Sony MDR-RF845RK Manual de servicio - Página 5

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Notes:

1. Use transmitter with check and adjustment already completed.

2. On adjusting the headphones section, use the transmitter as a

jig.

Headphones:MDR-RF845R

Transmitter:TMR-RF845R

Procedure:

1. Connect an oscillator with attenuator and terminator (600 Ω)

to the transmitter AUDIO IN-A connector (J402).

2. Connect an AC adapter to the transmitter DC IN 9V jack (J404).

3. Short between Q303 corrector and GND on the RX board.

4. Connect a DC 2.4V to the +B power line externally.

5. Connect lead wires to IC301 pin 4, pin 6, pin 7 and GND on

the RX-BASE board.

6. Connect a resistor 33k Ω between IC301 pin 4 and pin 7.

7. Connect lead wires to the speakers' terminals (L+,L-,R+,R-)

on the RX-BASE board.

3-1. Free Run Frequency Check and Adjustment

1. Set the transmitter AUDIO IN-A connector (J402) to no signal.

Note: In this case, operation time is about 5 or 10 minutes.

Perform confirmation for less than 5 minutes.

2. Check the transmitter power indicator (red) lights.

3. Set the transmitter CHANNEL switch to 1.

4. Connect DC 1.2V across TP and GND.

5. Connect a frequency counter to IC301 pin 4 and GND on the

RX-BASE board, then confirm the frequency within 76kHz

± 50Hz

6. When the frequency dose not satisfy the specified value, adjust

the value of the frequency counter to specification by RV301

on the RX-BASE board.

Specified values: 76kHz ± 50Hz.

7. Remove the 33 kΩ resister between IC301 pin 4 and pin 7.

Setting :

Regulated power supply

(DC 1.2V)

–

3-2. Receive Frequency Check and Adjustment

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-

A(L-ch) connector only.

4. Keep distance between transmitter and headphones to 5 meters

over.

5. Set the headphones volume (RV302) to minimum.

6. Connect DC1.2V across TP and GND.

7. Connect an oscilloscope CH1 and CH2 to IC301 pin 6 and

pin 4.

8. Check the waveform of the oscilloscope to CH1 is demodulated

1kHz signal and CH2 is GND.

9. If CH1 and CH2 are not satisfied in step 8, adjust the coil (L301)

on the RX board to satisfied step 8.

10. Open between Q303 corrector and GND on the RX board.

11. When the transmitter off, check the waveform of the oscilloscope

as follows:

1.8V

2-3sec

GND

ELECTRICAL ADJUSTMENTS

Frequency counter

IC301 pin4

GND

–

0.6V

SECTION 3

12. Set the transmitter CHANNEL switch to 1.

13. Push the headphones tuning switch (S301) to receive radio

frequency.

14. Check same step 8.

15. Set the transmitter CHANNEL switch to 3.

16. Push the headphones tuning switch (S301) to receive radio

frequency.

17. Check same step 8.

Setting :

Regulated power supply

(DC 1.2V)

–

3-3. Carrier Modulation Check

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A

(L-ch) connector only.

4. Set the headphones volume (RV302) to minimum.

5. Connect an oscilloscope CH1 and CH2 to IC301 pin 6 and

pin 4.

6. Push the headphone tuning switch (S301) to receive radio

frequency.

7. Check the waveform of the oscilloscope that the CH1 is

demodulated 1kHz signal and CH2 is GND.

8. Connect an AC voltmeter with LPF to IC301 pin 6 and GND.

9. Check the value of the AC voltmeter to 26mVrms ± 2mV

Setting :

Digital voltmeter

(AC range)

–

3-4. Separation Check

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A

(L-ch) connector only.

4. Connect an oscilloscope CH1 to speakers terminal (L+,L-) and

CH2 to IC301 pin 4 and GND.

5. Push the headphones tuning switch (S301) to receive radio

frequency.

6. Check the waveform of the oscilloscope that the CH1 is

demodulated 1kHz signal and CH2 is GND.

7. Connect an AC voltmeter with LPF to speakers terminal

(L+,L-).

8. Adjust the value of the AC voltmeter to specification by

headphones volume RV302.

Specified values: 155mVrms

9. Connect an AC voltmeter with LPF to speakersterminal

(R+,R-).

10. Measure the value of the AC voltmeter.

11. Check the difference of the L and R to more than 20dB.

12. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A

(R-ch) connector only.

13. Connect an AC voltmeter with LPF to speakers terminal

(R+,R-).

14. Adjust the value of the AC voltmeter to specification by

headphones volume RV302.

Specified values: 155mVrms

15. Connect an AC voltmeter with LPF to speakers terminal

(L+,L-).

16. Measure the value of the AC voltmeter.

— 5 —

Ver 1.2 2001. 11

OSCILLOSCPE

CH1

CH2

IC301 pin6

–

OSCILLOSCPE

LPF

2.2K

IC301

IC301 pin6

33000P

pin6

IC301 pin4

CH1

CH2

IC301 pin4

–