HP 435B - Page 67

M odel 435 Β

Service
8-6 .

RE
CO
MMEN D E DT E ST E Q U I PMEN T

f
r
o m co
m pon e n t m o un t in g ho l es . Sh a r p
Equipment r ecommended in Table 1-2 should be

ob j ects m ayd a m age t h e plate d -t hr ou g h
used for testing and t roubleshooting the P ower

co ndu cto r .
M eter to ensure that i t i s operating within t he
specifications listed in Table 1-1 . T est
equipment

ε .

U se α s uction device or wooden toothpick to
that m eets or e xceeds the critical s pecifications

r
emove solder from component m ounting h oles .
listed may be u sed in place of recommended
e quipment .

d .

After soldering, r emove excess flux from t he
soldered a reas and a pply α protective coating to
prevent contamination a nd corrosion .
8-7 . REP AI R
After repairing any c ircuitry w ithin t he P ower .

8-1 ρ ,
Component R eplacement
M eter, r efer to Section V a nd perform t he
ad j ustments .

The f ollowing procedures are r ecommended when
component r eplacement i s n ecessary :
P erform t he tests in Section IV to
ensure that the

α ,

R emove d efective component from board .
instrument
i s operating within t he specified
limits .

b .

If component was unsoldered, r emove solder
NOTE

from mounting h oles with α s uction device or α
w ooden toothpick .
I f t h
e
Α 3 P owe r R efe r e n ce Asse m b ly i s
repa
ir
e
d ,
see
t h e P owe r R efe r e n ce O u t-

ε .

S hape l eads of replacement component to
pu t test in Sect i o n
I
V fo
r
instructions on

m atch mounting h ole spacing .
sett in g t h e powe
r
o
u tp u t level .
8-8 . G ENER A LS ERV IC E I NF O
RM ATIO N
8-9 .

E tc
h
ed Circuit
B
oards
The etched c
ircuit
b oards
u sed in Hewlett-Packard
e
quipment are the plated-through t ype consisting
of metallic conductors b onded to b oth s ides of an
insulating m aterial . The m etallic conductors are
extended t hrough t he component h oles or inter-
connect h
oles by α
plating process . Soldering can
be p
erformed
on
either s ide of t he board with
e qually good results . T able
8-1
lists r ecommended
tools and materials f or use in repairing etched
c ircuit b oards . F ollowing are r ecommendations
and precautions p ertinent to etched c ircuit r epair
work .
α .

Avoid unnecessary component substitution ;
i t can r esult in damage to the circuit board a nd/or
ad j acent components .
ΝΟΤΕ
A l t h ou g hn ot reco mm e nd e d w h e n bot h
s ides of t h e c ir c ui t boa rd a r e access i b l e,
a xi a l l ea d co m pon en ts s u c h as r es i sto r s
a nd t u b ul a r ca p ac i to r s ca n be rep
l
ace
d
w i t h ou t un so ld e rin g . C li p l ea
d
s n ea r
bo dy o r d efect iv e co m pon e n t, remove
co m po ne n t a nd st r a i
g
h te n
l
ea
d s l eft in
boa rd . W r a p l ead s of rep
l
ace m e n
t
co m
-
pon e n t o n e t urn a r o und o ri
g
ina
l l
ea
d
s .
So ld e r w r appe d co nn ect i on a nd c li p off
e x cess l ea d .
d .

Insert component
l
eads into
m ounting h oles
and position component as
original was p osi-
tioned . D o n ot
f orce l eads into m ounting h oles ;
sharp lead e
nds m ay damage the plated-through
conductor .
8-11
. Operational
A m plifiers
b .

D o n ot u se α high power soldering iron on

The source
of gain in an operational a mplifier can
etched c ircuit b oards . Excessive h eat m ay lift α

b
e
characterized as an ideal, differential voltage
conductor o r damage the board o r α component .

amplifier having l ow output impedance, high ίη -
put impedance, and very high differential gain .
CA U TIO N

The output of
an
operational a mplifier is propor-
tional to the difference in t he v oltages applied to
D o n ot u se α s h a r p m eta l ob j ect s uc h as

t he two input terminals . In u se, the amplifier out-
an awl o
r
tw i st
drill
to remove
so ld
e
r

put drives the input v oltage difference close to z ero
through α f eedback path .
8- 3