Electrical Check - Sony CDX-T70MX Service Manual

ELECTRICAL CHECK

Note:
1. This check is performed with the set placed horizontally.
2. Power supply voltage: DC14.4 V (more than 3 A).
3. Be sure to use the disc "YEDS-18" parts code: 3-702-101-01, but only
when indicated.
4. Use a master unit that supports SONY bus system.
Connection:
power supply
(DC 14.4 V)
master unit
+
GND
BUS cable
compact disc changer
SECTION 4
FOCUS BIAS CHECK
Connection:
– RF Board (Component Side) –
oscilloscope
(AC range)
+
–
IC101
TP (RFAC) TP (VC)
Procedure:
1. Connect the oscilloscope to TP (RFAC) and TP (VC) on the
RF board.
2. Put the set into play mode by loading the disc (YEDS-18).
3. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
Note:
Clear RF signal waveform means that the shape "◊" can be clearly distin-
guished at the center of the waveform.
RF signal waveform
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
(10 : 1 probe in use)
level: 1.4
When observing the eye pattern, set the oscilloscope to AC range
and raise the vertical sensitivity so that it may be easily seen.
TRACKING OFFSET CHECK
Connection:
– RF Board (Component Side) –
oscilloscope
(DC range)
+
–
TP (TE)
IC101
TP (VC)
Procedure:
1. Connect the oscilloscope to TP (TE) and TP (VC) on the RF
board.
2. Put the set into play mode by loading the disc (YEDS-18).
[ AMS ]
3. Press the . > button on the master unit, and check
the traverse waveform*.
4. Confirm that the oscilloscope waveform is symmetrical on the
top and bottom in relation to 0 V dc, and check this level.
* Traverse waveform: This is the tracking error wave form appears
when crossing the track.
Traverse waveform
A
+ 0.3
Vp-p
0 V
– 0.4
B
A=B
traverse waveform
(100 track jump waveform)
17 17
VOLT/DIV: 500 mV
TIME/DIV: 2 ms
Center: 0 V
CDX-T70MX