Tektronix 2235 User Manual

M
ai
n tena n ce-2235 Service
ages exceedi ng t hose give
n for typical emitter-to-collector

DIOD ES . Α diode can be c
h
ec
ked for eit he r an open or α
values coul d indicate eit
h
e
r α n onsatu rated device operating

s
h orted con dition by meas u
ring t he resista nce betwee n te r-
normally or α defective (o p
en -circuite d ) transistor . If t he de-

mi n als wit h an o h mmeter set to α
range h aving α low inter-
vice is conducti n g,
voltage will b e develo p ed across t he re-

ηαΙ so u rce c
u r r ent, suc h as t h eR
Χ 1 k Ω range . T he d iode
sistors i n series wit h it ;
if it is open, no voltage will be

resista nce s
h
o
u ld b e very h ig h in one
direction and very low
develope d across t he resistors
in series wit h it, unless cur-

w hen t he mete
r leads are r eversed .
rent is b eing sup plied b y α
parallel pat h .
Wh e n con du cting, silicon
d iodes sh ould h ave 0 .6 to 0 .8
V
CA υ τ 10 Ν

across t h eir ju nctio n s, and sc
h ott k y diodes sh oul d h ave 0 .2
to
0 .4 V across t h eir j un ctions .
H ig h er r eadings indicate t
h
at
t hey are eit h er reverse b iase
d or defective, d ependi ng on
Wh e n c h ec k i ng emitter-to-base
j unctio n s, do notuse

polarity .
an
oh mmeter r ange t h at
h
as
eit h er α h ig h inter n al cur-
re n t or voltage . H ί gh
current or h ig h voltage ca nd am-
age

t he

transisto
r .

R everse

b iasing

t he

RE SISTO
RS . C h eck resistors wit
h
an
o h mmeter . R efer
emitter-to-base j unctio n
wit hα h ig h c u rr en t may d e-

to t h e " R
eplacea b le E lectrical parts"
list for t he tolerances of
gr ade t he tra n sistor's cu
rrent-tra n sfe r ratio ( B eta) .

resistors used
in t h is instr u ment .
Α resistor normally does
not require
replacement u nless its
measure d value varies
widely from
its specified value a nd
tolerance .
Α transisto r emitte r -to-base j
unction also can b e checked
for an open or s h orte d
condition by measuring t he resis-
tance b etween terminals wit h an o
h mmeter set to α range

I NDU CTO RS . C
hec k for open i n ductors by c
heck ing con-
h
aving
α low
internal sou rce curre
n
t, suc
h as t he R Χ 1 k Ω

tin u ity wit h an oh
mmete r . S h orted or partially s
h orted i nd uc-
range . T h e jun ction resistance s
h
ould
b e very h ig h i n one

tors can u sually
b e fo und by c hec
k ing t he waveform
direction and very low w hen t h e
meter leads are r eve r se d .

response w h e
n h ig h -fre qu ency signals are p
assed t h roug h
t he circuit .
Wh en tro ub les h ooti n gα field-effect
transistor, t he volt-
age
across its elements can b e c
h
ec
k ed in t he same ma nn e r

CA P ACITO
R
S .
Α lea ky or sh orted capacito
r can b est b e
as
previo u sly descri bed for ot
h
er
transistors . However, re-

detected b y c
heck ing resista n ce wit
h
an
o h mmeter set to
mem b er t h at in t he n ormal d epletio
n mode of operatio n , t he

one of t he
h ig h est ranges . Do not exceed
t h e voltage rating
gate-to-so u rce j unction is reverse
b iased ; i n t h e enhan ced

of t he cap acitor .
T he resistance rea d i ng sh ould be
h ig h after
mode, t he j unction is forward b
iased .

t he cap acitor is c
harged to t he output
voltage of t he oh m-
meter . An op en cap
acito r can be detected
wit h α capaci-
tance meter or b y c
heck ing w h et h er t h e capacitor
passes ac
I NTE GR AT ED CI RCU
ITS
. An
i n tegrated circuit (IC) can

sig n als .
b e checke d wit h α
voltmeter, test oscilloscope, or by d irect
sub stitution . Α good
understanding of circuit o p eration is
essential to tro ub les h ooting α circ
u it h aving an IC . Use care

10 . Rep ai r an
d Ad ju st t h e Circ u it
w hen chec k ing voltages and
waveforms a r oun d t h e IC so
t h at ad j acent leads are
not sh orted toget h er . T he grabb er

If any defective p
arts are locate d , follow
t h
e
replacement
ti p or an IC test cli p provides
α convenie n t mea ns of clipping

p
rocedu res given un
d er "Corrective M ai
n
tena
n ce" in t h is
α test probe to an IC .

section . Afte r any
electrical com pon ent h as b ee
n re p laced,
t he performance
for t h at p articular
circuit s ho u l d be
check ed, as well as
t h e perfo r ma nce of ot
h
er
closely related
CΑυτ 1 Ο Ν

circuits . Since t
h
e
power su pplies affect all circ u its, p
erfo r -
mance of t he entire
instr u ment s h oul d be c hec
k
e
d if wor k
h as b een done in any of
t he p ower sup plies o
r if t he powe r
Wh en c h ec k ing α d iode, d
o n ot use an oh mmeter

tra n sformer h as been re p
laced . R ea dju stme n t of
t he affect-
ra n ge t h at has α h
ig h inte rn al curre n t . H ig h cur rent

e d circ u it r y may b e
n ecessary . R efer to t
h
e "
P erforma nce
can damage t
h
e diode
. C h ec k s on diodes can b e p
er-

Chec k P roce d ure" a
nd "A dj ustme n t P rocedure"
(Sections 4
formed in muc
h t h e same ma nner as on transisto r

and 5) and to
Table 5-1 (A dj ustment Inte r actio
n
s) .
emitter-to- b ase j u n ctions ; u
se α dynamic tester, su c h
as t he T EK T
R
O
N IX 576 Curve Tracer .

Tektronix 2235 Specifications

General

Brand	Tektronix
Model	2235
Category	Test Equipment
Language	English