March 2000 © TOSHIBA TEC
7-83
DP120F/DP125F Circuit Description
4.3 Line Current Detect Circuit
US/CA/TW models
The line current detect circuit consists of the photo-coupler (PC3), I/OP-1GA (IC7) on the Main
PBA, and other peripheral devices. It detects a dial tone and the hook status of the external
telephone from the current flowing through the line.
When a dial tone is input from the telephone line, current flows through the line and the photo-
coupler repeats turning on and off. This allows the OREVA1 and OREVAB1 to be pulse signals
and input to the I/OP-1 GA to detect the dial tone.
When the handset is lifted from the external telephone, current also flows through the line and
the photo-coupler turns on and off to detect the off-hook status.
Fig. 7-4-7
07-04-03
Signal Name
Type
Active
Description
Destination
OREVA1
I
-
Line 1 Current Detect Signal
I/OP-1 GA
OREVB1
I
-
Line 1 Current Reverse Current Detect
I/OP-1 GA
Signal
Содержание DP120F
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Страница 294: ...March 2000 TOSHIBA TEC 6 7 DP120F DP125F PBA Outline and Sensor Function 3 7 PC I F PBA Fig 6 3 8 06 03 08 ...
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Страница 316: ...March 2000 TOSHIBA TEC 7 7 DP120F DP125F Circuit Description 1 2 Block Diagram 07 01 10 Fig 7 1 7 ...
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Страница 579: ...March 2000 TOSHIBA TEC 9 15 DP120F DP125F Dialing and Communication Procedure b Standard procedure ...
Страница 654: ...DP120F DP125F Troubleshooting 11 42 March 2000 TOSHIBA TEC 2 3 Flow Chart Recommended for Field Service ...
Страница 655: ...March 2000 TOSHIBA TEC 11 43 DP120F DP125F Troubleshooting 2 4 Flow Chart Recommended for Telephone Screening ...
Страница 656: ...DP120F DP125F Troubleshooting 11 44 March 2000 TOSHIBA TEC ...
Страница 699: ...March 2000 TOSHIBA TEC 12 1 DP120F DP125F Appendix Chapter 12 Appendix 1 Sample List 1 1 Protocol Trace List ...
Страница 700: ...DP120F DP125F Appendix 12 2 March 2000 TOSHIBA TEC 1 2 Error Count List ...
Страница 701: ...March 2000 TOSHIBA TEC 12 3 DP120F DP125F Appendix 1 3 Function List for Maintenance ...
Страница 702: ...DP120F DP125F Appendix 12 4 March 2000 TOSHIBA TEC 1 4 Drum Unit ...
Страница 703: ...March 2000 TOSHIBA TEC 12 5 DP120F DP125F Appendix 1 5 Memory Dump List ...
Страница 706: ...SHUWA SHIBA PARK BLDG A 2 4 1 SHIBA KOEN MINATO KU TOKYO 105 8524 JAPAN ...