Panasonic KX-TEB308UA / KX-TE82460X / KX-TE82493X / KX-A227X Service Manual ▷ View online
10 EXPLANATION OF BLOCK DIAGRAM
10.1. MAIN UNIT (KX-TEB308UA)
10.1.1. Power Supply Circuit
This power supply unit is a switching power supply. Power supply unit supplies DC voltage (+27V,+15V,3.3V) to main board and
other optional cards. And this unit has an adaptor circuit to back up battery.
other optional cards. And this unit has an adaptor circuit to back up battery.
10.1.2. COL Interface Circuit
There are the interface circuits linking the CO line (CO1 -CO3) and the cross point circuit section.
10.1.3. Cross Point Circuit
This is a space division switching system for connecting the following:
The eight extension circuits with the three CO, DTMF generator, DTMF receiver, INT-CALL ID, MODEM, OGM, BV, paging, music
on hold, tone etc.
It is composed of 3 C-MOS IC´s. (8 X 16 matrix: 1pcs and 4 X 8 matrix: 2pce).
The eight extension circuits with the three CO, DTMF generator, DTMF receiver, INT-CALL ID, MODEM, OGM, BV, paging, music
on hold, tone etc.
It is composed of 3 C-MOS IC´s. (8 X 16 matrix: 1pcs and 4 X 8 matrix: 2pce).
10.1.4. Intercom Circuit
This is the interface circuit of the single line telephone, and it is composed of 8 intercom circuit (ICM1-8).
10.1.5. Power Failure Through Call Switching Circuit
There is one power failure transfer circuit (CO1-EXT101).
10.1.6. Data Communication Circuit
The APT i/f module which performs communication with a private telephone machine is built in ASIC.
10.1.7. Control Circuit
A control block consists of CPU (compatibility with Intel 8086) (IC700), Flash ROM (8Mbit) (IC705) and SRAM (4Mbit) (IC704).
RTC, Timer, DMAC, USB Controller, WDT, INTC, UART, General Purpose I/O ports, APT i/f and DSP are built into CPU chip.
General purpose I/O block is composed by discrete parts (IC7, IC8) and the I/P port in CPU.
IC7 and IC8 control extension, and the I/O ports in CPU control the COL chiefly.
In order to maintain time, system data and others, RTC (Real Time Clock) in CPU and SRAM are backed up with the lithium battery.
RTC, Timer, DMAC, USB Controller, WDT, INTC, UART, General Purpose I/O ports, APT i/f and DSP are built into CPU chip.
General purpose I/O block is composed by discrete parts (IC7, IC8) and the I/P port in CPU.
IC7 and IC8 control extension, and the I/O ports in CPU control the COL chiefly.
In order to maintain time, system data and others, RTC (Real Time Clock) in CPU and SRAM are backed up with the lithium battery.
10.1.8. Tone Generator Circuit
The rectangle wave generated by the timer of CPU is changed into sine wave with a low pass filter, and various tones are
generated.
generated.
10.1.9. DTMF Generator Circuit
DTMF (Dial Tone Multi Frequency) generator is used for dispatch to outside line, and communication with the voice mail connected
to the extension.
to the extension.
10.1.10. DTMF Receiver Circuit
The circuit that receives the Dial Tone Multi Frequency by which extension dispatch is carried out with the DTMF receiver
connected to the crossing point.
connected to the crossing point.
10.1.11. Int Call ID Circuit
FSK/DTMF generated by DSP in CPU are connected even to a crossing point through AMP. The circuit which sends out a CALLID
signal to the telephone connected to an extension by connecting the line of INT-CALL-ID with arbitrary extensions.
signal to the telephone connected to an extension by connecting the line of INT-CALL-ID with arbitrary extensions.
10.1.12. Modem Circuit
The MODEM signal generated by DSP in CPU is connected even to a crossing point through AMP.
The circuit, which connects the line of MODEM with arbitrary outside line, and enables MODEM communication with outside line.
The circuit, which connects the line of MODEM with arbitrary outside line, and enables MODEM communication with outside line.
10.1.13. USB Circuit
The circuit which makes communication possible by PC and 1.1 standards by the USB controller in CPU.
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KX-TEB308UA
10.1.14. OGM Circuit
The 4M Serial Flash ROM is connected to CPU by the memory controller in DSP (in CPU).
A maximum of 3-minute storing of OGM is possible to a serial flash ROM.
A maximum of 3-minute storing of OGM is possible to a serial flash ROM.
