Panasonic Va-208 Key Telephone System Installation Manual

							(3) 
(4) 
(5) 
1) Intercom call tone sounds and intercom voice call. 
When the intercom call sounding signal and voice call signal is sent to the TEL from the KSU, pin (36) of ICI 
becomes @ level. The @ level-signal is sent to pin (5) of IC5 via D4 and turns IC5 to ON. The following opera- 
tion is the same as in clause 2.2. 
Interrupt tone control and interrupt tone output. 
The interrupt tone control signal is sent to the TEL from the KSU, pin (23) of ICI becomes @ level, then the 
receiving SW at busy IC5 (pin I,21 is turned to ON at the @I level on IC5 (Analog switch). 
The interrupt tone is sent to the speaker by the following path. 
ICI (27) + 05 (Amplify) -+ IC5 (1) 
-+ ICI (2) + IC6 (Amp.) + Speaker. 
Key-in tone control and Key-in tone output. 
Handset output 
l When the handset is OFF-hook, the off-hook detection signal is sent to the KSU with input the @ on pin 
(16) of ICI by HS3. 
When the dial key is pressed pin (22) of ICI outputs @ + the @ level on pin (12) of IC5 then turns the 
Key-in tone switch IC5 (10, 11) to ON. 
l The Key-in tone output is outputted from the receiver when the dial key is pressed by the following path. 
ICI (27) + Q5 (Amp.) + IC5 (11) + IC5 (10) --f Cl3 + T2 + Receiver 
2) Speaker output 
a When the dial key is pressed, the @ level-signal is outputted from pin (22) of lCl,which turns the Key-in 
tone switch IC5 (10,ll) to ON with the $J level on pin (12) of IC5. 
l Key-in tone is output from SP when the dial key is pressed by the following path. 
05 (Amp.) + IC5 (11) + IC5 (10) + R37 -+ R34 + IC5 (9) -+ IC5 (8) + IC6 (Amp.) + SP 
1.3 Power supply for TEL 
To speakerphone unit 
CHI 
Ql 
HO m 
+ 3 
D18 1 zzc2 Z: C28 + 
IIC4 
Data Communication +7v 
+5v 
+12V DC is supplied from the KSU to the TEL. Supplied voltage is converted to +7V and +5V by the voltage 
regulator circuit and converted voltages are used for the power source of the TEL. 
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							1.4 A-K communication 
Data communication between KSU (CPU) and TEL (APU) 
+5v 
T---i R4 
c5 
Lo +H 7 
” - 
PTi 
(I) 
(2) Receiving of A-K communication 
(pin NO. 13 of ICI) A4 P30 
= I3 P23 
:I5 P31 
= 3.iKi 
K=. PF2 
The receiving signal from H and L line is received by ICI via the following path. 
PTI (Signal induced) -+ R9 -+ Q3 + IC3 (6) 
NOTE: 
DC current is eliminated by C5 and C6. D2 is a half wave rectifier. 
Pin (15) of ICl receives the signal from the KSU only when the @ level-signal appears on the A-K communica- 
tion receiver control terminal from pin (13) of ICI. 
Transmitting of A-K communication data 
The data of the TEL is sent to H and L line from pin (14) of ICI via the following path. 
IC2 (4) + 02 (Base) --f Q2 (Collector) + PTI (9, 10) -+ PTI (6, 7) + C5 and C6. 
1.5 Speech path change circuit 
ICI 0 
0 
When the SPKR button is pressed, the voltage level at pin (21) of ICI on the main P.C.B. (PB3942) becomes 
@I and the relay S is caused to operate via the following path. 
ICI (21) @I + 01 (ON) + Q2 (ON) + Relay S 
Thus, the speech path is changed from the handset to the speakerphone. Note here that 010 and ZDI 
are used 
for obtaining a +8V stabilized power source, 
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							1.6. Transmitting circuit (speakerphone) 
R20 
AnA 
-tw 
Q6 
RI9 
When the SPKR button is pressed, pin (20) of ICI on the main P.C.B. (PB3942) becomes (@ causing Q5 and 06 
to be turned ON and the power to be supplied to the MIC. 
The send voice signal is connected to the COL via the following path. 
MIC -+IC6-+ IC2-+VR2’lCl +Tl -+COL 
In addition, the send voice signal is also input to the Voice SW via the following path. 
MIC+ IC6+ IC2-+VR2-+ ICI +Voice SW 
If there is any receive signal, since the voltage level at pin (6) of IC2 is caused by the Voice SW to drop, the send 
signal level also becomes low.  
						

							1.7 Receiving circuit (speakerphone) 
Sendvoice signal 
P 
vss 
I SP AMP 
I R50 I 
_L 
c55 7 R45 ICI 
I I IC4 
I 
I c4 I 
R2”’ , A6 _ 
r-v--i_ 5+ R3 +av 
The received voice signal is connected to the speakerphone via the following path. 
COL + ICI + VRl + IC2 -+ CN5 (8), Main P.C.B. + IC6 + Speakerphone 
In addition, the received voice signal is also inputted to the Voice SW via the following path. 
COL + ICI + IC4 + ICI + Voice SW 
If there is any send signal presente, pin (13) of IC2 (Voice SW) goes 0 
, causing the receive signal to be cutoff 
at IC2. 
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