DOWNLOAD Panasonic KX-MB1500UCW / KX-MB1520UCB Service Manual ↓ Size: 17.34 MB | Pages: 127 in PDF or view online for FREE

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KX-MB1500UCW/KX-MB1520UCB

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KX-MB1520UC:

 MAIN BO

ARD BLOCK DIA

GRAM

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KX-MB1500UCW/KX-MB1520UCB

NCU is the with the telephone line. It is composed of Bell detection circuit, Pulse dial circuit, Line amplifier and sidetone circuits. The
following is a brief explanation of each circuit.

1. Circuit Operation

Normally, this relay switches to the external telephone side and switches to the open side while OFF-HOOK.
IC300 (U25) High Level

→Q201 ON→RLY100 (ON)

1. Circuit Operation 

The signal waveform for each point is indicated below. The signal (low level section) input to L23 of SOC (IC300) on the digital
board.
TEL LINE 

→ PC103 (1, 2 → 4) → IC300 (L23)

The pulse dial is generated by operating the transistor Q203 and photo coupler PC104 while OFF-HOOK (RLY100 ON) condi-
tion.
Make state:
IC300 (U25) High Level 

→ Q202 ON → PC101 ON

IC300 (U25) High Level 

→ Q203 ON → PC104 ON

Break state:
IC300(U25) High Level 

→ Q202 ON → PC101 ON

IC300(U25) LOW Level 

→ Q203 OFF → PC104 OFF

1. Circuit Operation

The reception signal output from the line transformer T100 is input to pin (2) of IC201 via C256, R224 and then the signal is
amplified at pin (1) of IC201 and sent to the reception system at through the LPF.

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KX-MB1500UCW/KX-MB1520UCB

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.154).

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.32).

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KX-MB1500UCW/KX-MB1520UCB

The general speaker phone operation is performed by IC203 which has a speaker phone circuit. The alarm tone, the key tone,
and the beep are output from Soc IC300.

1. Function

This is the function when you are not holding the handset and can hear the caller’s voice from the line.

2. Circuit Operation

(Signal Path)
Signals received from the telephone line are output through at the speaker via the following path.

3. Signal Path

Refer to Check Sheet for Signal Route of Speaker RX (P.154).

1. Function

This circuit monitors various tones, such as (1) DTMF tone, (2) Alarm/Beep/Key tone/Bell.

2. Signal Path

a. DTMF MONITOR

(Speaker Operation)
Refer to Check Sheet for Signal Route of DTMF Monitor (Speaker) (P.154).

b. ALARM/BEEP/KEY TONE/BELL

Refer to Check Sheet for Signal Route of Ringing/Alarm/Beep/Key tone (P.154).

1. Function

When TAM is connected to this unit, the unit receives documents for FAX calls or the external TAM records a voice message
automatically.

2. Circuit Operation

The TAM INTERFACE circuit consists of Soc(IC300) to detect the other party CNG signal, and RLY100 to separate EXT.TAM.

a. CNG signal detection circuit

The CNG signal from the other party’s FAX is detected in Soc IC300 
(Signal path)
Refer to Check Sheet for Signal Route of CNG/DTMF detection (P.154).

b. Remote receiving

This is the parallel-connected DTMF signal for the TEL or EXT.TEL mode between T and R. When the other party is a
FAX, the unit switches to FAX receiving.
(Signal Path)
Refer to Check Sheet for Signal Route of DTMF detection (ON-Hook) (P.154).