Toshiba GD-1220, GD-1221 service manual Line 1 CI Detection Signal IC23

Models: GD-1220 GD-1221

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EU/AU/AS/C models

NCU board

+12V

RLY3

 

 

CML relay

1

12

4 Lb 4

1

 

Q4

3

FAX board

3 CML1 27

MAIN board

27

144

 

 

0

3

Line

CN3

1

 

 

 

 

 

3 La 9

 

 

 

0

10

C8 R4 ZD2 ZD3

D2

AG

5VPS

1 4 R34

PC1

 

17

2

3

 

Q5

R35

SG

CN4

CN262

CN5

17 CI1 65

CN5

IC23

ASIC

65

162

Fig. 4-11

The CI detection circuit consists of the photocoupler (PC1), ASIC (IC23) on the MAIN board and other peripheral devices to detect a ring signal input from the telephone line.

The ASIC makes the CML1 signal become LOW to connect the CI detection circuit to the line. When a ring signal is input from the telephone line, the photocoupler is repeatedly turned ON/OFF. This allows Q5 to be turned ON/OFF and the CI1 signal to become a pulse signal and input to the ASIC on the MAIN board, thereby detecting the ring signal.

Signal Name

Type

Active

Description

Destination

 

 

 

 

 

CI1

I

-

Line 1 CI Detection Signal

IC23

 

 

 

 

 

4

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GD-1220/1221

 

ELECTRICAL CIRCUITS

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Page 71
Image 71
Toshiba GD-1220, GD-1221 service manual Line 1 CI Detection Signal IC23