Panasonic KX-NS500 / KX-NS520 Service Manual / Supplement ▷ View online
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2 Technical Descriptions
2.1.
Power Supply Unit
Changed from Original Service Manual as section 4.4.
This unit is switching regulator power supply and supplies DC voltages to CPU Board (MPR), and optional card (free slot).
PSU (power supply unit) has two outputs (41V, 15V). 15V output is supplied only in CPU Board (MPR) and option card.
Other outputs are mainly used as an object for the electric supply to a terminal.
PSU (power supply unit) has two outputs (41V, 15V). 15V output is supplied only in CPU Board (MPR) and option card.
Other outputs are mainly used as an object for the electric supply to a terminal.
2.1.1.
Block Diagram and Circuit Description of PSU
Changed from Original Service Manual as section 4.5.1.
2.2.
AC input, Rectification Smoothing Circuit
Changed from Original Service Manual as section 4.6.
1) Filter Circuit
This circuit consists of the following components and removes the exogenous noise or the noise generated at power supply.
CX1, CX2: normal mode filter (X-Capacitor)
LF1, LF2: common mode noise filter
CY1, CY2: common mode noise filter (Y-Capacitor)
CX1, CX2: normal mode filter (X-Capacitor)
LF1, LF2: common mode noise filter
CY1, CY2: common mode noise filter (Y-Capacitor)
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2) Rectification Smoothing Circuit
This circuit consists mainly of the following components and performs AC-DC conversion.
D2: Diode Bridge
C4: Primary Smoothing Capacitor
D2: Diode Bridge
C4: Primary Smoothing Capacitor
3) Surge Absorber Circuit
As the main component of this circuit, VR1 protects the system against exogenous noise such as lightning surge.
VR1: Varistor
VR1: Varistor
4) Inrush Current Avoiding Circuit
Immediately after AC input applies voltage, the following components control inrush current to the Smoothing Capacitor.
RT1: thermistor
RT1: thermistor
5) AC Detection Circuit
This circuit consists of the following components and detects AC input voltage.
Main components: D9, D10, D24, Q8, Q12, Q13, U1, Z7
AC voltage commutates through D9, D10.
When AC voltage is over the threshold, Q8, Q12, and Q13 are switched ON to allow AC Detection Circuit to transfer AC input
status to the secondary side AC alarm signal delivery section through U1.
Main components: D9, D10, D24, Q8, Q12, Q13, U1, Z7
AC voltage commutates through D9, D10.
When AC voltage is over the threshold, Q8, Q12, and Q13 are switched ON to allow AC Detection Circuit to transfer AC input
status to the secondary side AC alarm signal delivery section through U1.
2.3.
Main Converter
Changed from Original Service Manual as section 4.7.
This section describes the main converter circuit which insulates the primary DC voltage and converts the voltage to a Secondary
voltage “ Vout” (41V).
This section describes the main converter circuit which insulates the primary DC voltage and converts the voltage to a Secondary
voltage “ Vout” (41V).
1) Main Converter Section (Primary)
This main converter consists of the following components.
Q6: main switch FET
T1: isolation transformer
U2: Controls Q6
U4: device for transfer control secondary side
Other peripheral circuit
Q6: main switch FET
T1: isolation transformer
U2: Controls Q6
U4: device for transfer control secondary side
Other peripheral circuit
Secondary side output condition is transferred by U4 to the primary side.
Q6 is switched to ON/OFF in U2 to control the secondary side voltage.
Q6 is switched to ON/OFF in U2 to control the secondary side voltage.
2) Main converter section (Secondary)
T1: The output of this isolation transformer is 41V, and is the power supply for output voltage in section 3.
RT2: If the heatsink of Q6 become too hot.
RT2: If the heatsink of Q6 become too hot.
Vout:
This output consists of the Rectification Smoothing Circuit of D6, C10, C11, C36.
This is the source of 15V output and 41V output of PSU.
The thermistor RT2 decreases the resistance value.
This is the source of 15V output and 41V output of PSU.
The thermistor RT2 decreases the resistance value.
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3) Latch function for protection
Control IC U2 has the latch fonction to stop the PSU operation when over heat or over voltage is detected .
To release the latch status, release the abnormal state at first, then remove the AC cord from PSU and leave for 60 seconds
before restart.
To release the latch status, release the abnormal state at first, then remove the AC cord from PSU and leave for 60 seconds
before restart.
2.4.
DC Switch and DC Output Circuit
Changed from Original Service Manual as section 4.8.
This section describes the operation of the 41V output circuit and 15V output circuit which consists of DC/DC converter.
This section describes the operation of the 41V output circuit and 15V output circuit which consists of DC/DC converter.
1) DC Switch
Vout(41V), the output of Main Converter is supplied to post circuits via CN100 and DC Switch mounted on the cabinet.
