Samsung FACSIMILE SF40 Service Manual page 36

The handset contains a microphone and a conventional dynamic speaker.
Receiving signal is received through R16, R17, R18 and transmitting signal from handset mic. is amplified speech IC U2
pin 8 and through C36, R33 and amplified in the U2 inside Pin 1 and then transmitted to the tel. line through speech drive
TRQ1.
Dialing parts (U1, Q2, Q3, Q4) is operated in NO POWER state. In the TONE dial mode , U1 produce tone dial signal.
This signal is passed through LPF (Q4, R35,R36,R37,C33, C44) C34, R36 and is input U2 Pin 10 and transmitted same as
transmission path.
In the pulse mode , this sequence is passed to the line by dial switch Q3, Q1.
This section is composed of a ringer IC U3,U4 , and their peripheral components.
The ringer signal is supplied through C29 R39 to U3, where the signal is turned in to an FSK sound to drive the electrical
buzzer and also detect calling signal by R42, U4 in the calling signal. Sound volume selection among high, low.
OFF is made aw 1.
Signal / Data Interface Section
This section composed of relay K1, matching transformer T1, and performs dc loop line is get the facsimile side also per-
forms impedance matching in transmission/ reception of Tx/Rx signal in the facsimile machine and separation of the line
and secondary circuit.
Hook detection section
This is composed of a photo coupler U7 and their peripheral components. The section operates on DC loop interruption in
the exit phone line.
10-1-3. Fundamental Operational Description
1. Transmit Operation
In standby mode. Integrated facsimile controller checks out document detect sensor to see its status. If it goes on.
Stepping motor starts counter revolving to move CAM to Tx position. Afterwards, stepping motor revolves so that docu-
ment get loaded to CIS scanning point.
When START/COPY key is pressed in off-hook state, CML relay is connected to modem.
After the connection with the other party is completed, stepping motor moves document to the scanning point of CIS.
The opto-electrical converted image data in CIS is separated into Black and White by means of comparator, and stored in
shift register, consequently residing in External RAM after serial-to-parallel conversion.
These parallel data is compressed based on MH coding, and sent to modem.
Subsequently, the modem converts the digital data to analog form and transmits them to line through line interface unit.
2. Recieve Operation
Receive mode is categorized into manual reception, auto reception, and TEL/FAX switching.
In manual reception, CML relay is connected to modem after START/COPY key operation in off-hook state.
In automatic reception, IFC checks ring detect port to see if it changed from hi to low. If it does, CML relay is connected
automatically after pre-determinal ring count.
In TEL/FAX switching mode. TAD connected to external phone is involved.
in this mode, ring count is set to 6 times, and CML relay gets connected to modem after this 7 high to low transitions of
ring detect port.
The above reception modes are selected by RCV mode button.
IFC checks ring detect port, and makes stepping motor counter-revolve to position CAM to Rx mode.
Then, the data received from the other party is demodulated into digital form to be stored in external RAM.
The data stored in COMM. Buffer is decompressed on MH decoding scheme, and sent to TPH to print out the image.
3. Copy Mode
IFC checks document detect sensor in standby mode.
If the sensor turns on, stepping motor counter-turns to set CAM position to copy mode by the way Tx mode.
After copy mode is set, stepping motor turns in ordinary way and loads document to scanning point.
If START/COPY key is pressed in on-hook state. stepping motor turns to take down document.
The opto-electrical converted image data is divided into black and white.
Employing comparator, to be stored in shift buffer inside IFC-P.
This serial data is changed to parallel data to arrive at external RAM.
Then, the image data in external RAM is fed to TPH to print out the image.
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10-2. Circuit Diagram
10-2-1. Main
10-2-2. LIU
10-2-3. OPE
10-2-4. Daughter
10-2-5. Hook
10-2-6. D-DET
10-2-7. P-Empty
10-2-8. Power Supply
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