Circuit Adjustments; A Board Adjustment; T Board Adjustment - Sony FDL-PT22/JE Service Manual

3-1. A BOARD ADJUSTMENT

+4.5V ADJUSTMENT
Measure the voltage between JL32 (4.5V) and JL33 (GND) with a
digital voltmeter, and adjust RV601 so that the voltage will be as
follows:
<Specification>
4.45 0.05VDC
S601: UHF position
CONFIRMATION OF +30V
Measure the voltage between JL29 (30V) and JL33 (GND) with a
digital voltmeter, and adjust RV601 so that the voltage will be as
follows:
<Specification>
30.5 1.5VDC
CONFIRMATION OF AUDIO OUTPUT
(1) Input 1kHz voice, 100% modulation from sound generator.
(2) Make RV501 MAX.
(3) Connect the probes of an oscilloscope to JL23 (SP) and JL15
(SP GND).
(4) Check the waveform on the oscilloscope, and make sure that it
is within the standard.
<Specification>
1.5 - 2.8Vp-p
SECTION 3
CIRCUIT ADJUSTMENT

3-2. T BOARD ADJUSTMENT

- T BOARD - (COMPONENT SIDE)
ROUGH ADJUSTMENT OF VIF.AFT
(1) Preparation
Set S601 in the VHF position.
Make JL18 (RF) signal-less
Insert 1k between JL77 (4.5V) and JL28 (RF AGC).
Input a sweep signal to the section between JL26 (IF) and JL27
(IF GND).
fo
Note:
(2) Insert the output between JL72 (VIDEO) and JL71 (A.GND)
to an oscilloscope, and apply external voltage (MGC) to JL51
so that the waveform shown in Fig.3-2 will appear (the mini-
mum section should not clip). Adjust T202 so that the position
of 45.75MHz will be the lowest.
Note:
– 8 –
RV004
RV201
TU101
Sweep signal
ATT
45.75MHz } 5kHz 75 ¶ 6dB
Fig.3-1
The sweep signal level should be -30 5dBm at JL26.
The distance between the ATT output and JL26
should be as short as possible.
This portion should be approx. 1.0Vp-p when exter-
nal voltage is applied to JL51 (MGC).
The external voltage applied to JL51 (MGC) should
not exceed 4.3VDC.
RV001
RV002
0.01 F
JL26