Tektronix 7A16A Instruction Manual page 16

M
aintenance-7 Α16Α
Troubleshooting Equipment
4. Check Instru ment Performance .
C
h ec k
t
he cali br a-
tion of the unit or the affected circ uit, by
p
erformi ng
The following e
q
ui pment is useful for troubles h ooting
P
erformance Chec k of Section 5. Th e app arent tro u ble may
t h e 7 Α 16 Α.
only
b
e α resu lt of mis-adj ustment, and may
b
e corrected
by calibration . Co mplete cali bration instructions are give n
in Section 5 .
1 . Semiconductor Tester-Some means of testing the
tra n sistors,
d
io des, and FE T's used in th is inst rument is
helpful . Α
t
ransistor-curve tracer such as the TEK TRON IX
5. Chec k Voltages. Often the
d
efective component or
Ty pe 576 will give the most complete informatio n.
stage can
b e locate d by c hec king for the co rr ect voltage in
the circuit. Typical voltages are give n on the
d
iagrams;
howeve r, th ese are not absolute and m ay vary slig h tly
2. DC Voltmeter and Ohm meter- Α voltmeter is re-
b
etween instruments . To obtain op erating con
d
itions
quire
d
for chec k ing voltages within the circuits, an
d
an similar to those used to ta ke these read ings, see t h e
ohmmeter for chec king resistors an
d d
io
d
es . instructions in the Diagram section.
3. Test Oscillosco p e-Α test oscillosco pe is re
q
u ired to 6 . C h ec k In
d
ivi
d
ual Components. The following
view waveforms at different points in t h e ci r cuit . Α meth o
d
s are provided for chec king the in
d
ivi
d
ual com-
TEKTRO
N
IX 7000-series Oscilloscope e
q
uippe
d
with α
p
onents . Comp o nen ts w hic h are sol
d
ere
d
in place are
b
est
readout system, 7D13 Digital Multimeter unit, 713-series ch ec ked by disconnecting one en
d
to isolate the meas ure
Time-Base unit, an
d
α 7A-series Amplifie r unit with α 10 Χ ment from t h e effects of su rr oun
d
ing circuitry .
probe will meet the
n
ee
d
s of
b
oth items 2 an d 3.
NOTE
4.
P
lug-in Exte nd er-Α fixt ure t h at p
ermits operation of
t he unit o u tside of the
p
l ug-in comp artment for b etter
To locate intermittent or tempe
r
at
ur
e sensitive com-
accessibility du ring troub leshooting . Order TEK T R ON IX
ponents mounted on t
h
e atten
u
ato
r b
oa
rd,
Q uί
k
P
art Number 067-0589-00.
Freeze (Miller Step
h
enson, MS-240, T
EK
T
R
O
N
IX
P art N um b
er 006-0173-01) is
r
ecommen
d
ed. Dry ice
or
d
ί chlordί -fluo r
remet
h
ane (
Fr
eon 12, Du
p
ont o
r
Can- Ο -Gas) may also b e use d
. Ot
h
er types of circuit
Troubleshooting Procedure
coolant may
d
amage t
h
e poly ph
enylene oxi
d
e boa
r
ds.
T
his troub leshooti ng procedure is arra nge d in an or der
whic h
c
h ec ks the simple trou ble
p
ossi bilities
b
efore
p
ro-
Α . T
R A
N
SISTOR S. The best ch eck of transistor ope r a-
cee
d
ing with extensive troub leshooting .
tio n is actual
p
erformance un
d
er o
p
erati ng co nd itio ns . If α
tra n sistor is suspecte
d
of being
d
efective, it can best be
checke
d
by substituting α compone nt kn ow n to
b
e goo
d
;
1 . Chec k Control Settings . An incorrect setti ng of the
however, be s ur e t h at circuit co nd itions are not such t
h
at α
7Α16 Α controls can in
d
icate α trouble that does not exist.
re p lacement might also
b e
d
amaged. If substitute transistors
If th ere is any
q
uestion about the correct function or
are not availa ble, use α
dynamic tester (suc h as
operatio n of α co ntrol or front-pa nel connecto r , see the
TEK TRONIX Type 576) . Static-ty
p
e testers may b
e
u
sed,
Operating I nstructions sectio n.
but si nce they do not ch ec k operation under si mulate
d
o
p
erating con
d
itions, some
d
efects may go u
nnoticed . Be
sure the powe r is off
b
efore attempting to remove or re
p
lace
2. Chec k Associated Eq ui pment . Before procee
d
ing
any transistor .
with
trou blesh ooti ng of t h e 7 Α 16 Α chec k
t
hat the
equi pme n t use d with
t
his instrument is ope rating co rrectly .
If
p
ossible, substitute an am plifier
u
nit kn ow n to
b
e
Β. DIOD ES. Α
d
iode can be chec ke
d
for an open o
r
operating correctly into the indicator un it an d see if the
shorted co nd itio n by meas uri ng the resistance betwee n
problem
p
ersists. Chec k
t
hat the input signals are pro
p
erly terminals . With an ohm m eter scale
h
aving an internal source
connecte d
a
nd
t
h at the interconnecti ng ca bles are not of
b
etween 800 millivolts and 3 volts, the resistance should
d efective .
be ve ry
h
ig h in o ne direction and very low when
t
he leads
are reversed .
3.
V
isual Chec k. Visually chec k
t
he
p
ortion of t h e
instrument in whic h
t
he trouble is sus
p
ected. Many trou bles
ca n be locate d by visual indications, such as unsol dered
con nections,
b
ro ken wi res,
d
amaged circuit
b
oar
d
s,
Do not
u
se αη o
h
mmete
r
scale t
h
at
h
as α high internal
damaged components, etc.
c
urr
ent . High c u
r
r
ents may damage t
h
e diodes.
42