Xerox WorkCentre 385, Service Manual

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LIU PBA
WorkCentre 385
12/98
7 - 43
Line Current Detector
• When CML1 relay connects telephone line,
U3 (STI9510) of LIU PBA and MFP controller
of the main PBA (U16) start communication
through UART. U3 of LIU PBA sends signal
that includes information of line current value,
whenever it receives orders or data from U16
of the main PBA.
Serial Interface
This part does serial communication with MFP
controller of the main PBA (MAIN PBA:U16) that
controls the whole system. It controls LIU by giving
and taking all control orders and line status.
• U3-11 RxD: Schmitt Trigger input, Receiving
terminal.
• U3-29 TxD: Open Drain output terminal.
• Standard UART communication.
- Baud Rate: 9600bps
- Start, Stop bit: 1bit each
- Data bits: 8 bit
- Parity bit: none
Major Functions Of Parts
1. U3: STI9510
- Key part of LIU PBA. Speech Network,
Dialer, Ringer and UART are built in one IC
package.
2. U5: PC817
- Photo coupler. It enables UART of
U3(STI9510) to receive control signal or
dialing information from MFP controller of the
main PBA (U15).
- Insulation Between primary and secondary
circuit part.
3. U6: PC817
- Photo coupler. It enables UART(U3-29:TxD)
of U3(STI9510) to deliver telephone line
status or response signal about control signal
or dialing information from LIU MFP controller
of the main PBA (U15).
- Insulation Between primary and secondary
circuit part.
4. U4: PC817
- It senses and delivers ring signal to the
main PBA.
- Insulation Between primary and secondary
circuit part.
5. U2: PC814
- It senses hook-off (Line connection) of the
external telephone and delivers it to the main
PBA.
- Insulation Between primary and secondary
circuit part.
6. BD1: BRIDGE DIODE
- Regardless of the polarity of DC power from
telephone line, the voltage put out on Pin.1
has polarity against pin Pin.2. So
DC loop forms always in the same direction
regardless of the polarity of the telephone
line.
7. T2,T3: TRANSFORMER
- It delivers signals from the telephone line to
modem or signals from modem to the
telephone line.
- Insulation Between primary and secondary
circuit part.
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