SHARP SX80J7
Service Manual

PIF/AFT/AGC � DIGITAL COMB FILTER Y LEVEL ADJUSTMENT

3. AFT T204 DC voltage at TP201 [ Pin (1) of IC201] 1. DIGITAL COMB FILTER Y LEVEL ADJUSTMENT: R5467
6V this is not available, any signal above the level 1.0 Vp-p ± 0.05Vp-p).

Receive E-12CH (PAL signal. If 1. Input the PAL bar (100% white colour bar) signal to AV-IN terminal with a 75 ohm termination (input

E-5CH band is acceptable. 2. Connect the oscilloscope to TP5462 (pin (7) of connector YA). � Field strength: 55~80 dBµV 3. Adjust R5467 so that the Y signal (100% white) at TP5462 be 2.0 ± 0.1Vp-p. Make sure frequency is almost the same as 3.3V of received channel (± 30 kHz). Note: Make sure that the signal is linearly amplified overall. (The 100% portion should be kept intact.)

2. Using the channel setting control, make a fre-

quency of 224.25 MHz appear on screen. <Reference> Note voltage level for adjustment with the E-12CH signal. (AFT off)(If any other channel than E-12CH is To be adjusted to 2.0 Vp-p at TP5462 received, make its frequency on screen.) * Make sure above value is available after the adjustment No. 5. (See Page 12.)
DOWN A B' B B'' C UP

3. Turn T204 coil clockwise first to have 6V readInput (YB) (2): 2.0 V ± 0.1 Vp-p

ing and then counterclockwise to get 0.2 readOutput (YA) (7): 2.0 V ± 0.1 Vp-p Fig. 3 ing. * Turn core counterclockwise for UP diWithin range, adjust this coil to reach the volt-

� SOUND ADJUSTMENT
B' B''). Point A and C are rejectable.

rection, and clockwise for the DOWN direcage below. tion. Adjust the T204 core to point B (between 4. Adjust T204 so that DC voltage at the pin (1) of IC201 be 3.3 ± 0.2 V. (See Fig. 3.)

2

1. SUB SOUND ADJUSTMENT (I C bus adjustment)
0.04/-0.06 Vp-p 2. Set the volume control to MAX. 3. Connect VTVM probe to the S1 connector. (Pin 1: L-ch, 2: GND, pin 3: R-ch)
TV Set 4. Adjust sub-sound data so that VTVM should read following voltage. For the left channel. Fig. 4. Oscilloscope

4. RF AGC CUT-IN ADJUSTMENT: R226 1. Feed following signal to the AV terminal. Signal: 1 kHz, 1.76 Vp-p (terminated with a 10k ohm impedance),

1. Receive the E-12CH (PAL colour bar) signal.

� Field strength: 57 ± 1 dBµV (75 ohms open) Adjustment error: 8.0 ± 0.1 Vrms

2. Connect the oscilloscope to P201, as shown in
P201 Notes:

7
0.1V 3. Turn R226 to have the highest voltage.

� Bias box: About 6.5V

4. Turn R226 slowly in the opposite direction until

voltage goes down 0.1V below the highest level.

5. Adjust the signal level to 63-67 dBµV and make
Bias box 6. Now adjust the signal level to 90-95 dBµV and

� Spatializer off � In the S-Normal mode � S-VOL control at MAX position * Use an 8 ohm dummy load.

sure there are no noise.

2. NOISE MUTE CHECKING make sure there is no chrominance modulation +
1. Receive E-12CH "PAL colour bar" signal. 2. Turn up volume control to maximum and make sure sound is heard from speakers. Then put the unit in the no-signal state. 3. Be sure that the sound mute is effective.

beat.

Note: If a 50 ohm field strength meter is used with-

Fig. 4 4. Finally turn down the volume control minimum.

out a 50/75 impedance converter, set the field strength 55 ± 1dBµV. Pay attention to a loss that would be cause with the converter.

5. VIDEO DETECTION LEVEL ADJUSTMENT: R224

1. Receive "B/G SYSTEM PAL COLOUR BAR" signal (100% white colour bar). Set the S system to B/G. 2. Adjust R224 so that video output at the AV OUT terminal be 1.0 ± 0.05 Vp-p with a 75 ohm termination.

SX80J7

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