Konica Minolta bizhub 200 Service Manual page 146

Theory of Operation Ver. 1.0 Aug. 2005
C. Image memory backup circuit (Si3056 silicone DAA)
• The silicone DAA (Direct Access Arrangement) processes almost all kinds of analog
communications for blocks following the modem DSP or blocks from the analog front-end
section (AFE) to the line.
Its main functions are as follows.
• Isolation function for line side first system line and the second system line (*1)
• A/D and D/A conversion function (CODEC)
• Analog hybrid (HYB) circuit
• Monitoring function for Tx/Rx analog circuit and line
• Direct current loop (DC termination) adjustment function (*2)
• 600 W termination alignment (AC termination) function
• Ringer signal detection (binary) function
• Dial pulse generation and output function
• Line direct current polarity monitoring function
*1: The function substitutes for the existing transformer and a photo coupler.
*2: Performs CML on/off (connection/release) and detects connected telephone off hook.
Therefore no relay operation sound occurs unlike before.
• This board consists of 2 tips (Si3056 and Si3019) and is positioned on the same memory
area with the modem DSP. All communication protocol signals, image signals, ringer
binary signals and tonal signals are superposed on a 2 MHz modulation signal unique for
the silicone DAA and transmitted.
• The Si3056 tip on the DSP side uses +3.3 V power supply in common with the modem
DSP. The Si3019 tip operates by the line superposition DC 48 V.
• Therefore, the board does not operate in the communication line without power supply
(Back to back). It always needs to be connected with such as the pseudo exchange in
the communication test.
• The board has two modular connection ports (for line connection and connected tele-
phone connection).
• When connecting the public line to the line connection modular port of the board, use the
attached 2-core cable.
• When operating the device with the 4-core cable connected, malfunction may occur.
3. Summary of Board functions
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