2) 41V Output
2-1) 41V Overcurrent Protection Circuit
This circuit consists of mainly of Q19, R62, R105 and Q15
When Overcurrent flows to R62, the voltage potential defference between R62 and R105 is detected by Q19 and Q19 turns
ON.
Then Q15(FET Switch) turns OFF.
Consequently the fold back current limiting shuts down 41V output.
To control this circuit, +60V voltage which is generated in 15V Circuit.
When Overcurrent flows to R62, the voltage potential defference between R62 and R105 is detected by Q19 and Q19 turns
ON.
Then Q15(FET Switch) turns OFF.
Consequently the fold back current limiting shuts down 41V output.
To control this circuit, +60V voltage which is generated in 15V Circuit.
2-2) 41V Output Converter Circuit
41V is devided to two outputs, "+41V" and "+41V_OP")
"+41V" is fed to the circuit on Base Board / CPU Boaerd.
"+41V_OP" is fed to the optional card via Base Board.
"+41V" is fed to the circuit on Base Board / CPU Boaerd.
"+41V_OP" is fed to the optional card via Base Board.
3) 15V Output
3-1) 15V Output Converter Circuit
This circuit generates +15V from +41V.
This circuit consists of mainly of F4, C12, U7, D14, L3, C26
This circuit consists of mainly of F4, C12, U7, D14, L3, C26
3-2) 15V Output Overcurrent Detection Circuit
This circuit consists of mainly of R63, Q30, and Q31.
If overcurrent of 15V output is detected, Q30, Q31, and Q29 get ON, then SD(Shut Down) pin of U7 get high and U7 shut
downs.
If overcurrent of 15V output is detected, Q30, Q31, and Q29 get ON, then SD(Shut Down) pin of U7 get high and U7 shut
downs.
3-3) 15V Output Overvoltage Detection Circuit
This circuit consists of mainly of Z12, Q28 and Q27.
If overvoltage of 15V output is detected, Q28, Q27, and Q29 get ON, then SD(Shut Down) pin of U7 get high and U7 shut
downs.
If overvoltage of 15V output is detected, Q28, Q27, and Q29 get ON, then SD(Shut Down) pin of U7 get high and U7 shut
downs.
4) Overvoltage Detection Circuit-2
When 15V or 41V output becomes abnormally high, it makes Photo Coupler U3 ON via D13.
Then the control IC(U2) stops with the latch mode.
Then the control IC(U2) stops with the latch mode.
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2.5.
Battery voltage input and output
Changed from Original Service Manual as section 4.9.
This section describes the operation of battery input and output.
This section describes the operation of battery input and output.
1) Battery voltage output (charge time)
Charge circuit has constant voltage and constant current.
When the battery voltage is high, a controlled fixed voltage of the main converter is output.
When the battery voltage is low, a controlled fixed current of main converter is output.
When DC switch is turned on and CN102 (3)-(4) is short circuited, the main converter output supplies voltage with controlled
circuit, and Q7, Q11, Z4 change to ON. Q1, Q2 of DC switch circuit is turned on and battery output.
When the battery voltage is low, battery output is limited to a fixed current controlled by R1, R2, R3, and Q4.
When voltage is even lower.
When the battery voltage is high, a controlled fixed voltage of the main converter is output.
When the battery voltage is low, a controlled fixed current of main converter is output.
When DC switch is turned on and CN102 (3)-(4) is short circuited, the main converter output supplies voltage with controlled
circuit, and Q7, Q11, Z4 change to ON. Q1, Q2 of DC switch circuit is turned on and battery output.
When the battery voltage is low, battery output is limited to a fixed current controlled by R1, R2, R3, and Q4.
When voltage is even lower.
2) Battery voltage input (power outage)
When AC input falls, is shifts to the backup supply from the battery. Battery voltage conducts to FET Q2 and diode D1, and is
supplied by main converter output (C10, C11, C36).
When the battery voltage is reduced, Q7, Q11, Z4 on the battery control circuit go OFF. Q2 of the battery input/output DC switch
circuit goes to OFF status and releases the battery which stops the power supply.
supplied by main converter output (C10, C11, C36).
When the battery voltage is reduced, Q7, Q11, Z4 on the battery control circuit go OFF. Q2 of the battery input/output DC switch
circuit goes to OFF status and releases the battery which stops the power supply.
Battery Voltage
Input / Output Terminal
Input / Output Terminal
GND
(A) Battery Input / Output
DC Switch Circuit
(D1,Q1,Q2,Q4)
F2
CN102
3
4
(B) Battery Operation
Control Circuit
(Q7,Q11,Z4,R1,R2,R3)
Control Circuit
(Q7,Q11,Z4,R1,R2,R3)
Main Converter
Output
Output
41V
,BATT
Voltage for Drive
3
4
9
Secondary
GND
GND
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