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CIRCUIT DESCRIPTION
V Mute 1 FOR AUDIO MUTE
The V Mute 1 signal is also routed to the base of Q024 turning it ON. The high produced on its emitter is
now called V Mute 2 which is routed to two places. First, to the anode of DC04, to the base of QC03
which turn ON and grounds pin (11) of IC01 placing the Front Audio output IC into Mute. Second, to
PSU1 connector pin (14), which mutes the Center and Rear audio, output ICs. See the Surround Mute
ERRMUTE pin (18) of the Microprocessor
When the Microprocessor deems it necessary to mute the audio, it outputs a ERRMute signal from pin (18)
to I014 pin (7) the Level Shift IC. This IC outputs the high from pin (13) to three places. First, to the Audio
DSP circuit via the PSU2 connector pin (6) to mute the internal functions of the DSP. Second, to the
Surround PWB via the PSU1 connector, pin (7) called Mute. Here the audio outputs for out to Hi-Fi,
Transmitter out and Sub woofer are muted. Third. to the anode of DC01, then to the base of QC01 and
QC02 which grounds the audio input to pin (4 Right audio in and 2 Left audio in) of IC01.
F.Spk Off FRONT SPEAKER OFF
When the customer accesses the Main Menu and selects the Front Speaker Off selection, DAC IS01 on
the Surround PWB outputs a high from pin (6). This high is routed through the PSU1 connector pin (6) to
the anode of two diodes. First, to the anode of DC03, to the base of QC03 which turn ON and grounds
pin (11) of IC01 placing the Front Audio output IC into Mute. Second, to the anode of DC02, then to the
base of QC01 and QC02, which grounds the audio input to pin 4 Right audio in and 2 Left audio in) of
IC01.
AC LOSS DETECTION:
AC is monitored by the AC Loss detection circuit. The AC input from PQS1 pin (10) is rectified by DN09.
This charges up C009 and through DN08, it charges C008. When AC is first applied, C008 charges slightly
be-hind C009 preventing activation of Q001. If AC is lost, C009 discharges rapidly pulling the base of
Q001 low, however DN08 blocks C008 from discharging and the emitter of Q001 is held high. This action
turns on Q001 and produces a high. This high is routed through D029 to the base of Q022 turning it ON.
The collector goes low and pulls the base of Q023 low turning it ON. The emitter of Q023 is connected to
STBY +11V, so when it turns ON, its collector output goes HIGH. This high is now called V Mute 1. V
Mute 1 is routed to two circuits, see V Mute 1 explanation on the previous page.
SPOT:
SPOT is generated from the deflection PWB when either Horizontal or Vertical deflection is lost. This is to
pre-vent a horizontal or vertical line from being burnt into the CRTs. See Horizontal and Vertical Sweep
Loss Detection circuit and explanation for details. This high is input from PSD2 pin (6), through D027 to the
base of Q022 turning it ON. The collector goes low and pulls the base of Q023 low turning it ON. The
emitter of Q023 is connected to STBY +11V, so when it turns ON, its collector output goes HIGH. This
high is now called V Mute 1. V Mute 1 is routed to two circuits, see V Mute 1 explanation on the previous
page.
