Panasonic KX-TEA308RU / KX-TE82460X / KX-TE82492X / KX-TE82493X / KX-A227X Service Manual ▷ View online
1) Conference switch
Normally, pin 6 of the analog switch IC2 is low level, but during conferences, this pin becomes high level. Because, during
conferences, it should compensate the return loss by connecting the balance network BN2 and the balance network BN3 in
parallel.
conferences, it should compensate the return loss by connecting the balance network BN2 and the balance network BN3 in
parallel.
2) Mute switch
The mute switch consists of pin 13, 1 and 2 of the analog switch(IC2). This switch has the following functions.
a) When a dial signal (DP) is sent to the COL, signals from the extensions are blocked.
b) When the hold on music is sent to the COL, signals from the extensions are blocked.
c) When the COL interface circuit is in the idle state, oscillation of COL bidirectional amplifier is inhibited. When pin 13 of IC2
changes to low level, the interval between pins 1 and 2 of the analog switch turns off, and signals are blocked.
a) When a dial signal (DP) is sent to the COL, signals from the extensions are blocked.
b) When the hold on music is sent to the COL, signals from the extensions are blocked.
c) When the COL interface circuit is in the idle state, oscillation of COL bidirectional amplifier is inhibited. When pin 13 of IC2
changes to low level, the interval between pins 1 and 2 of the analog switch turns off, and signals are blocked.
3) Shunt switch
The shunt switch consists of pin 12, 10 and 11 of analog switch IC2.It is used to prevent the pulse dialing signal which is
transmitted to the extensions. When pin 12 of IC2 changes to high from low, the analog switch becomes ON (the interval
between pin 10 and 11), and GAIN of the COL cross point operational amplifier becomes zero.
transmitted to the extensions. When pin 12 of IC2 changes to high from low, the analog switch becomes ON (the interval
between pin 10 and 11), and GAIN of the COL cross point operational amplifier becomes zero.
Shunt SW
Mute SW
Conference SW
pin no. of analog switch
12
13
6
No connection (idle)
H (on)
L (off)
L (off)
Two party call
L (off)
H (on)
L (off)
Conference
L (off)
H (on)
H (on)
Hold on music transmission
H (on)
H (on)
L (off)
Condition of COL interface amplifier circuit and analog switches.
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11.3. CROSS POINT SWITCH CIRCUIT
11.3.1. Composition
The cross point circuit composed of three cross point switch IC´s (IC601:8X16, IC602 and IC603:4X8).
1) Cross Point Switch IC Operation
1) Cross Point Switch IC Operation
The cross point SW (IC601) contains a 8X16 array of cross point switches along with a 7 to 128 line decoder and latch circuits.
Any one of the 128 switches can be addressed by selecting appropriate seven address bits. The selected switch can be turned
on or off by applying either logical one or zero to the DATA input. Chip select allows the cross point array to be cascaded for
matrix expansion.
The cross point SW´s (IC602, IC603) contain 4X8 array of cross point switches along with a 5 to 32 line decoder and latch
circuits. Any one of the 32 switches can be addressed by selecting appropriate five address bits. The selected switch can be
turned on or off by applying either logical one or zero to the DATA input. Chip select allows the cross point array to be cascaded
for matrix expansion.
Any one of the 128 switches can be addressed by selecting appropriate seven address bits. The selected switch can be turned
on or off by applying either logical one or zero to the DATA input. Chip select allows the cross point array to be cascaded for
matrix expansion.
The cross point SW´s (IC602, IC603) contain 4X8 array of cross point switches along with a 5 to 32 line decoder and latch
circuits. Any one of the 32 switches can be addressed by selecting appropriate five address bits. The selected switch can be
turned on or off by applying either logical one or zero to the DATA input. Chip select allows the cross point array to be cascaded
for matrix expansion.
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KX-TEA308RU
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KX-TEA308RU
11.4. INTERCOM CIRCUIT
11.4.1. INTERCOM CIRCUIT
1) Composition
This is composed of the following circuits:
a) +15V power source for the extension telephones
b) Hook detect for SLT and pulse dialing detect
c) Bell ring trip section
a) +15V power source for the extension telephones
b) Hook detect for SLT and pulse dialing detect
c) Bell ring trip section
2) Circuit operation
a) Power supply to the telephone
With the telephone off hook, a DC loop is formed, and current is supplied to the telephone. This circuit is limited to about 30mA
by Q200, Q202, R202, R204 and Q201, Q203, R203, R205.
+27V
With the telephone off hook, a DC loop is formed, and current is supplied to the telephone. This circuit is limited to about 30mA
by Q200, Q202, R202, R204 and Q201, Q203, R203, R205.
+27V
→R204→R202→Q200→RL201→telephone→RL201→Q201→R203→R205→AG
b) Hook detect for SLT and pulse dialing detect
When the telephone handset is taken off, DC loop is formed and the collector of U200 3,6 pin change to L from H.
And IC7 detects the off hook condition.
When the handset is replaced back on hook, the DC loop is interrupted and collector of U200 3,6 pin change to H from L and
EXT Pulse dialing is input either in the on hook or off hook condition, and the break number (on hook condition) is counted and
read as the dial number.
c) Bell ringing trip section
When the telephone is a signal line telephone, extension calling is executed by means of a ringing signal. When the ringing
signal is supplied, RL201 turns ON and the current flows are as follows:
Bell generation circuit
When the telephone handset is taken off, DC loop is formed and the collector of U200 3,6 pin change to L from H.
And IC7 detects the off hook condition.
When the handset is replaced back on hook, the DC loop is interrupted and collector of U200 3,6 pin change to H from L and
EXT Pulse dialing is input either in the on hook or off hook condition, and the break number (on hook condition) is counted and
read as the dial number.
c) Bell ringing trip section
When the telephone is a signal line telephone, extension calling is executed by means of a ringing signal. When the ringing
signal is supplied, RL201 turns ON and the current flows are as follows:
Bell generation circuit
→ ringing signal line → RL201 → telephone → R206 → AG → Bell generation circuit
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KX-TEA308RU
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