Analog Test Signal Amplitude Adjustment - Sony VPH-G90U Service Manual

5-2-3. Analog Test Signal Amplitude
Adjustment
1. Press the GAIN key to output the analog test signal.
2. Connect an oscilloscope to pin 4 of IC208 on the BA
board.
3. Adjust RV200 on the BA board so that the level of
analog signal meets the following specification.
Specification: B = 0.7 ±0.02 V
5-2-4. ABL Adjustment
1. Receive the white signal.
2. Set the CONTR, BRIGHT, and GAIN to the maximum
position.
3. Connect a digital voltmeter to base of Q813 on the BA
board. Adjust RV800 so that the voltage is _3.34
± 0.05V.
VPH-G90E/G90U/G90M
5-3. CAR/CAG/CAB BOARDS
5-3-1. Preparation Before Adjustments
1. Input the following signal.
Specification
B
2. Remove the CAR/CAG/CAB boards and CDR/CDG/
CDB board in sequence, and connect it back through
the extension board.
5-3-2. Pedestal Level Adjustment
1. Connect an oscilloscope to TP511.
2. Adjust the pedestal level by RV145.
5-3-3. CRT Protector Adjustment
1. Connect a variable current source (3.5 mA to 4.5 mA)
between the cathode terminal (pin 8 of CRT socket) of
the CBR (CBG and CBB) board and B +12 V line of
the CDR (CDG and CDB) board.
2. Connect a pull-up resistor (4.7 kZ) between pin 3 of
CN244 (CN264 and CN284) and +5 V line of the CDR
(CDG and CDB) board, then connect an oscilloscope to
it.
3. Gradually raise the output of the variable current
source, and adjust RV965 of the CAR (CAG and CAB)
board so that the waveform on the oscilloscope changes
from "High" to "Low" level at 3.9 ± 0.1 mA.
ADJUSTMENT
fH: 64 kHz
fV: 60 Hz
Amplitude: 0.7 ± 0.01 V
Sync: off
V
Pedestal
2 ±0.05 V
GND
0.7 V p-p
5-3