Toshiba GD-1150 Service Manual page 74

EU/AU/AS/C models
NCU board
Lb
4
Line
The line current detection circuit consists of the line current detection IC (IC2), ASIC (IC29 [IC26]) on
the FAX board, and the other peripheral devices. It detects a dial tone and the hook status of the exter-
nal telephone from the current flowing through the line.
When a dial tone is input from the telephone line, current flows through the line. The line current detec-
tion IC sends REVA1 and REVB1 to the ASIC as pulse signals. This allows a dial tone to be detected.
Signal Name Type
REVA1 I
REVB1 I
* Values in [ ] are for GD-1151/1201 in case that the descriptions vary between GD-1150/1200 and
GD-1151/1201.
GD-1150/1151/1200/1201/1160/1260
ELECTRICAL CIRCUITS
1 8
IC2
Line current
detection
IC
R26
2 7
Fig. 4-12
Active
- Line 1 Current Detection Signal
- Current Reverse Line 1 Current Detection
Signal
4 - 12
08/03
FAX board
19 19
20 20
Description
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REVA1
2
IC29
[ IC26 ]
ASIC
REVB1
3
Destination
IC29 [IC26]
IC29 [IC26]