SHARP 21BS1
Manual de Servicio

21B-S1

PIF ADJUSTMENT
NO. Adjustment part 1 Tuner IFT (PRESET) Adjusting procedure and conditions 1. Get the tuner ready to receive the E-9 CH 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 IMPEDANCE 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 position during this adjustment. Fig. 2
Oscilloscope

PURITY ADJUSTMENT
Waveform and others NO. Adjustment part 1
10k 1n60 1000p IF OUT 100k 75ohm

Adjusting procedure and conditions 1. Receive the GREEN-ONLY signal. Adjust the beam current to ~700 µA (21")/~500 µA (14"). 2. Degauss the CRT enough with the degausing coil. Note: Follow the Job Instruction Sheet to adjust the magnetic field. Vertical Bv : +0.030 mT (0.30 gauss) Horizontal Bh : +0.020 mT (0.20 gauss) (Reference page 6.) 3. Maintain the purity magnet at the zero magnetic field and keep the static convergence roughly adjusted. 4. Observe the points a, b as shown in Fig. 4-1 through the microscope. Adjust the landings to A rank requirements. 5. Orient the raster rotation to 0 eastward. 6. Tighten up the deflection coil screws. » Tightening torque: 108 ± 20 N (11 ±2 kgf) 7. Make sure the CRT corners landing meet the A rank requirements. If not, stick the magnet sheet to correct it. Note: This adjustment must be done after warming up the unit for 30 minutes or longer with a beam current over 700 µA (21"). (For 14", the beam current should be over 500 µA). Note: Set the service mode by TP1001 & TP1002 (short) then press factory process R/C RGB key to change to RGB mono colour mode. * For the following colours press R/C RGB key to change.

Waveform and others

PURITY ADJ.

a

b

Fig. 1
E-9 CH

Fig. 4-1

P

C
-1.5+/-0.8dB

A

B A=B

2

RF-AGC TAKE OVER POINT ADJUSTMENT (I2C BUS CONTROL)

1. Receive "PAL COLOUR BAR" signal. » Signal Strength: 54 ±1 dBµV (75 ohm open) 2. Connect the oscilloscope to TP210 (Tuner�s AGC Terminal) as shown in Fig. 3.
Oscilloscope 0.1V + � Bias box + � » Bias box: About 4.5 V TV Set TP210

Note: For the 50 ohm signal strength gauge, when not using 50/75 impedance adapter, signal strength is 52 ±1 dBµV(75 ohm open), instead of 54 ±1 dBµV (75 ohm open). Precaution: The loss of using impedance adapter

Fig. 4-2 Rank "A" (on the right of the CRT)

8

A

B A=B

Fig. 4-3
Green only Blue only

Fig. 3 3. Call "AG" mode in service mode. Adjust the "AG" bus data to obtain the Tuner output pin drop 0.1 V 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.

Red only

Rank "A" (on the left of the CRT)

Signal colour screen cleared

* Press R/C RGB key for 1 second in NORMAL MODE, the colour will change to RGB mono colour mode.

8-1

8-2