Circuit Adjustments - Sony FDL-PT222 Service Manual

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]
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 = 1.5V-2.8Vp-p
3-2.T1 BOARD ADJUSTMENT
- T1 board - (Component side)
T201 T202
RV201
RV002
RV004
RV001
SECTION 3

CIRCUIT ADJUSTMENTS

[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 k resistor between JL77 (+4.5V) and
JL28 (RF AGC).
4. Apply a sweep signal across JL26 (IF) and JL27(IF GND).
(Fig. 3-1)
Note : Set the sweep signal for JL26 to -30 5dBm. Keep the
distance to the ATT output JL26 as short as possible.
fo=45.75MHz 5kHz
[ADJUSTMNT]
1. Connect an oscilloscope between JL72 (VIDEO) and JL71
(A.GND) and apply an external
obtain a waveform as shown in Fig. 3-2 (make sure not to
clip the extremely short portion).Adjust T202 so that the po-
sition at 45.75 MHz is the lowest point.
Note : Align JL51 (MGC) external voltage for approximately
2. Remove the external voltage (MGC) from JL51.
TU101
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).
– 7 –
SWEEP
MARKER ATT
GENERATOR
75 6dB
Fig. 3-1
a 1.0 Vp-p. Make sure that the JL51 (MGC) external
voltage does not exceed 4.3VDC.
45.75MHz
0
Fig. 3-2
FDL-PT222
0.01 F
JL26
voltage (MGC) to JL26 to
1Vp-p