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4. Trouble shooting procedure of POWER SUPPLY
4-1. Tools required
The following tools are required for servicing.
4. 5V 11.3A and 12V 11.3A loads
1. Oscilloscope
5. AC ammeter and voltmeter
2. Voltage regulator (Slidac)
3. Voltmeter (digital voltmeter)
4-2. When R 1 is open
Since this failure may possibly be due to short circuit of ac line capacitor, RC1, C4, or Q1, the cause has to be checked in
accordance with the flowchart below. -
Flowchart
Phenomenon and others
Replacing component
Gl
Set the oscilloscope to the follow·
(
Start
ing range.
Voltage range:
50V/div
~
Time range:
10us/div
Replace R 1 with the new
one.
®
Shut off the AC
supply immedi-
Replace the following
components
l
Gl
ately, when the ammeter coupled
with new ones in this case, because
Connect the oscilloscope
to the AC line increases abruptly.
there may be possible destruction
in
probes between the
emit~
these components.
ter and collector of Q1.
01, RC1.C4.Cl,C16
~
®
@
Should 01
be found in failure,
there will be need of replacing
Gradually
increase
the
the following components, as they
AC voltage using *Slidac.
may
possibly be in destruction,
too.
~
@
02,03,Dl,D3,Rl1,RS
Replace
the
defective
@
component with the new
Put the load into connection in
NOTE: Should 01 be found
in
fail~
this case and
ensure
that the
ure, there may be possible destruction
one.
following waveform appears.
in RS, too.
When Step (2) is carried
~
@
out with RS in open state, it causes
Gradually
increase
the
r -
to add dc voltage between the collec-
AC voltage using *Slidac
h
tor and the emitter of 01 so that DC
and ensure appearance of
voltage may not decrease even after
the waveform shown in
the ac supply was shut off.
So, care
FIG·2.
320V
must be
exercised
in this case to
~
avoid continuous impression of the DC
Check
proper output of
voltage.
+5V and +12V,
respec-
tively.
-~
-
J,
1--35"S-
(
End
)
(Fig. 2)
* Slidac
=
Variable Voltage transformer
-5-
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