HP Lab Series - Repair and Adjustment Procedures; Repair and Replacement Guidance

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•
•
Table
S-6.
Preregulator/ContrOl
Circuit
TroublesHooting
STEP
MEASURE
RESPONSE
PROBABLE
CAUSE
1
Wavefonn
between
Taps
4
and
a
af
a.
Normal
firing
pulse.
a.
CR3
5
defective.
R102
T2.
open.
R84,
Ll.
CR28,
CR29,
Tl
defective~
b.
No
firing
pulse.
b.
T2
open.
Proceed
to
Step
2.
2
Waveform
between
TP23
and
TP67.
a.
0
Volts.
a.
Q19
shorted.
Cl
1
shorted.
Ql8
open.
R96, primary
T2
open.
Proceed
to
Step
3.
b.
+16
Volt
level.
b.
Q19
open.
R96
shorted.
Q 18
shorted.
Proceed
to
Step
3.
c.
Waveform
distorted.
c.
Proceed
to
Step
3.
3
Waveform
between
TP23
and
TP66.
a.
Amplitude
incorre~.
a.
C22,
CR16, or
CR17
de-
fective.
R91-R931
R97
R98,
R99
incorrect
val-
ue
or
open.
Proceed
to
Step
5.
b.
Period
incorrect.
b.
CR15
defective.
Pro-
ceed
to
Step
4.
4
Waveform
between
TP23
and
TP65.
a.
Amplitude
incorrect.
a.
CR13,
CR14, CRlS
de-
fective
.
b.
Period
incorrect.
b.
CRlO,
CRll
defective.
5
Waveform
between
TP23
and
TP64.
a.
Amplitude
incorrect.
a.
RlOO.
RlOl,
C23
defeo-
tive.
b.
Period
incorrect.
b.
CR9, CR12
defective.
5-67
REPAIR
AND
REPLACEMENT
5-68
Before
servicing
a
printed
wiring
board,
refer
to
Section
VI ·of
this
manual
which
contain's
a
list
of
replaceable
parts.
Before
replacing
a
semicon-
ductor
device!
refer
to
Table
5-7
which
lists
the
special
characteristics
of
selected
semiconductors.
If
the
device
to
be
replaced
is
not
listed
in
Table
5-:7,
the
standard
manufacturer•
s
part
number
listed
in
Section
VI
is
applicable..
After
replacing
a
semi-
conductor
device,
refer
to
Table
5-8
for
checks
and
.adjustments
that
may
be
necessary.
Table
5-·7..
Seleeted
Semiconductor
Characteristics
REFERENCE
CHARACTERISTICS
~PART
NO.
SUGGESTED
DESIGNATOR
REPLACEMENT
Ql
Matched
differential
amplifier.
NPN
1854-0229
2N2917
G.E.
Si
Planar.
70
(min.)
hFE
ic
=
lmA.
VCE
=
5V.
Ico
O.Olf!A@
Vcbo
=
5V.
Q2
Matched
differential
amplifier• NPN
Si~
1854-0221
2N4045
Union
Carbide
CRl.
CR22-25,
Si.
rectifier,
900mA,
200prv
1901-0327
1N5059
G.E
•
CR32,
CR34
5-13