Samsung SF6500 Service Manual page 83

Circuit Description
5-8-5 MF/DP Dialing
DP dialing is activated by receiving digital data
from CPU through UART Tx. The signal turns on
and off Q2 through ILIU chip and DPN. It causes
Q1 to be on and off to generate the dial pulse.
MF dialing is activated by receiving digital data
from CPU through UART Tx. ILIU chip adjusts
DTMF frequency and level through RFO and RFI
and sends out the DTMF signal.
Q1
Q2
Figure 5-9 MF/DP Dialing
5-6
39
LS
RFO
37
LI
35 4
RFO
CS
Q3
R20
9
RFI
27
DDN
R21
C14
C15
5-8-6 Remote Receive
This circuit switches the machine to automatic
receive mode when it detects *2* key input from
the phone extension.
TIP
RING
EXT
LINE
Figure 5-10 Remote Receive
Remote RCV
Samsung Electronics