Panasonic KX-NCP500RU Service Manual ▷ View online
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KX-NCP500RU
4.6.2.
Main Converter
Provides a description of the main converter that insulates primary DC voltage and converts it to secondary (32V output, 41V
output and 41V SW output).
output and 41V SW output).
1. Main converter section (primary side)
Consisting of the following parts, the primary side main converter is an insulated, separately-excited flyback converter.
Q1: Main switch FET
T1: Insulated transformer
IC1: Control IC for Q1 control
PC1: Secondary control transmission element
Other peripheral circuitry
Secondary output status is transmitted from PC1 to the primary side; on/off control is executed by IC1 to control secondary
voltage.
Q1: Main switch FET
T1: Insulated transformer
IC1: Control IC for Q1 control
PC1: Secondary control transmission element
Other peripheral circuitry
Secondary output status is transmitted from PC1 to the primary side; on/off control is executed by IC1 to control secondary
voltage.
2. Main converter section (secondary side)
The T1 insulated transformer output consists of the following three outputs, and is the source of power for the output voltage
section described in Part 3.
32V output section:
Primary control output consisting of D201 and C201 - C204 rectifier smoothing circuits.
Serves as the source of power for 15V and 15 VPT output described in Part 3.
Controls output voltage by IC201 and R203 - R205 and transmits control status to primary side by PC1.
41V output section:
Output consisting of D101 and C101 rectifier smoothing circuits.
Serves as the source of power for 41V output described in Part 3.
41V switch output:
Consisting of D601 and C601 rectifier smoothing circuits, 41V switch output serves as source of power for FET Q151 for 41V
output control described in Part 3.
section described in Part 3.
32V output section:
Primary control output consisting of D201 and C201 - C204 rectifier smoothing circuits.
Serves as the source of power for 15V and 15 VPT output described in Part 3.
Controls output voltage by IC201 and R203 - R205 and transmits control status to primary side by PC1.
41V output section:
Output consisting of D101 and C101 rectifier smoothing circuits.
Serves as the source of power for 41V output described in Part 3.
41V switch output:
Consisting of D601 and C601 rectifier smoothing circuits, 41V switch output serves as source of power for FET Q151 for 41V
output control described in Part 3.
3. Latch Operation Section
Latch circuit for main converter stop due to abnormal state such as excessive output voltage.
Transmits abnormal state detected on secondary side (described in Part 5) to IC1 by PC50 primarily using the IC1 latch func-
tion and stops the main converter by latching.
Latching is canceled 30 seconds after the source of the abnormal state is removed and AC input is off, and is reset to ordinary
operation when AC power is turned back on.
Transmits abnormal state detected on secondary side (described in Part 5) to IC1 by PC50 primarily using the IC1 latch func-
tion and stops the main converter by latching.
Latching is canceled 30 seconds after the source of the abnormal state is removed and AC input is off, and is reset to ordinary
operation when AC power is turned back on.
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KX-NCP500RU
4.6.3.
Output Voltage Section
4.6.3.1.
Describes the circuit that converts main converter output to 15V / 15VPT / 41V.
[1] 15V Output Voltage Section
1. 15V Output Converter Section
The 15V output converter section is a separately-excited chopper step-down converter consisting primarily of IC301, D301,
L301, C301 and R301-R303.
Inputs 32V output described in Part 2 as input power source.
Provides 15V by IC301 and D301 on/off switching and L301/C301 smoothing circuit.
Output voltage is determined by resistance ratio of IC301 and R301-R303.
IC301 oscillation frequency is 70 kHz (typ.).
L301, C301 and R301-R303.
Inputs 32V output described in Part 2 as input power source.
Provides 15V by IC301 and D301 on/off switching and L301/C301 smoothing circuit.
Output voltage is determined by resistance ratio of IC301 and R301-R303.
IC301 oscillation frequency is 70 kHz (typ.).
2. 15V Output Overcurrent Protection Section
Protection is provided by overcurrent protection circuit in IC301.
[2] 15VPT Output Voltage Section
1. 15VPT Output Converter Section
The 15VPT output converter section is a separately-excited chopper step-down converter that utilizes 15V output and same
IC and consists primarily of IC401, D401,L401, C401 and R401-R403.
Inputs 32V output described in Part 2 as input power source.
Provides 15VPT by IC401 and D401 on/off switching and L401/C401 smoothing circuit.
Output voltage is determined by resistance ratio of IC401 and R401-R403.
IC401 oscillation frequency is 70 kHz (typ.).
IC and consists primarily of IC401, D401,L401, C401 and R401-R403.
Inputs 32V output described in Part 2 as input power source.
Provides 15VPT by IC401 and D401 on/off switching and L401/C401 smoothing circuit.
Output voltage is determined by resistance ratio of IC401 and R401-R403.
IC401 oscillation frequency is 70 kHz (typ.).
2. 15VPT Output Overcurrent Protection Section
Protection is provided by overcurrent protection circuit in IC401.
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KX-NCP500RU
[3] 41V Output Voltage Section
1. 41V Output Section
The 41V output section is a dropper type regulator circuit with 41V output described in Part 2 as input voltage that primarily
consists of Q151, Q154, IC101, R107, R106 and VR101.
Q151 is turned on by 41V SW output described in Part 2; output voltage is stabilized by adjusting voltage between Q151 gate
sources by Q154.
Output voltage is determined by IC101, R107, R106 and VR101.
consists of Q151, Q154, IC101, R107, R106 and VR101.
Q151 is turned on by 41V SW output described in Part 2; output voltage is stabilized by adjusting voltage between Q151 gate
sources by Q154.
Output voltage is determined by IC101, R107, R106 and VR101.
2. 41V Output Overcurrent Protection Section
The 41V output overcurrent protection section consists primarily of R157 and Q153.
If overcurrent flows to R157, difference in electrical potential of R157 is detected, which turns Q153 on and Q151 off, resulting
in drooping characteristic.
If overcurrent flows to R157, difference in electrical potential of R157 is detected, which turns Q153 on and Q151 off, resulting
in drooping characteristic.
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KX-NCP500RU
4.6.4.
Alarm Signal Transmission Section
Part 4 contains a description of the circuit that transmits AC and DC alarm signals.
1. Alarm Circuit Power Source
Consisting primarily of Q501 and D502, the alarm circuit power source stabilizes 41V output voltage described in Part 2 to
approximately 27V.
approximately 27V.
2. AC Alarm Signal Transmission Section
If AC input is detected by the AC voltage detection circuit described in Part 1 (5), Q801 is turned on by secondary side transis-
tor of PC80 being turned on, and a low signal is transmitted to AC alarm output.
On the contrary, if AC input is not detected, Q801 is turned off by secondary side transistor of PC80 being turned on, and
"open" (open collector output) is transmitted to AC alarm output.
tor of PC80 being turned on, and a low signal is transmitted to AC alarm output.
On the contrary, if AC input is not detected, Q801 is turned off by secondary side transistor of PC80 being turned on, and
"open" (open collector output) is transmitted to AC alarm output.
3. DC Alarm Signal Transmission Section
If 15VPT/41V output is output normally, and output voltage detection transistor Q551/Q550 is on, Q901 is turned on and a DC
alarm output low signal is transmitted.
If either 15VPT or 41V output is abnormal, Q901 is turned off by transistor Q551/Q550 being off, and DC alarm output "open"
(open collector output) is transmitted.
alarm output low signal is transmitted.
If either 15VPT or 41V output is abnormal, Q901 is turned off by transistor Q551/Q550 being off, and DC alarm output "open"
(open collector output) is transmitted.
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