Panasonic KX-MB2230RU / KX-MB2270RU / KX-MB2510RU / KX-MB2540RU Service Manual ▷ View online
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KX-MB2230RU/ KX-MB2270RU/ KX-MB2510RU/ KX-MB2540RU
6.3.2.
RTC Backup Circuit
1. Function
This unit has a lithium battery (BAT300) which works for the Real Time Clock IC (RTC: inside IC300).
The RTC continues to work, backed up by a lithium battery even when the power switch is OFF.
*RTC:(Real Time Clock)
Chip for the clock mounted on the motherboard.
Receiving power supply to operate even while the power is off unlike the other chips on the motherboard.
The RTC continues to work, backed up by a lithium battery even when the power switch is OFF.
*RTC:(Real Time Clock)
Chip for the clock mounted on the motherboard.
Receiving power supply to operate even while the power is off unlike the other chips on the motherboard.
2. RTC Inside (IC300) Backup Circuit Operation
When the power switch is turned ON, power is supplied to the RTC (inside IC300). At this time, the voltage at pin AF7 of the
IC300 is +3.3V. When the power switch is turned OFF, the BAT300 supplies power to RTC through DA300.
When the power switch is OFF and the voltage of +3.3V decreases, pin AF7 of RTC (IC300) becomes roughly the same volt-
age as the battery voltage. RTC goes into the backup mode, in which the power consumption is lower.
IC300 is +3.3V. When the power switch is turned OFF, the BAT300 supplies power to RTC through DA300.
When the power switch is OFF and the voltage of +3.3V decreases, pin AF7 of RTC (IC300) becomes roughly the same volt-
age as the battery voltage. RTC goes into the backup mode, in which the power consumption is lower.
6.3.3.
Modem Circuit Operation ( Fax supported models only )
The modem (Included IC300) has all the hardware satisfying the CCITT standards mentioned previously.
ALL processing is controlled by the SOC (IC300) according to CCITT procedures.
This modem (Included IC300) has an automatic application equalizer. With training signal 1 or 2 at the time of G3 reception, it can
automatically establish the optimum equalizer.
ALL processing is controlled by the SOC (IC300) according to CCITT procedures.
This modem (Included IC300) has an automatic application equalizer. With training signal 1 or 2 at the time of G3 reception, it can
automatically establish the optimum equalizer.
Facsimile Transmission/DTMF Line Send
The digital image data sent on ATXD line from modem (Included IC300).
DAA IC100 (6
DAA IC100 (6
→9,10), Line side DAA IC101 and the NCU section to the telephone line.
Facsimile Reception
The analog image data which is received from the telephone line passes through the NCU section and enters line side DAA
(Direct Access Arrangement) IC100. The signals are changed to digital data in IC101 (5,6), IC100 (9,10
(Direct Access Arrangement) IC100. The signals are changed to digital data in IC101 (5,6), IC100 (9,10
→5) and IC300. In this
case, the image signals from the telephone line are transmitted serially. Here, the internal equalizer circuit reduces the image
signals to a long-distance receiving level. This is designed to correct the characteristics of the frequency band centered around
3kHz and maintain a constant receiving sensitivity.
signals to a long-distance receiving level. This is designed to correct the characteristics of the frequency band centered around
3kHz and maintain a constant receiving sensitivity.
Busy/Dial Tone Detection
The path is the same as Facsimile Reception.
Call Tone Transmission
This is the call signal which is generated the SOC (IC300) and sent to the speaker.
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KX-MB2230RU/ KX-MB2270RU/ KX-MB2510RU/ KX-MB2540RU
6.3.4.
TEL Line Section ( Fax supported models only )
Composed of ITS circuit and NCU circuit.
6.3.4.1.
Description of Block Diagram in Analog Section
Function
The analog section works as an interface between the telephone line.
DAA control ITS circuit and NCU circuit.
DAA control signals are output from SOC (IC300).
DAA control ITS circuit and NCU circuit.
DAA control signals are output from SOC (IC300).
Circuit Operation
[NCU]: Network Control Unit the NCU comprises of the following; DC loop forming circuit to connect with the telephone line;
Switching circuit for other interconnected telephones; Bell detection circuit; Remote fax activation circuit.
Refer to NCU Section ( Fax supported models only ) (P.36) for the details.
Switching circuit for other interconnected telephones; Bell detection circuit; Remote fax activation circuit.
Refer to NCU Section ( Fax supported models only ) (P.36) for the details.
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KX-MB2230RU/ KX-MB2270RU/ KX-MB2510RU/ KX-MB2540RU
6.3.4.2.
Block Diagram
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KX-MB2230RU/ KX-MB2270RU/ KX-MB2510RU/ KX-MB2540RU
6.4.
NCU Section
( Fax supported models only )
NCU: (Network Control Unit)
Requires for connecting computers to public communication networks and send a dial signal to call the other party.
Requires for connecting computers to public communication networks and send a dial signal to call the other party.
6.4.1.
General
NCU is the with the telephone line. It is composed of an EXT. TEL. line relay (RLY100), bell detection circuit, TAM interface circuit
and line amplifier. The following is a brief explanation of each circuit.
and line amplifier. The following is a brief explanation of each circuit.
6.4.2.
EXT. TEL. Line Relay (RLY100)
1. Circuit Operation
Normally, this relay switches to the external telephone side and switches to the open side while OFF-HOOK.
IC300 (P23) High Level
IC300 (P23) High Level
→Q105 ON→RLY100 (ON)
6.4.3.
Bell Detection Circuit
1. Circuit Operation
The signal waveform is indicated below. The bell signal input to IC101 and ring detected signal output from pin 15 of IC100.
IC300 monitor this signal and judged as bell.
TEL LINE
IC300 monitor this signal and judged as bell.
TEL LINE
→IC101 (8,9-5,6) → IC100 (9,10-15) → IC300 (AD17).
6.4.4.
Remote FAX Activation Circuit
1. Function
Another telephone connected to same line activates the unit to the FAX mode by using a DTMF signal.
2. Signal Path
Refer to Check Sheet for Signal Route of CNG/DTMF detection (P.214).
6.4.5.
TAM Interface Circuit
This circuit is to switch between FAX receiving and the external TAM’s message recording automatically.
For details, please refer to TAM Interface Section (P.37).
For details, please refer to TAM Interface Section (P.37).
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