Philips EM7U LCOS, Service Manual

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AUDIO SIGNAL FLOW BLOCK (Figure 59)
The LCOS projector has a two-channel, 20 watt per channel, audio system. The Picture and
Audio source can be selected from any one of seven inputs. The AV inputs are located on
the Jack Panel, Scaler board, or Front Jack panel. The Audio processing for the Tuner is
located on the SSB. The Audio Amplifier is located on a board behind the System board.
AV3 and AV4 inputs are located on the Jack Panel board (1FH Cinch). AV5 and AV6 audio
inputs are located on the Scaler board. These inputs are fed to switch 7113 located on the
System board. The selected output from the System board is fed to the Jack panel and IC
7100. IC 7100 selects between the output of 7113, AV1, AV2, and the Front Jack panel. IC
7100 can select two outputs from any one of these inputs. The selected outputs are fed to
the SSB (Small Signal Board). The Audio Processor on the SSB outputs the audio in a digital
form via connector 1683 to an Audio Delay circuit located on the System board. Due to the
time required to process the video signal, it is necessary to delay the audio to ensure proper
sync. Left and Right audio is output to the Audio Amplifier via connectors 1205 and 1700.
Left and Right audio from the amplifier is output to the Center Speaker Switch before being
fed to the speakers.
Monitor audio is output from the Audio Processor on the SSB to the MON OUT jacks located
on the Jack Panel via the System board. Headphone audio from the SSB is output to a
switch, 7116, located on the System board. In addition, L-SC2_AV1-IN and R-SC2_AV2-IN
are also fed to the switch. IC 7116 is a combination switch and volume control. The output
of 7116 is fed to IC 7117, Headphone Amplifier, before being fed to the Front Jack panel. IC
7116 controls headphone volume.
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