10.1.15. Ring Signal Generator Circuit
This section generates the ring signal for the single line telephone. A 20/25Hz square wave is generated by the CPU timer and sent
to low pass filter and the Ring signal is amplified by BELL amplifier circuit, and then passed it through the ringing signal switching
relay to the single line telephone.
to low pass filter and the Ring signal is amplified by BELL amplifier circuit, and then passed it through the ringing signal switching
relay to the single line telephone.
10.1.16. SMDR Interface Circuit
This is the RS232C interface port. When the port is connected to a printer. The port can be used to output the SMDR feature
recording messages and the contents of the system program.
recording messages and the contents of the system program.
10.1.17. Door Phone Interface
An doorphone card interface consists of two intercom paths connected to a crossing point, and address data and CS signals.
10.1.18. Call ID Interface
A CALLID card interface consists of three CALLID signal lines from outside line, and address data and CS signal.
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KX-TEB308UA
11 CIRCUIT OPERATION
11.1. POWER SUPPY CIRCUIT
11.1.1. The function of the power unit are listed below
AC-DC Inverter Function
This function isolates and converts the AC input voltage to DC
input and output of DC27V.
input and output of DC27V.
DC-DC Converter Function
This function outputs DC+15V and 3.3V from the inputted
DC27V.
DC27V.
Battery Back Up Adaptor Function
This function connects battery and service unit without battery
adaptor, only needs a cable connected to the battery and
service unit.
adaptor, only needs a cable connected to the battery and
service unit.
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KX-TEB308UA
11.1.2. Control Section
1) AC-DC Inverter Function
The AC input voltage is rectified and smoothed by D10-13 and C5. The obtained DC voltage is converted into a rectangular wave
by the switching transistor Q1, then isolated and transduced by T1. This converted rectangular wave is rectified and smoothed by
D101 and C101 to output DC27V. The DC27V is transmitted to the primary side by PC1 and then PWM- controlled to keep
constant. The switching frequency of Q1 is approximately 60KHz.
2) DC-DC Inverter Function
The DC 27V DC is converted into a rectangular wave by control IC201, and then output as an output voltage of +15V by the
smoothing circuit which is composed of D201, L201, C201.
The 27V DC is converted into rectangular wave by control IC301 and then output as an output voltage of +3.3V by the smoothing
circuit which is composed of D301, L301, C301.
3) Battery back up function
This back up battery adaptor circuit has DC supply function, from battery (+24V) to service unit and DC charge from service unit
to battery (+24V). Charge current is typ. 0.3A.
The AC input voltage is rectified and smoothed by D10-13 and C5. The obtained DC voltage is converted into a rectangular wave
by the switching transistor Q1, then isolated and transduced by T1. This converted rectangular wave is rectified and smoothed by
D101 and C101 to output DC27V. The DC27V is transmitted to the primary side by PC1 and then PWM- controlled to keep
constant. The switching frequency of Q1 is approximately 60KHz.
2) DC-DC Inverter Function
The DC 27V DC is converted into a rectangular wave by control IC201, and then output as an output voltage of +15V by the
smoothing circuit which is composed of D201, L201, C201.
The 27V DC is converted into rectangular wave by control IC301 and then output as an output voltage of +3.3V by the smoothing
circuit which is composed of D301, L301, C301.
3) Battery back up function
This back up battery adaptor circuit has DC supply function, from battery (+24V) to service unit and DC charge from service unit
to battery (+24V). Charge current is typ. 0.3A.
11.2. CO INTERFACE CIRCUIT
11.2.1. Composition
This is composed of the following circuit:
1) Bell signal detection
2) DC loop formation circuit
3) Pulse dial transmission circuit
4) CALL ID interface circuit
5) COL bidirectional amplifier circuit
2) DC loop formation circuit
3) Pulse dial transmission circuit
4) CALL ID interface circuit
5) COL bidirectional amplifier circuit
1) Bell signal detection
When CO line is idle, photo coupler PC1, PC2 are OFF.
When there is an incoming signal from CO line, the current flows PC1 as in the following way.
Tip
When there is an incoming signal from CO line, the current flows PC1 as in the following way.
Tip
→ L1 → R2 → PC1(1-2) → C3 → R5 → L1 → Ring: This cause pin4 of PC1 to change the level from High to low.
Ring
→ L1 → R5 → C3 → PC2(1-2) → R2 → L1 → Tip: This cause pin4 of PC2 to change the level from High to low.
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