Power Supply Circuit - Canon NP6251 Service Manual

CHAPTER 7 EXTERNALS/AUXILIARY MECHANISMS
B. Power Supply Circuit
The machine's DC power supply provides DC outputs: 38 VU, 24 VU, 24 VR, 24 VA1,
24 VA2, 24 VH, 12 VU, and 5 VR.
The AC power supply consists of (a) an AC direct input line without a switch, (b) an
input line by way of a power supply switch SW1, (c) an input line by way of power switch
SW1 and door switch SW2, providing the DC power supply with DC AC power through
three channels.
When the power switch SW1 is turned on, each power supply circuit is provided with
AC power to generate a DC output; the 5VR, 12VU, and 24VA1 power supply circuits are
controlled so that the input lines are switched by the remote signal (RMT) from the DC
controller PCB.
When the power switch SW1 is turned on, each power supply circuit is provided with
power through the line which leads through the power switch SW1 (line b), thereby
turning on the microprocessor on the DC controller PCB; thereafter, the microprocessor
on the DC controller PCB causes the remote signal RMT to go '1' turning on the relay
RL401 so that the AC input line will switch to the AC direct input line (a).
The 38VU, 24VU, 24VR, 24VA2, and 24VH circuits turn off when the power switch
SW1 is turned off; other DC power circuits, however, remain on to continue to supply the
DC controller PCB with DC power, thereby keeping the fans rotating for a specific period
of time (about 15 min); thereafter, the DC controller PCB causes the remote signal RMT
to go '0' to cut off the AC circuits, thereby automatically shutting off the AC inputs to the
DC power supply circuits.
Caution:
Check to make sure that the power plug is disconnected always before working on
the DC controller, as for replacement.
7-10
COPYRIGHT © 1997 CANON INC.
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CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)