Sharp 21C-FX1G Посібник з експлуатації - Сторінка 8

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1. Specifications

PIF ADJUSTMENT

No. Adjusting point

Adjusting procedure/conditions

Tuner IFT

1. Get the tuner ready to receive the CH. E - 9

( PRESET )

signal,but with no signal input.

Adjust the PLL data.

2. Connect the sweep generator's output cable to

the tuner antenna. ( RF SWEEP )

3. Adjust the sweep generator's to 80dBµV.

4. Connect the response lead ( use LOW IMPED-

ANCE probe with wave detector ; see Fig.1 ) to

the tuner's

IF output terminal. ( This terminal

must have the probe alone connected ).

5. Set the RF AGC to 0 - 6 V with no saturation with

the waveform.

6. Adjust the tuner IF coil to obtain the waveform as

shown in Fig. 2.

Note: Be sure to keep the tuner cover in posi-

tion during this adjustment.

RF-AGC

1. Receive "PAL COLOUR BAR" signal.

» Signal Strength: 54 ± 1 dBµV (75 ohm open)

TAKE OVER

POINT AD-

JUSTMENT

2. Connect the oscilloscope to TP201 (Tuner's AGC

(I2C BUS

Terminal) as shown in Fig. 3.

CONTROL)

Oscilloscope

0.1V

—

Bias box

—

» Bias box: About 4.5 V

Fig. 3

3. Call "AGC" mode in service mode. Adjust the

"AGC" bus data to obtain the Tuner output pin

drop 0.1V below maximum voltage.

4. Change the antenna input signal to 63~67dBµV,

and make sure there is no noise.

5. Turn up the input signal to 90~95 dBµV to be sure

that there is no cross modulation beat.

Waveform and others

10k

1n60

1000p

Oscilloscope

100k

1000p

75ohm

Fig.1

E-9 CH

-1.5+/-0.8dB

Fig.2

Note: For the 50 ohm signal

strength gauge, when not

using

50/75

impedance

adapter, signal strength is

1dB

V(75 ohm open), in-

stead of 54

1dB

V (75 ohm

open).

TP201

Precaution: The loss of using

impedance adapter.

TV Set

8-1

SIF (NICAM/IGR) ADJUSTMENT

No. Adjusting point

Adjusting procedure/conditions

VCO COIL

1. Receive "PAL colour bar" signal.(E-69)

T2300

(Set AFT ON 855.25MHz frequency).

2. Connect DC Voltmater to TP202 (MAIN BOARD

TEST POINT).

3. Check and turn T2300 counter-clockwise (Left)

to 0V and then turn it clockwise (Right) until TP202

IF OUT

become 5V.

After that, turn T2300 counter-clockwise (Left) until

TP202 became 2.5 ± 0.1Vdc.

* UNIT BOARD ADJUSTMENT

Vcc

IF Input Frequency 38.9MHz ± 0.1V

Adjust T2300 unit TP2300 (NICAM BOARD TEST

POINT) become 2.5 ± 1.0V

Check after assembly NICAM BOARD

Test point: TP202 (IN MAIN BORD).

Preset selected receptiion frequency (AFT OFF)

Check Voltage 2.5 ± 1.0Vdc.

Precaution: The Vcc, fo and other factors are

Waveform and others

*For model

21C-FX5 and 21C-FX8

5V ± 0.1V

considered in theunit board of

the 1.0V tolerance which differ

from the adjustment accuracy.

8-2