FDL-PT222
SECTION 3
CIRCUIT ADJUSTMENTS
3-1.A BOARD ADJUSTMENT
[+4.5V ALIGNMENT (RV601)]
Using a digital voltmeter measuring the voltage between JL32 (+4.5V) and JL33 (GND). Adjust RV601 to obtain the value shown below.
Standard Value = 4.45V± 0.05VDC
S601 position = UHF position
[+30.0V CHECK]
Check the voltage across JL29 (+30.0V) and JL33 (GND) .
Standard Value = 30.5V± 1.5VDC
[AUDIO OUTPUT CHECK]
[VIF.AFT COARSE ADJUSTMNT (T201, T202)]
[SETUP]
1.Set S601 on the A board to VHF position.
2.Apply no signal to JL18 (RF).
3.Connect a 1 kΩ resistor between JL77 (+4.5V) and JL28 (RF AGC).
4.Apply a sweep signal across JL26 (IF) and JL27(IF GND). (Fig.
Note : Set the sweep signal for JL26 to
1.Feed the audio signal 1kHz 100% modulated.
2.Set RV501 to maximum.
3.Connect an oscilloscope between JL23 (SP) and JL15 (SP GND).
4.Check the waveform on the oscilloscope becomes the stan- dard value.
Standard Value =
SWEEP
MARKER
GENERATOR
fo=45.75MHz± 5kHz
ATT
75Ω 6dB
Fig.
0.01∝ F
JL26
3-2.T1 BOARD ADJUSTMENT
- T1 board - (Component side)
T201 T202
RV201
RV002
RV004 | TU101 |
RV001
[ADJUSTMNT]
1. Connect an oscilloscope between JL72 (VIDEO) and JL71 (A.GND) and apply an external voltage (MGC) to JL26 to obtain a waveform as shown in Fig.
Note : Align JL51 (MGC) external voltage for approximately a 1.0
2.Remove the external voltage (MGC) from JL51.
3.Connect an oscilloscope between JL31 (AFT) and JL30 (D.GND) and make a coarse adjustment of T201 so that wave- form is close to zero at the 45.75 MHz position.
4.Remove the 1 kilohm resistor connected between JL77 (+4.5V) and JL28 (RF AGC).
45.75MHz
0
Fig.
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