Tektronix FG 504

REL ATI VE
S U SC EP TI B I L ITY TO
STATIC DISC H A R
G
E DA M
AG E
' V oltage equ ivale n t fo r levels :
1 = 100 to 500 V

4 = 500 V

7 = 400 to 1000 V (est .)
2 =
200 to 500 V

5 = 400 to 600 V

8 = 900 V
3 = 250 V

6 = 600 to 800 V

9= 1200 V
( V oltage d isc ha r ged f r om α 100 pF ca p acito r t hr
o
ugh
α
r
esista n ce
of 100 o h ms .)
Circuit Isolatio n
N
ote t he sym p tom . It ofte n i d entifies t h e circuit i n
w h ic h t h e trouble
is located . Wh en trouble sym p toms
ap pea r in more t h an one circ u it,
c
h
eck t he affecte d
circuits by ma k ing waveform a nd voltage
measureme n ts .
I n correct ope r ati n g of all circuits often m
ea ns tro u ble
i n p ower su pp lies . U sing α multimeter, c heck first for
correct voltages of t he indivi du al regulate d
supplies
according
to t he circuit diagrams and a dju stme n t
pro-
cedures .
T h
e
n
c
h
ec k t he u nregulated supplies of t he
power mo d ules . Defective
com
p
o nen ts elsew here i n t he
i n st r uments can appear as p ower su p p ly p
roblems . In
t
h
ese i n stances, suspected circuits s h
o
u l d
be dis-
co nnecte d from
a pp aren tly bad p owe r sup p lies o ne at α
time to n arrow t he search .
V oltages a nd W avefo r ms
Table 5-1
Ofte n defective com p o n en ts can be
locate d by usi n g
waveform and voltage i n dicatio ns w hen t h ey a pp
ear on
t h e circuit d iagram
or i n t he a dju stme n t p roce d ures . Suc h
waveforms
a nd voltage labels are ty p ical indicatio ns and
will vary betwee n
instrume n ts .
Com
p
onent C h ec k i ng
M ai n te na n ce- F
G
504
(S
N Β
040000 & UP)
If α com po nent cannot be disconnecte d from its circuit,
t he effects of t he
associated circuitry mustbe con si d ered
w hen evaluati ng t he meas u reme n t . E xce p t
for soldered-in
tra n sistors an d i n tegrated ci r cuits,
most compone n ts ca n
be un sol dered an d lifted at o n e end from t he circuit boar d .
T r an sistors and I n tegrate d Circuits (IC) . Tu r n t he
p ower switc
h
off befo r e removing or re p laci n g any
semico nd ucto r . See F ig . 5-1
for semicond u ctor basi ng .
Α goo d c heck of tra n sistor operatio n is actual perfor-
ma nce und er
operati
ng
conditio n s . Α tra n sistor can most
effectively be checked by su b stit u ting
α new com p o n en t
for it (or o ne w h ic h has bee n checked p reviously) .
How-
ever, be sure t h at circuit con d itio ns are n ot suc h t h at α
replacement t r a
n
sistor m ig h t also be damaged . If su b -
stitute tra n
sistors
a r
e not availa b le, u se α dynamic teste r .
Static-ty p e teste r sare n
ot recomme
n
ded since t hey do n ot
c h ec k o p eratio n un der simulated o p erating co n ditions .
An
an tistatic
suction-ty pe desol d eri n g tool ca n be used to
remove sol d ered-in
transistors ; see compo nent replace-
ment proce dure for d etails .
I n tegrated circuits
ca
n
be ch ec ke d wit h α voltmeter,
test oscilloscope,
or by direct su bstit u tio n
.
Α goo d und er-
sta nding of t he circuit d escri p tion is essen tial
to
t
r ouble-
sh ooti ng circ u its co n tai n i n g i n tegrated circuits . O p er-
ati ng
waveforms, logic levels, and ot h er ope r ati n g i n for-
matio n for t h e integrate d
circ
u its
are given i n t he circuit
descri p tio n i nformation . Use care w hen
c
h
eck i n g voltages
and waveforms aro un d t he integ r ate d
circuits so t h at
a dj ace n t lea ds are n ot sh orte d toget h er . Α conve n
ie
n t
means of cli pp i ng α test p robe to t h e 14-a n d 16-pin in-li n
e
i n tegrate d ci r cu its is wit h an i nteg r ated ci r cuit test cli p .
T h
is device also d oubles as an extractio n tool .
R e p lacement semico ndu ctors sh oul dbe of t he o r igi n al
ty pe or α direct re p laceme n t . F igure 5-1 s h ows t he lead
co
n
figuration of t h e semicon d uctors used in t h is i n stru-
me n t system . Wh en r emovi n g
sol d ered -i n transistors, use
an an tistatic suctio n-type de-sol d eri ng
tool to remove t h e
sol d er from t he h oles i n t he circ u it board . See M ai n -
tenance Ai ds .
An extracti n g tool sh oul d be u sed to remove t h
e 14-and
16- p i n integrate d circuits to preven t d amage
to
t h
e pi
n
s .
T h istool isavailablefrom Te k tro n ix, I nc . See M ai n
te
nan
ce
Aids . If an extracti ng tool is n ot available, usecaretoavoid
damagi n g t he p ins . Pull slowly and evenly on both ends of
t he i n tegrate d circuit . Try
to avoi d h aving o ne e nd of t he
i n tegrated circuit d ise n gage from t h
e soc k et befo r e t he
ot h er en d .
Semicon d uctor
Classes
R elative
Susce p tibility
L evels'
M OS or C M OS microcircuits or d iscretes,
or li near microcircuits wit h
M OS i np
uts ( M ost Sensitive) 1
E C L
2
Sc h ott ky sig n al dio d es 3
Sc h ott k y TT L
4
H ig h -fre quen cy bipolar tra n sistors 5
JFE Ts
6
L inear microcircuits 7
L ow- p
owerSc h ott ky TT L 8
TT L ( L
east Se n sitive) 9