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(2-1) THE SWITCHING REGULATOR UNIT FAILURE
Turn off the power switch. After one minute, disconnect CN-K,
then turn on the power switch.
Measure the voltage across K4-K1 (+170V output) and across
K4·K3 (+24V output) with a digital multimeter (DMM).
NO
' .
Approx. 170V measured across K4-K 1,
YES
Check D653 and L653
j
but 0V across K4-K3
- -
NO
'
Approx. 24V measured across K4·K3,
YES
Check D651 and L651
j
but 0V across K4-K1
-
NO
'
More than 18V measured across pins 13
YES
Check D652, PC601, ZD657, ZD602,
and 16 of IC601
-
IC601, IC651, 0604, ZD658,
and PC602
NO
,,
The voltage across IC601 pins 13 and 16 is
YES
Check 0601, ZD601, D604, R614,
fluctuating from approx. 10V to 16V
R610
NO
,
The voltage across IC601 pins 13 and 16
YES
Check IC601, C611, C619,
measured between 1 V and 9V
-
and ZD602
'
NO
I
The voltage across "+" and "-" terminals
YES
Check R603, R630
of D601 is approx.
-
NO
t'
Check 0603, IC601, D601, R601,
.,
YES
Fuse F601 is blown N
-
R610, R611, R616,and
R617
NO
t'
Check D605, R624, R627, CR601, 0603,
YES
IC601, R610, R611, R616,
·-
R601 is burnt out
-
.-
I
R617, C605, C606 and C612
--
-30-
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