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Section V
Paragraphs
i.
Establish an output reference on the
cillator using the OUTPUT MONITOR E X ‑
PAND
switch and REF SET controls.
j.
Increase oscillator. frequency to
adjust oscillator amplitude to maintain
reference.
(0.3
V 1 M C ) f o r a 0.3 V indication
k.
AdjustC2
o n the M o d e l 403A.
test
setup shown in F i g u r e
m. Connect
OSCILLATOR MONITOR
AC VOLTMETER
hp 400E
4 0 3 A - B - 11 0 3
5-11.
F i g u r e
30 V Range
n .
Model 403A RANGE t o 3 0 V. Set o s c i l ‑
Set
l a t o r frequency to
amplitudefor a r e a d i n g of 10 V or
the oscillator m o n i t o r.
(30
V 200 KC) f o r a
p. Adjust C4
reading the same as the oscillator monitor
reading.
5 - 3 1 . T R O U B L E S H O O T I N G .
5-32.
T h i s section contains information designed to
assist in isolating malfunctions in the Model 403A.
Troubleshooting should be undertaken only after it
been definitely established
has
be eliminated by performing the adjustment and c a l i ‑
bration procedure (Paragraph 5-19).
5-33.
Conduct a visual check of the Model
possible burned or loose components, loose c o n n e c ‑
tions, or other obvious conditions which m i g h t suggest
a source of trouble.
5-34. Weak batteries can cause
operation. Before troubleshooting, a new
t e r i e s should be installed.
5-35. Table 5-3 containsa
function symptoms and t h e i r possible causes.
table canbe used t o selecta s t a r t i n g p o i n t f o r t r o u b l e ‑
shooting operations.
5-6
_
test
o s ‑
R e ‑
1 m c .
set
5-11.
200
kc Adjustment
200 k c .
oscillator
Adjust
greater on
Model 403A
cannot
t h a t the trouble
403A
f o r
e r r a t i c instrument
set
of b a t ‑
of several
summary
m a l ‑
T h i s
~
o * .
5-3.
Ta b l e
Troubleshooting
No response to input
B a t t e r y Te s t reads
low
Noisy
indication on
known quiet source
M e t e r pegs when
s w i t c h i n g r a n g e s s w i t c h
M e t e r pulsates when
measuring inputs
less than 15 cps
M e t e r calibration o ff | B a d r e s i s t o r in range
on ranges
t h a t a r e
multiples of 100
apart
R44 (METER
C A L
10 MV RANGE)
w i l l not
adjust
resistance out
Input
of spec
M e t e r does
not track
p r o p e r l y :
a . M e t e r reads con- | R32 b a d
s i s t e n t l y above o r
below a l l meter
divisions
M e t e r reads above | CR3,
some b u t below
other divisions
5 - 3 6 . REPAIR.
5-37. CABINET
REMOVAL.
a.
Remove the f o u r screws at the r e a r of the
cabinet.
b .
C a r e f u l l y slide the Model 403A f o r w a r d ,
of the cabinet.
A LWAY S REMOVE BATTERIES
BEFORE REPLACING ANY PARTS.
A LW AY S T U R N MODEL 403A O F F
B E F O R E REMOVINGBATTERIES.
M o d e l 403A
Fuse F1 blown
Batteries dead
CR1 or CR2 shorted
contacts in
Open
range
switch
Weak batteries
One or m o r e batteries
installed backwards
(R47)
B a t t e r y Te s t C a l
not set
p r o p e r l y
contacts
D i r t y b a t t e r y
CR1 or CR2
noisy
Noisy transistors
(usually Q1 or Q2)
contacts on
D i r t y
range
C10 or C15 leaky
C21, C22, C25,
C26
C31
or C32 open or
leaky
s w i t c h
contacts in
D i r t y
range
switch
Weak batteries
CR4 bad
CR3,
Q1 or Q2
b a d
CR4
b a d
M e t e r b a d
out
00125-4
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