Muratec MFX-2550 Field Engineering Manual page 49

High-voltage power board
This board generates high-voltage power required for electrophotographic system ; charge, develop-
ing, transfer, and cleaning sections.
In charging section, it generates positive voltage which is applied to the wire in the drum unit in order
to charge the drum surface positive. It monitors the charge condition through the wire condition. Also it
charges the mesh grid electrode at the opening of charger in order to make the drum charge potential
even.
In developing section, it generates positive voltage which is applied to the developing roller and supply
roller in the developing unit in order to transfer the toner in the developing unit to the drum. The con-
trol of output voltage is made by an analogue signal.
In transfer section, it generates negative voltage which is applied to the transfer roller in order to trans-
fer the toner on the drum to paper. The control of output voltage is made by an analogue signal. Also
generates positive voltage when cleaning the transfer roller.
In cleaning section, it generates positive voltage which is applied to the cleaning roller and cleaning
shaft in order to collect paper dust on the drum.
Network Control Unit (NCU) board
The NCU board provides the connection to the telephone line. It consists of the interface circuit, ring
signal detector and telephone control circuit.
Major components of the NCU
DP relay
Connects the telephone line to the fax.
S relay
Used to connect the telephone line at seizure state.
OH & Tone detector
Detects the On-hook condition of the Phone 1 and Phone 2.
H relay
Disconnects the Phone 1 and Phone 2 line from PSTN.
24V generator
Supplies 24 volts to the relays for OH detection of Phone 1 or Phone 2.
Ring signal detector
A photo coupler that detects an incoming ring.
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