Explanation Of Circuit Operation - Toshiba 1550 Service Manual

15.2 Explanation of Circuit Operation

(1) DC + 24V
The +24V system, which is a rated voltage circuit based on the switching method, is always controlled to
provide a fixed output voltage by feeding back fluctuation in the output to the primary side through a
photocoupler.
(2) DC + 5V
The +5V system is for providing a regulated 5V output by stabilizing the voltage from the 5V winding by
means of a 3-terminal regulator.
The following shows the output sequence of the power supply.
ON
AC inputs
500ms or less
+5V
+24V
ACOFF
Zero cross
1550/1560 POWER
4.75V or more
21.6V or more
0~5ms or less
15 - 2
OFF
4.75V or
more
21.6V or more
20ms or
more
10ms or more
Mar. 1998 © TOSHIBA