Panasonic TC-20B10P AFT Adjustments, AGC-RF Adjustments, Noise Level Adjustments, Verification

Service Adjustments and Calibrations TC-14B10P / TC-20B10P

CALIBRATION OF VIDEO IF ( continuing)

1- PREPARATION

2.1- Connect the VIF generator positive output cable to TPE33 and the negative to ground.

2.2- Connect the VIF detector positive output cable to TPE13 and negative to ground.

2.3- Connect the +9V power source positive to pin 3 of IC851 and negative to ground.

2.4- Connect the +4V power source positive in series with 1KΩ resistor to pin 63 of IC601 and negative to ground.

2.5- Connect the polarization of AGC with positive to TPE21 (IF AGC) and negative to the ground.

2.6- Enter Serviceman Mode.

2- ADJUSTMENTS

3.1- Calibrate monitor to 200mVp-p

3.2- Decrease the VIF generator output to minimum signal. 3.3- First, turn on the instruments and after that, the power

sources.

3.4- Adjust bias AGC to obtain maximum gain.

3.5- Adjust the VIF generator output to obtain 200mVp-p at the monitor.

3.6- Increase 20dB to VIF generator output and adjust the Bias AGC to obtain 200mVp-p at the monitor

3.7- Confirm that the level of CC (42,17 MHz) and PC ( 45,75 MHz) are within the especificated below.

ZERO↓BEAT

	42,75	45,00
200m Vp-p
	CC 42,17	PC 45,75
	45 ± 15%	45 ± 15%
	41,65
39,75	41,25	47,25

AFT ADJUSTMENTS

1- REQUIRED EQUIPMENTS

1.1- Oscilator CW 45,75 MHz

1.2- VIF detector

1.3- Digital multimeter

1.4- Short Jumper

2- PREPARATION

2.1- Disconnect the signal from the antenna terminal

2.2- Connect the multimeter between TPE29 and ground

2.3- Connect the CW oscilator using VIF detector between TPE33 and ground

2.4- Adjust the CW oscilator output to 90+-5dBu (75Ω open).

2.5- Position the DAC AFT in “80H”.

3- ADJUSTMENTS

3.1- Adjust AFT using coil L167 until the voltage below

(*)is obtained at TPE29.

(*)4,0±1,0V (after 10 seconds “ON”)

(*)4.5±1,0V (after heating)

3.2- Vary the frequency of CW oscillator between ±100KHz and verify if tension variation at the multimeter is higher than ±1,2V

AGC-RF ADJUSTMENTS

1- REQUIRED EQUIPMENT

1.1- Digital Multimeter

1.2- Attenuator

2- PREPARATION

2.1- Tune a COLORBAR patten.

2.2- Adjust the input signal level to 64±2dB ( 75Ω open). 2.3- Connect Digital multimeter between TPE23 and

ground

3- ADJUSTMENTS

3.1- Select DAC AGC RF(RF) CHQ4 (Service Mode) 3.2- Adjust the DAC using the keys VOL(+) and VOL(_)

until ±6,2V at TPE23.

NOISE LEVEL ADJUSTMENTS

1- REQUIRED EQUIPMENTS

1.1- Oscilloscope

1.2- 7KHz filter

Oscilloscope

2- PREPARATION

2.1- Tune a COLORBAR patten (no sound modulation). 2.2- Position tone control to center

2.3- Position VOLUME control to maximum.

2.4- Connect Oscilloscope to speakers terminals.

3- VERIFICATION

3.1- The maximum amplitude of the noise signal should be less than 1,5Vp-p.

3.2- When it is higher than 1,5Vp-p, activate 7KHz filter at the speakers terminals and verify if noise level is less than 0,5Vp-p.

1,5Vp-p

ENGLISH

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