Summary of Product
4.6 LIU PBA
LIU board is a Line interface unit, and it is a circuit for interfacing a telephone line with a modem. The circuit is consist-
ed of matching transfer to conform to impedance of a receiving telephone line and a circuit to conform to impedance of a
modem.
Also, there is a ring detect circuit to detect a ring signal from a switchboard and a surge absorber to protect it from an
external high voltage supply applied to a line input unit.
4.7 OPE PBA
OPE board is consists of various function keys and LCD to display an operation of key. MICOM creates
a circuit with using HT48R50 MICOM of HOLTEC CO. and applies LED and LCD. A communication
method with a CPU of a main board is UART, and related signals are /Reset, TXD, and RXD.
Service Manual
4-20