Sony CDP-M72 - 2, Electrical Block Checking

| CDP-M72
SECTION 2
ELECTRICAL BLOCK CHECKING
Note :
1. CDBlock basically constructed to operate without adjustment.
Therefore, check each item in order given.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use the oscilloscope with more than 10OMQ impedance.
4. Clean an object lens by an applicator with neutral detergent
when the signal level is low than specified value with the
following checks.
S Curve Check
oscilloscope
BD board
a“
TP (FEQ) ©
TP (VC)
Procedure :
1. Connect oscilloscope to test point TP (FEO) on BD board.
2. Connect between test point TP (FES) and TP (VC) by lead wire.
3. Turned Power switch on and actuate the focus serch. (actuate
the focus serch when disc table is moving in and out.)
Check the oscilloscope waveform (S curve) is symmetrical
between A and B. And confirm peak to peak level within
341 Vp-p.
4.
S curve waveform symmetry
within 3£1Vp-p
5. After check, remove the lead wire connected in step 2.
Note: » Try to measure several times to make sure that the
ratio of A: B or B: A is more than 10: 7.
° Take sweep time as long as possible and light up the
brightness to obtain best waveform.
RF Level Check
oscilloscope
BD board
a
TP (RFQ) ©
TP (VC) ©
Procedure :
1. Connect oscilloscope to test point TP (RFO) on BD board.
2. Turn Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.
Note :
Clear RF signal waveform means that the shape “ 0” can be clearly
distinguished at the center of the waveform.
VOLT/DIV : 200mV
RF RY waveform TIME/DIV : 500nS
RY
NH
Ve )
ANY yy WN mee
WHINY | 12222 veer
E-F Balance Check
oscilloscope
BD board
TP (TEO) ©
TP (VC) ©
Procedure :
1. Connecttest point TP (ADJ) to ground and TP (TES)to TP(VC)
with lead wire. ;
Connect oscilloscope to test point TP (TEO) on BD board.
Turn Power switch on.
Put disc (YEDS-18) in and playback.
Confirm that the oscilloscope waveform is symmetrical on the
top and bottom in relation to OV, and check this level.
VPwh
Traverse oscilloscope
i I" |
symmetry
Level : 2£1Vp-p
6. Remove the lead wire connected in step 1.