Panasonic Va-208 Key Telephone System Installation Manual

7. TONE Circuit 
7.1 450Hz oscillator circuit: 
Used for Intercom call tone. 
7.2 550Hz oscillator circuit: 
Used for Intercom dial tone, Busy tone and Ring back tone. 
7.3 16Hz oscillator circuit: 
Used for CO incoming call tone which modulated with 450Hz/550Hz by 16Hz. 
-8-  

8. Link IC Circuit 
Intercom Speech path 
Intercom Incoming Call Tone.RT 
.: 
COL 1 Speech Path 
COL 2 Speech Path 
Door Intercom Speech Pat 
+3v t RAI 
, 
ITT 
B 
To Extension Card 
(Used for TEL 5 to 8) 0 
: 
-il 
4c 
5 
6 
7 
Release and connection of TEL and IC (IC9 to ICI I). 
Release and connection between TEL and link IC is executed by control data from lC6. 
The control data output from IC6 is output to STR, DO, A to E pin terminal of 1%. 
The operation of the data input to IC9-ICI 1 (STR, DO,...

Link IC (MN6105) operation 
Cross point I 
To Extension Card 
(Used for TE L5 to 8) 
NOTES: . 
When the status of 
and DO (pin No.4) 
of A to E and ratch 
When the status of Link IC input terminal SRT (pin No. 10) 
is @ 
, Link IC read out the address data 
the cross point. NC = Keep the present operation. 
ON = Ratch 
Link IC input terminal SRT (pin No. IO) OFF = Release the ratch. 
is @ and DO (pin 1No.4) is 0, Link IC read the address 
data of A to E and release the ratch of cross point. 
In case of...

9. Data 
Communication between TEL and KSU (1) 
Circuit 
3 
( H 
L 
rlloo 
T --_  TEL 
No. 1 
* 12v 
RI03 
+ Cl02 
9.1 
(11 
(2) 
9.2 
Dato 
Communication 
6J.J 
I HBl (HB2006) Circuit 
+ c4 
RI7 RI9 LT 
05 -14 
RI6 
015 
016 
D3 R21 
R22 R20 
I + c5 
R23 
R25 
07 -17 
R24 
016 
019 
D4 
R26 R27 
R26 
Supply of the control current to H, L terminal. 
(For data communication and power supply 
source to the TEL). 
+lZV is supplied to H,L terminal via CHIOI choke coil, and supplied DC voltage is superpaused...

10. Data Communication between TEL and KSU (2) 
T301 
T401 
ICl (RST) IC4 
t 
Interrupt data input 
Control from TEL 
Data output to TEL 
Inhl (TEL1 ~4) 
Inh2 (TEL5-8) 
Data input from TEL 
I 4 
3 3 IC6 
10.1 The circuit for read in the data from TEL to KSU. 
The data sent from TEL is input to HBI (pin No.4) and output it from HBI (pin No. 11). The output data is in- 
put to ICY (pin No. 13) via D15 (Low active). The input data of IC21 (pin No. 13) is input to IC21 (pin No.9) 
through pin No. 11 when @...

11. IC Port Explanation 
11.1 IC4 (UPD8255AC) 
COL 2, Incoming call COL 2, Incoming call detection 
COL 2 seize 
COL 2, ON status on dialing(DP/DTMF) 
COL 1, Hold tone sending 
atus on disable 
ata output from KSU to TEL/@ -1, 0 
-0 
late : All letters for I/O is “in” or “out”. H 
: enable L : disable 
- 13-  

11.2 IC5 (UPD8255AC) 
SLT dialing output. (eg. No.7 dialing 
0 status on port A4, 5, 6) 
on Power ON 
13 
12 
11 
10 4 
DPH Busy 
@status on Normal/O status on Busy 
5 DPH Sel 
@status on B selection/@ status on A selection 
6 EPA lontal 
@status on Normal/@ status on EPA 
1 SPC (TEL 3 to 8 on power faiIure)@status on 
power failure/@ status on Normal 
- 14-  

11.3 IC6 (UPD8255AC) 
(@ status on CO line seizure/@ status on  

W EXPLANATION OF CIRCUIT OPERATION (KEY TELEPHONE) 
1. Conversation 
Hand set (Transmitter and Receiver) is connected to T, R line when HSI is [ON] (OFF-HOOK). 
T 
I, 
HSl 
+ 
+ 
MIC 
- 
Incoming Signal 
R36 
, 
R24 
R21 R22 
08 izC15 
: R33 
1.1 Receiving 
The voice signal input is emitted from receiver via the sequence of: 
T, R terminal + HSl 
[ONI -+ DBI (Rectifier) + Sink circuit (Provided to maintain conversation quality by 
constant current 
supply for various distance condition to the Central...

2. Functional Operation Circuit 
HS3 b 
I $R26 
/ 
1 f SPKRL PF3 
P70 
P71 
P72 
P73 
1 
2.1 
CO lamp flickering during CO line talk (eg. COL 1). 
When CO incoming call lamp data is arrived to TEL from KSU, ICI pin No.32 is output the control data (0.5 
sec. @ , 0.125 sec. @@@ and 1.5 set 0). The lamp control data turn on the COL lamp when the status is 
@and turn off the COL lamp when the status is @ 
. This is the reason for COL lamp is flickering. 
2.2 
Sounding of CO incoming call tone. 
When the CO...