Zenith IQC50H94, Technical Training Manual

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CIRCUIT DESCRIPTION
ON THE SURROUND PWB:
Surround Board DAC3 IS01
This Digital to Analog converter acts as an extension of the Microprocessor. Sometimes called an Expansion
IC. The purpose of this IC is to reduce the number of pins, (fan out) of the Main Microprocessor I001. The
Main Microprocessor sends Clock and Data via I 2 C bus to the DAC3 IC. The output from the Micro-
processor is pins (59 SDA2 and 60 SCL2) then through the connector PSU1 pins (2 and 1) which arrives
at the DAC3 IC at pins (14 and 15) respectively.
The following is a list of the input and output pins on DAC3.
PIN FUNCTION
1. SW Sel 1 Turns on/off QS01 which either adds or doesn’t add Sub Woofer to Front L and
Front R for 3 way audio set up.
2. DSP CSI Digital Surround Module signal. If the Coax Audio input is noisy, the DSP tells
DAC3 to 2X invert the signal.
3. Opti/Coax Sel Controls IS17. Determines if the signal is 2X inverted due to noise.
4. RSPOFF Turns off the Rear Speaker outputs. Controlled by the customer’s menu.
5. CSPOFF Turns off the Center Speaker outputs. Controlled by the customer’s menu.
6. FSPOFF Turns off the internal Front Speaker outputs. Controlled by the customer’s menu.
7. SWSEL 2 Controls QS25 to add Front Left and Right to Sub Woofer.
8. Gnd Ground
9. P. Vol. Perfect Volume On/Off controlled by the customer’s menu. Note, when in Pro-
Logic mode, Perfect Volume is Off.
10. DSPREQ DSP Request Input.
11. SAD0 Ground Not Used
12. SAD1 Ground Not Used
13. SAD2 Ground Not Used
14. SDA2 Data I 2 C communications between DAC3 and Microprocessor
15. SCL2 Clock I 2 C communications between DAC3 and Microprocessor
16. Vcc IC B+. (STBY +5V)
Front Audio Control IS03
The Front Audio Control IC has the ability to adjust balance, treble, bass, volume and mute. This mute is
the one that is activated when the mute button is pressed on the remote control. Communication from the
Microprocessor via pins (59 SDA2 and 60 SCL2) then through the connector PSU1 pins (2 and 1) which
arrives at the IS03 at pins (4 and 5) respectively.
Center/LFE/PinP Audio Control IS08
This IC has the ability to adjust balance, treble, bass, volume and mute for the Center channel. This mute is
the one that is activated when the mute button is pressed on the remote control. It also adjusts the volume
for the PinP audio sent to the transmitter outputs as well as the volume for the Sub Woofer called LFE (Low
Frequency Effects). Communication from the Microprocessor via pins (59 SDA2 and 60 SCL2) then
through the connector PSU1 pins (2 and 1) which arrives at the IS08 at pins (4 and 5) respectively.