Dc Power Supply Is Absent - Canon NP6251 Service Manual

CHAPTER 11 TROUBLESHOOTING

31. DC power supply is absent.

Cause Step
AC power
supply
Wiring, DC load
DC power
supply PCB
11-100
COPYRIGHT © 1997 CANON INC.
Checks
1 Is the specified voltage present
between J301-1 and J301-5,
between J301-3 and J301-5, and
between J302-1 and J302-3?
(J301 and J302 are in the DC
power supply unit.)
2 Has the fuse (FU51, FU1) on the
DC power supply blown?
3 Turn off the power switch, and dis-
connect the power plug. About 1
min thereafter, connect the power
pug. Is DC power present when
the power switch is turned on?
4 Turn off the power switch, and
disconnect all connectors from the
DC power supply PCB (J303,
J304, J305, J306, J308, J309,
J311). Turn on the power switch,
and measure the voltage between
the terminals shown. Is it as
indicated?
Connector Pin
1
J303 2
3
2
J304
4
1
3
J305
5
7
J306 1
1
J308 3
5
1
J309
3
1
J311
2
However, the above assumes that
the inaccuracy of the AC input is
±10%.
YES/NO
Output Remarks
38VU +10%,-7%
38VU +10%,-7%
38VU +10%,-7%
24VR ±2%
24VU +10%,-7%
24VU +10%,-7%
24VR ±2%
5VR ±4%
12VU +10%,-7%
24VU +10%,-7%
24VU +10%,-7%
24VA +10%,-20%
38VU +10%,-7%
24VU +10%,-7%
24VU2 +10%,-7%
24VA2 +10%,-7%
38VU +10%,-7%
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
Action
NO See "AC power is
absent."
YES Remove the cause, and
replace the fuse.
YES End.
YES Turn off the power
switch, connect one of
the disconnected con-
nectors, and turn on the
power. Repeat this for all
connectors to find the
one which activates the
protection circuit. Check
the wiring and DC loads
from that connector.
NO Replace the DC power
supply PCB.