Toshiba e-STUDIO 206, Service Manual

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e-STUDIO166/206 © February 2007 TOSHIBA TEC CORPORATION All rights reserved
POWER SUPPLY UNIT
14 - 2
14.2 Operation of DC Output Circuit
1) Starting line output
When the power of the equipment is turned ON, all the voltages start being supplied. However, they
start being supplied only when both the front cover and the ADU cover are closed.
2) Stopping line output
When the power of the equipment is turned OFF, the power-OFF (PWRDWN-1) signal is output after
the end of the instantaneous outage insurance time (20 ms or more), and then the supply of each
voltage stops. If the supply of voltage of the +5VB line stops earlier than the 24V line does, it may
cause damage to the electron device on each control circuit. To prevent this, the supply of the +5VB
voltage stops after the power-OFF signal is output and the minimum retaining time (50 ms or more)
has elapsed.
3) Output protection
Each output system includes an overcurrent and overvoltage protection circuit (a fuse and internal
protection circuit). This is to prevent defects (damage or abnormal operation of the secondary cir-
cuit) which may be caused by an overcurrent due to a short circuit or an overvoltage resulting from
short-circuiting between different voltages. If the protection circuit is activated (except when the fuse
is blown), repair the causes such as short-circuiting. Turn ON the power again 1 minute later to clear
the overcurrent protection.