Sharp VT-3448X Service Manual page 13

3. RF AGC CUT-IN ADJUSTMENT : R216
1. Receive the "E-12CH" (PAL COLOUR BAR) sig-
Field strength: 57 +I dBpV (75 ohms open)
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Connect the oscilloscope to TP204, as shown at
2.
right.
3. Turn R216 to have the highest voltage.
4. Turn R216 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 dBpV and make
sure there is no noise.
6. Now adjust the signal level to 90 - 95 dB@/ 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 +I dBpV. Pay atten-
tion to a loss that would be caused with
the converter.
Oscilloscope
Bias box
13
TV Set
Bias box:About 6.5V
Fig. 4
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