Hitachi DV-P250U Manual De Servicio página 17

R1527
Filter 1
This 3-section filter constitutes a low pass filter of overall cutoff frequency of 44KHz. Audio signals after
low pass filter is amplified by IC1510 by about 6dB and output to audio out1 and audio out2.
Here, among audio signals, FL signals are input at pin 3 of IC1508 and output from pin 1, then input to pin
2 of IC1510 then output from pin 1.
FR signals are input at pin 5 of IC1508 and output from pin 7, then input to pin 6 of IC1510 then output
from pin 7.
3. MUTE CIRCUIT (DEC substrate, RJK substrate)
The principal role of mute circuit is the erasing of useless noises occurring when power is turned on.
Mute signal for noise erasing is generated by SH MICOM, reverse-amplified by Q1505 and Q1506. Then
by putting Q1310 and Q1311 'ON', it mutes audio signals.
In addition, if IC1502 detects no-signal, it generate a mute signal called ZERO MUTE. This latter is
reverse-amplified by Q1507 and mutes useless audio signals by putting Q1310 and Q1311 'ON'.
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C1561
2
R1529 R1531
3
C1559 C1563
Filter 2
R1533
1
C1567
IC1508
Filter 3
C1571
Chapter 1