your eyes from the objective lens at least 300mm distance during the pickup head operating.
When you perform solder removal work, please turn OFF a set power supply and perform the
ground of human body and a tool.
Fig. 1-3-5
DVD dual (dual-layer) disc
detection waveform
1.65V
Fig. 1-3-7
2-2
Y
DVD Iop = Voltage between (E559 and E591) /10 9
CD Iop = Voltage between (E536 and E591) /10 9
lop I max
I max
lop 200 mA
Y
Check solder removal
of the short land for
laser diode protection.
V : 500 mV/div
H : 2 ms/div
1-39
Laser operating current
min typ max
DVD Iop
20mA 35mA 60mA
20mA 45mA 80mA
CD Iop
N
Replace pickup
mechanism.
CD disc
detection waveform
V : 500 mV/div
H : 2 ms/div
Fig. 1-3-8