Sony FDL-PT22/JE service manual Section Circuit Adjustment, Board Adjustment

SECTION 3

CIRCUIT ADJUSTMENT

3-1. A BOARD ADJUSTMENT 3-2. T BOARD ADJUSTMENT

+4.5V ADJUSTMENT

- T BOARD - (COMPONENT SIDE)

Measure the voltage between JL32 (4.5V) and JL33 (GND) with a digital voltmeter, and adjust RV601 so that the voltage will be as follows:

<Specification>

4.45± 0.05VDC S601: UHF position

CONFIRMATION OF +30V

Measure the voltage between JL29 (30V) and JL33 (GND) with a digital voltmeter, and adjust RV601 so that the voltage will be as follows:

<Specification> 30.5 ± 1.5VDC

CONFIRMATION OF AUDIO OUTPUT

(1)Input 1kHz voice, 100% modulation from sound generator.

(2)Make RV501 MAX.

(3)Connect the probes of an oscilloscope to JL23 (SP) and JL15 (SP GND).

(4)Check the waveform on the oscilloscope, and make sure that it is within the standard.

<Specification> 1.5 - 2.8Vp-p

RV004

RV001

RV002

RV201

TU101

ROUGH ADJUSTMENT OF VIF.AFT

(1)Preparation

Set S601 in the VHF position.

Make JL18 (RF) signal-less

Insert 1kΩ between JL77 (4.5V) and JL28 (RF AGC).

Input a sweep signal to the section between JL26 (IF) and JL27 (IF GND).

		Sweep signal			0.01∝F
				ATT		JL26
fo		45.75MHz }5kHz 75 ¶ 6dB
			Fig.3-1
Note:	The sweep signal level should be -30 ± 5dBm at JL26.
	The distance between the ATT output and JL26
	should be as short as possible.

(2)Insert the output between JL72 (VIDEO) and JL71 (A.GND) to an oscilloscope, and apply external voltage (MGC) to JL51 so that the waveform shown in Fig.3-2 will appear (the mini- mum section should not clip). Adjust T202 so that the position of 45.75MHz will be the lowest.

Note: This portion should be approx. 1.0Vp-p when exter- nal voltage is applied to JL51 (MGC).

The external voltage applied to JL51 (MGC) should not exceed 4.3VDC.

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