Operation Of Dc Output Circuits - Toshiba e-STUDIO2500c Service Manual

17.2 Operation of DC Output Circuits

1) Starting line output
When the main switch of the equipment is turned ON, power starts supplying to all the lines only
when two covers (front cover and automatic duplexing unit) are closed.
2) Stopping line output
When the main switch of the equipment is turned OFF, PER-DN signal is output after the instanta-
neous outage insurance time (20 ms or more) elapses and then the supply of each voltage stops. If
the supply of voltage of the main switch line (+3.3VA, +5.1VA, +12VA) stops earlier than the 24 V
line does, it may cause the damage of the electron device on each control circuit. To prevent this,
the supply of these voltages stops after the PWR-DN signal is output and the minimum retaining
time (+3.3VA/+5.1VA: 50 ms or more, +12VA: 5 ms or more) elapses.
3) Output protection
Each output system includes an overcurrent and overvoltage protection circuits (a fuse and internal
protection circuit). This is to prevent the defectives (damage or abnormal operation of the secondary
circuit) which may be caused by an overcurrent due to a short circuit or an overvoltage due to a
short circuit between different voltages. If the protection circuit is activated (except the case the fuse
is blown out), remove the causes such as short-circuit. Turn ON the power again 1 minute later to
clear the overcurrent protection.
e-STUDIO2500c/3500c/3510c POWER SUPPLY UNIT
17 - 2
May 2006 © TOSHIBA TEC