Tektronix 2235 User Manual

M ai n te na n ce-2235 Service
Th e h eat-si nk -mounted power su pp ly tra n sistors are i n-
sulated from t he h eat sin k . In addition, α h eat-sin k com-
pound is use d to increase h eat tra n sfer ca pab ilities .
R ei n stall t he i nsu lato r s and replace t he h eat-sin k com pound
w hen replacing t h ese transisto r s . T h e com po un d s h o u l d be
a pp lie d to b ot h sides of t h e insulators an d s ho u l d b e a p plied
to t he b ottom side of t he tra n sistor w h ere it comes i n con-
tact wit h th e insulator .
ΝΟΤΕ
After re p laci n g α p owe r transistor, ch ec k t h at t he col-
lector is n ot s h orted to t he heat si nk befo r e applying
power to t he i n st r ument .
SO L D ER I N G T E C HN IQ UE S
Th e relia b ility a
n
d accuracy of t
h
is instr u me
n
t can be
maintained only if p ro p er sol d
eri
n g tec hn i ques are used to
remove or re p lace p arts . General solderi n g tec hn i q ues,
w h ic h apply to
main
te
n
ance of any
p
recisio
n
electro n ic
e q ui
p
me
n
t, s
h
ould be used
w h
e
n
wo
rk i ng
on t
h
is
i n st r ument .
W
A RN I NG
CA U TIO N
Attem p ts to un sol d er, remove, and
r
esolder leads
f r
om t
h
e
component
side of α circ u
it
board may
cau
se
d amage to t
h
e reverse side of
t h
e ci
r
cuit board .
Th
e
following
tec
h ni q ues sh o u l db e used to re p lace α
component on any of t he circ u it boar d s :
1 . Tou c
h
th e vacuum desoldering tool to
t h
e lea d
at t h e
sol de
r
co
n
nection
. N
eve
r
place
t h e iro n d irectly on t h e
board ;
doing
t
h
is may damage
t h e boar d .
ΝΟΤΕ
Some com
ponen ts a r e d iffic u lt to r emove f r om t h e ci r -
c u it b oar d du e to α ben dp laced In eac h lead d uring
mac h ine i n sertio n of t h e component . T hep ur pose of
t he bent leads is to h old t h e com p onen t i np lace dur-
ing α solder-flow manufacturing process t h at solders
α
//
t
h
e components at once . To ma
k
e
r
emoval of ma-
chine-Inserted components easier,
straig h ten t h
e
component leads on
t h
e reverse side of
t h
e
circuit
board
wit h
α
small
sc
r
ew
d river
or
p lie r
s .
It
may b e
n ecessa r y to r emove t he circuit b oard to gain access
to t he component leads on t he reverse side of t he
ci
r
cuit board . Circuit- b oard removal and
r einstallation
p
roce
du
res
are
d
iscusse d late r i n t h
is
sectio n .
2 . Wh
en
removing α mu lti p i n component, especially
an
To avoid an electric-s h oc kh azar d , ob serve t h
e follow-

IC, do
not h
eat a dj
ace n t p ins consecutively .
Apply
h eat to
ίη gp r ecautio ns b efore attempting any
sol d eri n g : tu r n

pins at alter n ate sides a nd e nds of t
h
e
IC
as solde
r
is
re-
t he i n stru me n t
off, d isconnect
if f r
om t he ac p ower

move d . Allow α moment
for t h
e
circuit
board
to cool b efo r e
so u rce, an
d allow ap p
roximately
t
hr
eeminu tes for t he

procee d to t he
n
ext
pin .
power-sup p ly capacitors to d isc h
arge .
CAUTION
Use rosi n -core wire sol d er containing 63%
ti
n
and 37%
lead . Contact yo ur local Tek tronix F
ield Office or re p resen
tative to ob tain t he n ames of
approved sol d er ty p es .

E xcessive
h
eat ca
n
cause
t h
e etc
h
ed
circ u it con du c-
tors to se p a
r
ate
f r
om
t h
e
circuit
board .
N eve r
allow
t
h
e solde
r extractor ti p to remai n at o ne p lace
on
t he
Wh en solde r ing on circ u it
boards o
r small i n
su lated

board
for
more
t h
a
n t hr
ee
seco nd s . Sol d e r wic k ,
wires, u se
only α 15- to 25-watt, p e
n
cil-ty pe soldering i r o n
.

spr ing-actuated or s q ueeze-bu l b sol d er su c k ers, a nd
Α h ig h er wattage soldering i r
o
n
ca
n
cau se etc hed ci r cu it

h eat bloc k s (for d esol d
eri ng m
u
ltipi n
components)
con d u ctors
to separate
from
t
h
e boar d base material and

must not beused . Damage cau se db y poo
r soldering
melt t he insulatio n
on
small wires . Always k
eep th e sol d er-

tec h ni q uescan voi d t h e
i n
stru ment wa
rr
anty .
i n g-iron tip pro p erly tinned to en sure b est h
eat
t r
a
n
sfe
r f r
om
t he i r o n ti p to t he solder j oi n t . To p rotect h
eat-sensitive
components, eit h er h old t he com po nent
lead
wit h
lo
n g- n
ose

3 . To replace t he com po
n
e
n
t, bend th e leads of
t h
e
r
e-
p liers or place α h eat b loc k b etween t h e
com
p
o
n
e
n
t b ody

placeme
n
t item to
fit t h
e
h oles i n th e circ u it b oa rd . If t he
and t h e sol d er j oint . Apply only e n o ugh solder
to ma
k
e α

component is replaced
w h ile t he b oard is i n stalle d in t he
firm j oint . after solde r i n g, clean t he area a r ound th e
solde
r

i n strument,
cut
t h
e
leads so t hey p rot ru de
only
α small
connection wit h an app r oved flux-removing solve n t (s uch as

amo un t t hrough th e r everse side of t he circ u it board . E xcess
iso p ro p yl alco h ol) and allow it to air d ry .

lea d le n gt h may cause sh orting to ot h er cond u ctive p arts .

Tektronix 2235 Specifications

General

Brand	Tektronix
Model	2235
Category	Test Equipment
Language	English