HCD-DX30/RG40
SECTION 5
ELECTRICAL ADJUSTMENTS
FM Tuned Level Adjustment
CD SECTION
FM RF Signalgenerator
75 Ω coaxial
Carrier frequency : 98 MHz
Modulation | : AUDIO 1 kHz, 75 kHz |
| deviation (100%) |
Output level | : 28 dB (at 75 Ω open) |
set
FM ANTENNA terminal (TM101)
Note :
1.CD Block is basically designed to operate without adjustment. Therefore, check each item in order given.
2.Use
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
Procedure:
1.Supply a 98 MHz signal at 28 dB from the ANTENNA terminal.
2.Tune the set to 98 MHz.
3.Adjust RV101 to the point (moment) when the TUNED indicator will change from going off to going on.
Adjustment Location: MAIN board
Null Adjustment
Oscilloscope
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 (D GND) by lead wire. |
FM RF Signalgenerator
75 Ω coaxial
Carrier frequency : 98 MHz
Modulation | : AUDIO 1 kHz, 75 kHz |
| deviation (100%) |
Output level | : 60 dB (at 75 Ω open) |
set
FM ANTENNA terminal (TM101)
4. | Turn Power switch on. |
5. | Load a disc |
| consequence of open and close the disc tray, actuate the focus |
| search) |
6. | Confirm that the oscilloscope waveform |
| symmetrical between A and B. And confirm peak to peak level |
| within 4 ±1 |
symmetry
Procedure:
1.Supply a 98 MHz signal at 60 dB from the ANTENNA terminal.
2.Tune the set to 98 MHz.
3.Measure voltage between pin 21 and pin 23 of IC 101. Adjust T101 ubtil the voltage becomes 0 V.
Adjustment Location: MAIN board
Adjustment Location
[MAIN BOARD] Component side
T101:NULL
RV101:FM TUNED LEVEL
T101
RV101
RV661:TAPE SPEED
T102
IFT101
RV661
A
within 4
B
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
oscilloscope
BD board
TP(RF)
TP(VC)
Procedure :
1.Connect oscilloscope to TP (RF).
2.Connect between TP (AGCCON) and TP (D GND) by lead wire.
3.Turned Power switch on.
4.Load a disc
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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