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DP-4X AUDIO VIDEO MUTE CIRCUIT EXPLANATION
V MUTE: From Pin 49 of the Microprocessor I004
When its necessary to mute the audio as described on the first page, the Microprocessor outputs a High from pin
49. This high is routed to the Level Shift IC I009 pin 9 as 3.3V. This voltage is level shifted to 5V by this IC and
output as V MUTE 1 from pin 11. This high is routed to the following 3 circuits;
V MUTE 1 HIGH ACTIVATES THE FOLLOWING 3 CIRCUITS:
1.
Front Audio Out Hard signal mute: The high from pin 11 of I009 (V Mute 1) is routed to DA04. The
high continues to the base of QA10. When this transistor turns on, it supplies a Lo to pin 11 of IA02 and
hard mutes the Audio Out. (Note: This is not the same thing as the Mute selected from the customer's
remote. This is controlled by the Front Audio Control IC IA01 internally and functions in three states,
No Mute = 100%, 1/2 Mute = 50% and Full Mute = 0%.
2.
Front Audio Input Signal Mute. The high from pin 11 of I009 (V Mute 1) is routed to DA03. The high
continues to the bases of QA07 and QA08. When these transistors turn on the ground the Audio Front
Right and Left signal input to the Audio Output IC IA02 and pins 4 and 2.
3.
Out to Hi-Fi Mute Path: The high from the Level shifter I007 pin 13 is routed to the anode of DA53
and then to the cathodes of DA51 and DA52 to the base of QA51, and QA54. When these transistor
turns on, they ground the audio going into the audio for Out to Hi-Fi audio output jacks.
AUDIO MUTE PATH: From Pin 71 of the Microprocessor I004
The Microprocessor outputs a High from pin 71. This high is routed to the Level Shift IC I009 pin 8 as 3.3V. This
voltage is level shifted to 5V by this IC and output as A MUTE from pin 12.
Audio Mute: This high from pin 12 of I009 is routed to the following 3 circuits;
1.
Front Audio Out Hard signal mute: The high from pin 12 of I009 (Audio Mute) is routed to DA14.
The high continues to the base of QA10. When this transistor turns on, it supplies a Lo to pin 11 of
IA02 and hard mutes the Audio Out. (Note: This is not the same thing as the Mute selected from the
customer's remote. This is controlled by the Front Audio Control IC IA01 internally and functions in
three states, No Mute = 100%, 1/2 Mute = 50% and Full Mute = 0%.
2.
Main Tuner U301 Mute: The high from the Level shifter I009 pin 12 is routed to pin 19 of the PTU2
connector. Then to pin 25 of the Main Tuner U301. This high mutes the Audio and Video outputs from
the Tuner.
Front Audio Input Signal Mute. The high from pin 12 of I009 (Audio Mute) is routed to DA01. The
3.
high continues to the bases of QA07 and QA08. When these transistors turn on the ground the Audio
Front Right and Left signal input to the Audio Output IC IA02 and pins 4 and 2.
FRONT SPEAKER OFF: From Pin 17 of IA01
Front Speaker Off signal. The high from the Audio Control IC IA01 pin 17 goes to 2 circuits:
1.
Front Audio Out Hard signal mute: The high from pin 17 of IA01 (Spk Mute) is routed to DA14. The
high continues to the base of QA10. When this transistor turns on, it supplies a Lo to pin 11 of IA02 and
hard mutes the Audio Out. (Note: This is not the same thing as the Mute selected from the customer's
remote. This is controlled by the Front Audio Control IC IA01 internally and functions in three states,
No Mute = 100%, 1/2 Mute = 50% and Full Mute = 0%.
2.
Front Audio Input Signal Mute. The high from pin 17 of IA01 (Spk Mute) is routed to DA01. The
high continues to the bases of QA07 and QA08. When these transistors turn on the ground the Audio
Front Right and Left signal input to the Audio Output IC IA02 and pins 4 and 2.
PAGE 02-08
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