Electrical Block Checking - Sony LBT-A590 Service Manual

SECTION 3
ELECTRICAL BLOCK CHECKING
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
indicated.
Use the oscilloscope with more than 10MQ impedance.
Clean an object lens by an applicator with neutral detergent
when the signal lever is low than specified value with the
following checks.
BY
BD board
pein
TP(FE) o<n—lo+
TP(vc) O18
Procedure :
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 symmetrical
between A and B. And confirm peak to peak level within
341 Vp-p.
symmetry
S-curve waveform
6. After check, remove the lead wire connected in step 2.
Note : + Try to mesure several times to make sure than 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
"~—
TP(RFO) o~—o+
TP(VC) o*—~18=
Procedure :
1. 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 :
clearly distinguished at the center of the waveform.
VOLT/DIV : 200mV
TIME/DIV : 500nS-
i
level:
1.235 Vp-p
RF signal waveform
WO
ARR
NAAN
Se
(OC range)
BD board O
para
TP(RFO) Os—jo+
TP(VC)
Procedure :
1, Connect test point TP (ADJ) on MAIN board to ground and
TP(TED) to TP (VC) with lead wire.
Connect oscilloscpe to test point TP (TE) on BD board.
Turned 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 0Vdc, and check this level.
wRON
Traverse osilloscope
symmetry
level :2+1 Vp-p
6. Remove the lead wire connected in step 1.
RF Free-run Frequency Check
Procedure :
1. Connect frequency counter to test point (PLCK) with lead
ee frequency counter
BD board
ae coc
TP (PLCK) O*—j9+
q
™
2. Turned Power switch on.
3. Confirm that reading on frequency counter is 4.3218MHz.