HP 4262A Operating And Service Manual page 220

-12vis
Measure voltage at AOTP4 with
YES
Measure voltages at A9TP5 and | NO
out of range.
1s voltage across ASCS more | NO
Check A9C5, ASCR2,
voltmeter.
Is it within +11.95
A9TPS.
Are they within the
than 4Vdc ?
Ti, etc.
to +12. 05vdc ? following ranges ?
-12. 15V thru -11. 85V (A9TP5) YES
+4.85V thru +5. 15V (A9TP6)
YES l
Does voltage at A9U3 pin 6
| NO_|
Check A9U3, A9R10-
NO
change when A9RS is
RIl1, C9, etc.
Do the following dc voltages exist
adjusted?
at A9TP3 when DC BIAS switch is
operated?
+1.425 thru 1.575V (1.5V) YES
Can voltage at A9TP4 be set
§YES | Adjust at ASTP4 to +12V
+2.09
thru 2.31V (2.2V)
to +11. 95 to +12. 05Vde by
0. 05vde with AGR6.
Then +5.7
thru6.3v ( 6V )
NO
adjusting A9R6 (+12V ADJ.)?
perform all adjustments for
<o
Does voltage at A%Q3 base
Check A9Q2, etc.
42624,
OME
change when A9RS is
ALL ARE FAULTY ARE [ adjusted ?
FAULTY
Check ASR12
YES L
NO
Check A9U4, ete.
thru ASRIT.
Check Q3, ASR4,
ete.
Is voltage across A9C4 more | YES | Does voltage at ASUZ pin 6 YES
than 16Vde ? change with A9R6 adjustment ? —-L Check Q2, ASRZ, etc. ]
NO l
5V is
out of range: Is voltage at A9TP1 more | NO_| Check CRI, CR2,
Check A9U2, A9R5-R7, ASCS,
than 6. 0Vde ?
A9C1-C3, etc.
NO AICS, etc.
YES l
Does voltage at A9U1 pin 6 No Check A9U81-.m:9\9c't7';
Is voltage at ASTP1 more | YES
chz.mge when A9R6 is
CR3, A9R8-R9, etc.
than 6. 0Vdc ?
Check ASCRI1, A9C4, T1 ]
Note
adjusted?
NOI
If the symptom
of the trouble is an excessive
YES—{
ripple (more than 30mVpp for +12V and -12V, NO
Check T1, F1, 81,
line module
and 50mVpp for +5V),
the cause of failure
power cal;le, ete.
'
may be located in error voltage amplifier
Does voltage at ASQL base
Check A9Q1, etc.
(ASU1, Q1, Q3; A9U2; ASU3, Q2, Q4) or the
change when ASRS is
filter capacitors.
H poor voltage regulation
adjusted ?
(dc output voltage changes over §.05 volts)
is occuring, the trouble may be in ASUL, U2 YES I
or U3,
Check Q1, ASRI,
ete.
Figure 8-27. A9 Power Supply Board Troubleshooting Tree.