20
FM Tuned Level Adjustment
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
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
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)
FM ANTENNA terminal
(TM601)
set
FM RF SSG
75
Ω
coaxial
Carrier frequency : 98 MHz
Modulation : AUDIO 1 kHz, 75 kHz
deviation (100%)
Output level : 60 dB (at 75 W open)
FM ANTENNA terminal
(TM601)
set
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 10M
Ω
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
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.
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
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.
BD board
Oscilloscope
TP(FEO)
TP(VC)
symmetry
S-curve waveform
within 4
±
1Vp-p
A
B
TP(RF)
TP(VC)
BD board
oscilloscope
T601
RV611
RV351
RV354
RV304
RV303
RV302
RV352
RV353
RV301
CN301
CN304
CN302
CN303
1
3
NULL
FM TUNED LEVEL
Summary of Contents for HCD-VX77
Page 39: ...HCD VX77 VX77J 39 39 7 14 SCHEMATIC DIAGRAM POWER AMP SECTION ...
Page 43: ...HCD VX77 VX77J 43 43 7 18 SCHEMATIC DIAGRAM LEAF SW SECTION ...
Page 45: ...HCD VX77 VX77J 45 45 7 20 SCHEMATIC DIAGRAM DRIVER SECTION See page 58 for IC Block Diagrams ...
Page 47: ...HCD VX77 VX77J 47 47 7 22 SCHEMATIC DIAGRAM TRANS SECTION ...
