Sony HCD-VX99 Service Manual page 20

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FM Tuned Level Adjustment
FM RF SSG
75 Ω coaxial
Carrier frequency : 98 MHz
Modulation : AUDIO 1 kHz, 75 kHz
deviation (100%)
Output level : 28 dB (at 75 W open)
Procedure:
1. Supply a 28 dB 98 MHz signal from the ANTENNA terminal.
2. Tune the set to 98 MHz.
3. Adjust RV611 to the point (moment) when the TUNED
indicator will change from going off to going on.
Adjustment Location: MAIN board
Null Adjustment
FM RF SSG
75 Ω coaxial
Carrier frequency : 98 MHz
Modulation : AUDIO 1 kHz, 75 kHz
TE
L 13942296513
deviation (100%)
Output level : 60 dB (at 75 W open)
Procedure:
1. Supply a 60 dB 98 MHz signal from the ANTENNA terminal.
2. Tune the set to 98 MHz.
3. Measure voltage between pin 21 of IC 601. Adjust T601 ubtil
the voltage becomes 0 V.
Adjustment Location: MAIN board
Adjustment Location
[MAIN BOARD] Component side
NULL
FM TUNED LEVEL
T601
RV611
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set
FM ANTENNA terminal
(TM601)
set
FM ANTENNA terminal
(TM601)
CN304
CN301
3 1
RV301
RV352
CN302
RV302
RV353
RV303
RV351
CN303
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RV304
i
RV354
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8
CD SECTION
Note :
1. CD Block is basically designed 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 an oscilloscope with more than 10MΩ impedance.
4. Clean the object lens by an applicator with neutral detergent
when the signal level is low than specified value with the
following checks.
S-Curve Check
BD board
TP(FEO)
TP(VC)
Procedure :
1. Connect oscilloscope to TP (FEO).
2. Connect between TP (FEI) and TP (VC) by lead wire.
3. Connect between TP (AGCCON) and TP (GND) by lead wire.
4. Turn Power switch on.
5. Load a disc (YEDS-18) and actuate the focus search. (In
consequence of open and close the disc tray, actuate the focus
search)
6. Confirm that the oscilloscope waveform (S-curve) is
symmetrical between A and B. And confirm peak to peak level
within 4 ±1 Vp-p.
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3 6 7 1 3
S-curve waveform
7. After check, remove the lead wire connected in step 2 and 3.
Note : • Try to measure 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
BD board
TP(RF)
TP(VC)
Procedure :
1. Connect oscilloscope to TP (RF).
2. Connect between TP (AGCCON) and TP (GND) by lead wire.
3. Turned Power switch on.
4. Load a disc (YEDS-18) and playback.
5. Confirm that oscilloscope waveform is clear and check RF signal
level is correct or not.
6. After check, remove the lead wire connected in step 2.
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Oscilloscope
1 5 0 5 8 2 9 9 4
symmetry
A
within 4 ±1Vp-p
B
oscilloscope
m
co
9 9
2 8 9 9