Toshiba DP120F, Service Manual

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DP120F/DP125F Circuit Description 7-90 March 2000 © TOSHIBA TEC
Fig. 7-4-13
07-04-06
4.6 Hook Detect Circuit (US/CA models only)
The hook detect circuit consists of the hook switch (HS1) installed on the TEL PBA, I/OP-1 GA
(IC7) on the Main PBA, and other peripheral devices to detect the hook status of the handset.
The hook detect circuit is provided on the US/CA models only.
When the handset is replaced, the hook switch is pushed down by the handset. This causes
the OHOOK1 signal to be HIGH and input to the I/OP-1 GA to detect that the handset is
replaced.
The hook status of the external telephone is detected by detecting current flowing through the
line by the line current detection circuit when the handset is lifted.
Signal Name Type Active Description Destination
OHOOK1 I H Hook Detect Signal I/OP-1 GA