Sony LBT-G3000 Service Manual page 15

CD SECTION |
Note:
1. CD Block basically constructed to operate without
adjustment. Therefore, check each item in order given.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicat-
ed.
3. Use the oscilloscope with more than 10MQ impedance.
4. Clean an objective 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
nh
TP (FE) Omg———0 +
TP VG) Gee =
Procedure :
1. Connect oscilloscope to test point TP (FE) on BD board.
2. Connect between test point TP (FEI) and TP (VC) by
lead wire.
3. Turned Power switch on.
4. Put disc (YEDS-18) in and turned Power switch on again
and actuate the focus search. (Actuate the focus search
when disc table is moving in and out.)
5. Check the oscilloscope waveform (S-curve) is symmetri-
cal between A and B. And confirm peak to peak level
within 3+1Vp-p.
symmetry
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S-curve waveform
within 3+ 1Vp-p
6. After check, remove the lead wire connected in step 2.
Note: e@Try to measure several times to make sure that
the ratio of A: B or B: A is more than 10: 7.
e Take sweep time as long as possible and light up
the brightness to obtain best waveform.
RF Level Check
oscilloscope
BD board
nn,
TP (RFO) O«—~o +
TP(VG). -gegscile pc
Procedure :
J. Connect oscilloscope to test point TP (RFO) on BD
board.
2. Turned 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 "©"
can be clearly distinguished at the center of the
waveform.
VOLT/DIV: 200mV
RF signal waveform TIME/DIV : 500nS
WN
i 00
\ sN
CA
E-F Balance Check
level: 1.2 £328 Vp-p
|.
oscilloscope
BD board
———
TP (TE) O«—~o +
TPWO): gage tg =
Procedure :
1. Connect test point TP (ADJ) to ground and TP (TED to
TP (VC) with lead wire.
Connect oscilloscope to test point TP (TE) on BD board.
Turned Power switch on.
Put disc (YEDS-18) is and playback.
Confirm that the oscilloscope waveform is symmetrical
on the top and bottom in relation to 0V, and check this
level.
oF wN
Traverse waveform
symmetry
level: 2+1Vp-p
6. Remove the lead wire connected in step 1.