Panasonic KX-NT136RU Service Manual ▷ View online
8.8. LED CIRCUIT
The lighting of the LED is controlled by IC13.
The LED lights up in a dynamic lighting system.
The duty ratio is 1/8 (ON time 1.5ms).
The LED lights up in a dynamic lighting system.
The duty ratio is 1/8 (ON time 1.5ms).
The following LEDs light up in a static lighting system.
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•
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• D125 : AUTOANSER
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•
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• D126 : FORWARD/DND
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• D127 : CONF
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• D128 : AUTODIAL
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• D129 : INTERCOM
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KX-NT136RU
8.9. POWER SUPPLY CIRCUIT
This Power Supply Circuit supports the power supply through an Ethernet line called PoE (Power over Ethernet) as well as the
input from a regular AC adapter. It converts the power supply from the both to 3.8V and is supplied to a 3.3V and 1.8V regulator
on the MAIN board.
The power supply board consists of the four sections below.
input from a regular AC adapter. It converts the power supply from the both to 3.8V and is supplied to a 3.3V and 1.8V regulator
on the MAIN board.
The power supply board consists of the four sections below.
1. 802.3af Authentication Circuit
When the hub or router supporting 802.3af is connected to LAN port (JK3), the authentication voltage and the classification
voltage are supplied through the MAIN board between Pin 1, 2 and 5,6 or Pin 3, 4 and 7,8 of CN302.
When this voltage is detected automatically by IC302, it applies the corresponding current and is identified on the hub side, so
that the hub starts to supply 48V.
In that case, as there is OR with the power from LAN port (JK3) and the power from DC jack(JK301) by D303 and D302, the
power from LAN port is supplied to the switching regulator (IC301) preferentially.
voltage are supplied through the MAIN board between Pin 1, 2 and 5,6 or Pin 3, 4 and 7,8 of CN302.
When this voltage is detected automatically by IC302, it applies the corresponding current and is identified on the hub side, so
that the hub starts to supply 48V.
In that case, as there is OR with the power from LAN port (JK3) and the power from DC jack(JK301) by D303 and D302, the
power from LAN port is supplied to the switching regulator (IC301) preferentially.
2. Switching Regulator Circuit
This switches the power from the DC jack or LAN port with 200KHz by IC301 to generate 3.8V. The switching frequency is
200KHz.
200KHz.
3. Backup Power Supply Circuit
C301 is a super capacitor and performs backup during a temporary blackout.
Usually, the power is stored from DC jack (JK301) through D305 or from LAN port(CN302 pin 1, 2) through D306 to C301. It
is generally 8.2V and clipped by the Zener diode of D308.
Usually, the power is stored from DC jack (JK301) through D305 or from LAN port(CN302 pin 1, 2) through D306 to C301. It
is generally 8.2V and clipped by the Zener diode of D308.
4. Voltage Detection Circuit
The voltage supplied to the Switching Regulator Circuit goes under 6V, pin1 of IC303 then goes GND and informs the MAIN-
CPU and the SUB-CPU of the decreased voltage.
CPU and the SUB-CPU of the decreased voltage.
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KX-NT136RU
9 TROUBLESHOOTING GUIDE
9.1. NO OPERATION
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* Note:
Refer to waveform (1), (2) in 17.7. WAVEFORM (P.63).
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