Sony LBT-A590 Service Manual page 122

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.
AY
S Curve Check
oscilloscope
BD board
TP (FE) O+—0F
TP (VC) Owt—0-
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 symmetrical
between A and B. And confirm peak to peak level within
3+1 Vp-p.
S-curve waveform symmetry
4
7 E: within 3+ 1 Vp-p
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—t—j°+
TP (vc) Ot]?
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 :
Clear RF signal waveform means that the shape "€>" can be
clearly distinguished at the center of the waveform.
VOLT/DIV : 200mV
TIME/DIV :500nS
RF signal waveform
NR
f,9,' KK} 4,
AVR ANH q
wi
level : 1.2325 Vp-p
1
IHN
IN
A
AY
WW LAMA
0oo
E-F Balance Check
oscilloscope
BD board Cy
TP (TE)
igang pai
TP (VC) oOw—0-
Procedure :
1. Connect test point TP (ADJ) on MAIN board to ground and
TP(TEI) 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 OV, and check this level.
YR
Traverse waveform
symmetry
level: 2+1Vpp
6. Remove the lead wire connected in step 1.
RF PLL Free-run Frequency Check
Procedure :
1, Connect frequency counter to test point (PLCK) with lead
wire.
sae frequency counter
TP (PLCK) oe
2. Turned Power switch on.
3. Confirm that reading on frequency counter is 4.3218MHz.