Sharp VT-G14 Service Manual page 14

VT-G14
VT-G21
Ë Ë Ë Ë Ë PIF/AFT/AGC ADJUSTMENT(Continued)
3. RF AGC CUT-IN ADJUSTMENT: R265
1. Receive the "E-12CH" (PAL COLOUR BAR) sig-
nal.
» Field strength: 57 ± 1 dBµV (75 ohms open)
2. Connect the oscilloscope to TP201, as shown at
right.
3. Turn R265 to have the highest voltage.
4. Turn R265 slowly in the opposite direction until
the voltage goes down 0.1 V below the highest
level.
5. Adjust the signal level to 63 ~ 67 dBµV and make
sure there is no noise.
6. Now adjust the signal level to 90 ~ 95 dBµV and
make sure there is no chrominance modulation
beat.
Note : If a 50 ohm field strength meter is used
without a 50/75 impedance converter, set
the field strength to 55 ±1 dBµV. Pay atten-
tion to a loss that would be caused with
the converter.
Oscilloscope
+
0.1V
–
Bias box
+
–
14
TV Set
TP201
Bias box:About 6.5V
Fig. 4