Sony CDP-CX235 - Tracking Servo; Spindle Servo

37
Tracking Servo
The tracking servo is turned on after focus is found (FOK = HIGH). This
servo results in a periodic track correction signal that looks like about
400mV of noise at the TE test point.
339 , U & S
ch2
ch1
ch1: pkpk= 1.44 V
CH1 1.00 V= STOP
CH2! 200mV= MTB1.00ms PKD ch1+
1
2
Normal CD Playback
Channel Signal Name Location
1 RFO test point IC103/pin 16
2 TE test point IC103/pin 13
Time base = 1msec/div
Scope ground is taken at Vc (IC103/pin 12)
When the tracking loop is open, the laser is no longer following the data
track. In the following scope shot, the RFO waveform in channel 1 shows
the laser is seeing alternate areas of RF data (teeth) and no data (gaps).
Channel 2 shows there is TE correction signal generated from IC103/pin
13, but it is not reaching the tracking coil for correction.
PM3394,
FLUKE
&
PHILIPS
ch2
ch1
ch1: pkpk= 1.28 V
CH1 1.00 V= STOP
CH2! 500mV= MTB1.00ms PKD ch1+
1
2
Defective Tracking Servo Waveforms
Channel Signal Name Location
1 RFO test point IC103/pin 16
2 TE test point IC103/pin 13
Time base = 100msec/div
Scope ground is taken at Vc (IC103/pin 12)
Spindle Servo
Although the spindle motor has started when focus was found (FOK =
HIGH), its lock onto the data does not occur until about 800msec later. At
that time the LOCK signal goes HIGH.
PM3394,
FLUKE
&
PHILIPS
ch4
ch3
ch2
ch1
CH1 2.00 V=
CH2!5.00 V=
CH3!5.00 V=
CH4!5.00 V= CHP MTB 200ms- 2.28dv ch1+
1
2
3
4
T
CD Playback Starting
Channel Signal Name Location
1 RFO IC103/pin 16
2 FOK test point IC101/pin 24
3 LOCK test point IC101/pin 25
4 C2PO test point IC101/pin 19
Time base = 200msec/div
Scope ground is taken at Vc (IC103/pin 12)
At this time, the RFO signal should be at least 1Vp-p (1.2Vp-p = normal)
and the RFO waveform should be straight on top and bottom (no drop-
outs).
Once the LOCK test point goes HIGH, the servos are all working and
audio should output if that processing within IC101 is OK.