SLV-F900, SLV-F990 - Sony VCR Service Manual (repair manual). Page 4

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The operation using the small antenna is described in the parenthesis (  ) below.

• The differential amplifier that consists of Q901 and Q902 (Q911 and Q913), drives the antenna.
• The modulated 13.56 MHz carriers having the opposite polarities each other, are supplied from IC901 pin@£ and pin@¶ (pin@ª and pin#¡)

respectively.

• Q901 (Q911) provides the output signal that swings in the range of 4 V to 20 V at the Q901 (Q911) collector due to L900 (L902).
• Q902 (Q913) provides the output signal that swings in the range of 4 V to 20 V at the Q902 (Q913) collector due to L901 (L903).

• Connect CH-1 of an oscilloscope to CN900 pin3 and CH-2 to CN900 pin2.
• Set CH-2 of an oscilloscope to INV.
• Set MODE of an oscilloscope to ADD.

pin

@£

 (pin

#¡

)

pin

@¶

 (pin

@ª

)

Fig. 2-1

• Amplitude of the output signal is doubled by the differential amplifier so that the output signal having amplitude of 42 V drives the antenna

because the carrier signals having the opposite polarities are supplied to Q901 (Q911) and Q902 (Q913) respectively.

20V

4V

0

Fig. 2-2

Fig. 2-3

32V