Panasonic KX-FT982CA / KX-FT984CA / KX-FT988CA Service Manual ▷ View online
45
KX-FT982CA-B / KX-FT984CA-B / KX-FT988CA-B
6.13. Power Supply Board Section
This power supply board uses the switching regulator method.
[Input Circuit]
The input current goes into the input rectifier circuit through the filter circuit. The filter circuit decreases the noise voltage and the
noise electric field strength.
The input current goes into the input rectifier circuit through the filter circuit. The filter circuit decreases the noise voltage and the
noise electric field strength.
[Rectifier Circuit]
The input current is rectified by D101,D102,D103 and D104 and charges C106 to make DC voltage. Then it supplies power to the
converter circuit.
The input current is rectified by D101,D102,D103 and D104 and charges C106 to make DC voltage. Then it supplies power to the
converter circuit.
[Kick-on voltage circuit]
Bias is applied to the Q101 gate via this circuit when the AC power is turned on and Q101 begins operating.
Bias is applied to the Q101 gate via this circuit when the AC power is turned on and Q101 begins operating.
46
KX-FT982CA-B / KX-FT984CA-B / KX-FT988CA-B
The following is an overview of how the power supply unit is controlled.
The control method of this power supply unit is pulse width modulation.
The control method of this power supply unit is pulse width modulation.
When Q
1
is ON, the energy is charged in the transfer primary coil according to E
1
. When Q
1
is OFF, the energy is output from the
secondary transfer as follows.
L
L
→ D
1
→ Load → L
Then the power is supplied to the Load. When Q
1
is ON, power is not output from the secondary side. The output voltage is fed
back in the control IC according to the error amp rectifier. Then depending on how T
ON
is controlled, stabilization occurs. Also,
when the current load becomes too large, in order to decrease the voltage output, the increase in
is controlled and the output
voltage is stabilized.
Therefore, basically the timing: Ton/Toff of Q1 controls the output voltage.
Therefore, basically the timing: Ton/Toff of Q1 controls the output voltage.
47
KX-FT982CA-B / KX-FT984CA-B / KX-FT988CA-B
[Surge Absorber Circuit]
This circuit is for absorbing surge voltage generated by the transformer.
This circuit is for absorbing surge voltage generated by the transformer.
[Control Circuit and Detecting Circuit]
The control circuit amplifies the output with increased voltage detected in the error detecting circuit. Then it drives the main transis-
tor.
In this power supply, the duty ratio is defined by changing the ON period of the main transistor.
This is shown as follows.
When the output voltage of the 24V circuit increases, the current of the photo coupler PC101 increases, the pulse width of the out-
put control IC becomes narrower and the ON period of Q101 becomes shorter.
The control circuit amplifies the output with increased voltage detected in the error detecting circuit. Then it drives the main transis-
tor.
In this power supply, the duty ratio is defined by changing the ON period of the main transistor.
This is shown as follows.
When the output voltage of the 24V circuit increases, the current of the photo coupler PC101 increases, the pulse width of the out-
put control IC becomes narrower and the ON period of Q101 becomes shorter.
[Over Current Limiter (O.C.L)]
The highest drain current (Q101) is limited by a limiter circuit (IC101) of 24V. The 24V output is limited by this circuit.
The highest drain current (Q101) is limited by a limiter circuit (IC101) of 24V. The 24V output is limited by this circuit.
[Over Voltage Circuit]
If the 24V output increases because the error detecting circuit or control circuit is broken, IC101 will recognize this signal and output
becomes 0V.
If the 24V output increases because the error detecting circuit or control circuit is broken, IC101 will recognize this signal and output
becomes 0V.
Dummy load method (to quickly check the power supply output)
Refer to Power Supply Board Section (P.119).
48
KX-FT982CA-B / KX-FT984CA-B / KX-FT988CA-B
7 Location of Controls and Components
7.1.
Overview
(1) Speaker
(2) Document guides
(3) Paper stacker (KX-FT984/KX-FT988 only)
(4) Document feeder tray
(5) Top cover
(6) Document exit
(7) Document entrance
(8) Top cover release button
(2) Document guides
(3) Paper stacker (KX-FT984/KX-FT988 only)
(4) Document feeder tray
(5) Top cover
(6) Document exit
(7) Document entrance
(8) Top cover release button
7.2.
Control Panel
(1) [AOH]
• To use Caller identification features.
(2) [STOP]
• To stop an operation or programming session.
• To erase a character/number. Press and hold to erase all
• To erase a character/number. Press and hold to erase all
characters/numbers.
(3) [FLASH]
• To access special telephone services or for transferring
extension calls.
(4) [REDIAL/PAUSE]
• To redial the last number dialled. If the line is busy when
you make a phone call using the [MONITOR] (KX-FT982/
KX-FT984)/[DIGITAL SP-PHONE] (KX-FT988) button,
the unit will automatically redial the number up to 3 times.
KX-FT984)/[DIGITAL SP-PHONE] (KX-FT988) button,
the unit will automatically redial the number up to 3 times.
• To insert a pause during dialing.
(5) [RECORD] (KX-FT988 only)
• To record your greeting message.
• To record a telephone conversation.
• To record your voice memo.
• To record a telephone conversation.
• To record your voice memo.
(6) [ERASE] (KX-FT988 only)
• To erase messages.
• To erase a stored item.
• To erase a stored item.
(7) [PLAYBACK] (KX-FT988 only)
• To play messages.
KX-FT982 / KX-FT984
KX-FT988
(1)
(2)
(3)
(4)
(8) (9)
(10) (11)
(13)
(12)
(14)
(17)
(19) (20) (21)
(18)
(10) (11)
(13)(15)(16)(17)
(18) (19) (20) (21)
(12)
(1)
(2)
(3)
(4)
(5) (6) (7) (8) (9)
1
6
2
7
3
8
6
2
7
3
8
4
9
5
9
5
10
10
FLASH
REDIAL /
PAU
AUSE
SE
COPY
OPY
AUTO ANSWER
AUTO ANSWER
MENU
MENU
PHONEBOOK
PHONEBOOK
BROADCAST
TONE
TONE
VOLUME
HANDSET
MUTE
MONITOR
MONITOR
ONE-TOUCH DIAL
ONE-TOUCH DIAL
STOP
TOP
1
6
2
7
3
8
6
2
7
3
8
4
9
5
9
5
10
10
FLASH
REDIAL /
PAU
AUSE
SE
COPY
OPY
AUTO ANSWER
MENU
PHONEBOOK
BROADCAST
BROADCAST
TONE
TONE
VOLUME
MUTE
RECORD
ERASE
PLAYBACK
DIGITAL SP-PHONE
DIGITAL SP-PHONE
MIC
MIC
ONE-TOUCH DIAL
ONE-TOUCH DIAL
STOP
TOP
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