SHARP 21E1RU
Manual de Servicio

ADJUSTMENT PRECAUTIONS: Make sure TV set is in "Normal Condition" before switch to Service Mode for adjustment.

PIF PURITY ADJUSTMENT

No. point Adjusting procedure/conditions Waveform and others

Tuner IFT Get tuner ready to receive CH. E 9 1 PURITY ADJ. 1. Receive GREEN-ONLY signal. Adjust the

( PRESET ) signal,but with no signal input. beam current to about 700 µA.

Adjust PLL data. 2. Degauss CRT enough with the degausing coil.
Oscilloscope IF OUT 75ohm 100k

2. Connect sweep generator�s output cable to 10k 1n60 1000p 3. Maintain purity magnet at the zero magnetic

a b

tuner antenna. ( RF SWEEP ) field and keep the static convergence roughly

3. Adjust the sweep generator�s to 80dBuV. adjusted. Connect response lead ( use LOW IMPED4. Observe the points a, b as shown in Fig. 4-1

ANCE probe with wave detector ; see Fig.1 ) through microscope. Adjust landing to the the tuner�s IF output terminal. ( This terminal Fig.1 rank A requirements. must have probe alone connected ). 5. Orient the raster rotation to 0 eastward. E-9 CH

Fig. 4-1

5. Set RF AGC to 0 6 V no saturation with 6. Tighten up the deflection coil screws.
P C
-1.5+/-0.8dB

the waveform. » Tightening torque: 108 20 N (11 ± 2 kgf) shown in Fig. 2. rank requirements. If not, stick the magnet sheet A

6. Adjust tuner IF coil to obtain waveform as 7. Make sure CRT corners landing meet the A

to correct it. longer with a beam current over 700 µA.
A = B 2 RF-AGC 1. Receive "PAL COLOUR BAR" signal. Note: For the 50 ohm signal

Be sure to keep the tuner cover in position Fig.2 Note: This adjustment must be done after

during this adjustment. warming up the unit for 30 minutes or B

* For the following colours press R/C RGB key to

TAKE OVER » Signal Strength: 57 ± 1 dBµV (75 ohm open) strength gauge, when not change. POINT AD2. Connect the oscilloscope to TP201 (Tuner AGC u s g 0 / 7 5 i m p d a n c e 4-3 Fig. 4-2 JUSTMENT Terminal) as shown in Fig. 3. adapter, signal strength is (I C BUS (on52±1dBµV(75 rightohm ofopen), theinCRT)2 open). + TP201

Rank "A"

Oscilloscope CONTROL) stead of 57±1dBµV (75 ohm Blue-only Red-only

Green-only

7
7-1 7-2

0.1V Precaution: The loss of using

� impedance adapter

+

Bias box TV Set Signal-colour A screen cleared

�

B A = B

» Bias box: About 4.5 V

Fig. 3

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

4. Change the antenna input signal to 63~67dBµV, (on left of the CRT)

"AGC" bus data to obtain the Tuner output pin drop 0.1V below maximum voltage. Rank "A"

and make sure there is no noise.

5. Turn up the input signal 90~95 dBµV to be sure * Press R/C RGB key for 1 sec-

that there is no cross modulation beat. ond in NORMAL MODE, the

colour will change to RGB mono colour mode. The TEXT "R. G. Cy" Key can be directly use to change to other colours screen.

21E1-RU