Tektronix 576 - Page 71

2 . C h ec k Instrument Calib r ation . C h ec k t he calib r ation
of t h is instrument orof t h e affecte d circ u it if t he trouble is
k now n to exist in one p artic u lar circuit . T he a pp are n t
trouble may be only α result of misa d j ustment and may be
correcte d by calibration .
Com
p
lete calib
r
ation i n structio n s
are given in t he P erforma nce
C
heck an d Calibratio n section
of t h is manual .
3 . L ocati ng M alf un ctio n i n g Ci r cu its .
To
locate the
source of α malfunction i n inst r ument o p eration, the
t r ou ble sym p tom will ofte n i n dicate t he identity of t he
fa u lty circuit(s) . F or exam p le, if α d is p lay of t he Collector
Su pp ly out p ut ca n be obtai n
e
d on t h
e
test oscillosco p
e
CRT but α d is p lay of t h e Ste
p
Generato r outp ut cannot b e
obtaine d , t h e Ste
p
Generator is probably malfunctioning .
If t he trouble
symptom d oes n ot
i n
dicate
w h
ic
h cir-
cuits) is causing p roblems (for exam p le if t he r e we r e no
Collector Su pp ly or Ste p Generator ou t p uts), α more sys-
tematic trou b les h ooting p roce d ure is necessa r y . F ig . 4-3
p rovi d es α ge n eral g u i de for locating t he p robable ci r cuits
w h ic h are causi ng t h e instrume n t to malf u nction .
T he followi ng p reliminary
p rocedure ensu
r
es
t
h at
t
h e
instrument malfunction
is not cause d by imp ro p er co n trol
settings and h elps d etermi ne
w
h ere
to begi
n
on t he trouble-
s h ooti n g c h art :
Α
. Set t he followi ng Ty pe
GR ATIC ULE I LLUM
RE ADO U TI LLUM
I NT EN SITY
F OC U S
VER TICA L
DIS PL AY O FF SE T Selector
C EN T ERL I NE VA LUE
H O R IZO N TA L
P
OSITIO
N ( V ert an d H o r iz)
F
I NE
P
OSITIO N ( V ert and H oriz)
Z
ER O
CA L
DIS PL AY I NVER T
MAX PEAK V
O
L TS
PEAK P O WER W ATTS
V A R IA BLE
CO
LLE CTO R
S
UPPL Y
POLARITY
M
OD
E
L OO P I N G COMPEN SATIO N
NUMBER O F STEP S
C
URREN T L I M IT
A MPL IT U D E
O
FF S E T
O
FF S E T MUL T
ST
EP
S
PUL S E D ST
EP
S
ST EP F A M I L Y
R AT E
P O L A R ITY I NVER T
ST EP MUL T .1 Χ
576
controls to :
F ully Cloc k wise
F ully Cloc kwise
Trace V isible
Centere d
1 mA
N O RM (O FF)
0
2 V
CO
LLE CTO R
Centere
d
Ce n tere d
R eleased
R
eleased
R elease d
15
0 .5
F ully Cloc k wise
+(
ΝΡΝ )
N O RM
As Is
10
20 mA
2V
Z ER O
0
P resse d
R elease d
REP
N
O
RM
R eleased
R elease d
M
aintenance-Ty p
e 576
Terminal Selecto r

B AS E T ERM ST EP
G EN (N O RM)
LEF T-O FF-R IG H T R
IG H T
Β . Turn on t h e Ty pe 576 an d allow α few minutes to
warm up .
C . C HE CK F O R -Dis p lay of Collector Sup p ly swee p of
about 15 volts
p ea k
on Ty
p
e 576 CRT .
D . If no display can be obtaine d , connect t he 10 Χ
probe between t he test oscilloscope and t he collecto r te r m-
inal on t he rig h t h an d side of t he Standard Test F ixture
(connect grou nd lea d to emitter terminal) .
Ε . C HE CKF O R -Dis p lay of Collector Su pp ly output is
α p ositive-goi ng f u ll-wave rectifie d sine wave of abo u t 15
volts p ea k on test oscillosco p e CR T .
F . Con n ect t he p ro b e to t he rig h t base terminal of t he
Stan d ar d Test F ixtu
r
e .
G . C HE CK F O R -Dis p lay of Ste p Generato r out p ut of
p ositive-goi ng ste p s of 2 volts/ste p on test oscillosco p e
C
R T .
Η . Start with t h e following ste p on F ig . 4-3 accor d ing to
t he r es u lts of t he p revious c h ec k s :
1 . Ste p (A)-No Collector Su pp ly outp ut ; Step Ge n -
e r ator output o r d is p lay on t he Ty pe 576 C R T .
2 . Step (B)-No Collector Supp ly outp ut or i n correct
ou t pu t, b u t Step Generator is d is p laye d an d t h e s p ot can
be seen on t he Ty pe 576 CRT .
3 . Step (C)- Νο Step Generator output (or i n correct
out
p u t), but Collecto r
S
upp
ly is dis p laye d on t he Ty pe
576 CRT .
4 . Step (D)-
Νο d
is p
lay on ty p e 576 CRT (or incor-
rect d is p lay), but Collecto r Supp ly outp u t
and Ste
p
Gen-
erator outp ut are d isplaye d p ro p erly
on
t he test oscillo-
sco p e CR T .
After t he d efective circuit h
as
been locate
d , p
rocee d
wit h ste
p
s 4 t hr oug h 8 to locate an d re p air t he faulty com-
p onents .
4 . V is u al C h ec k . V isually ch ec k t h e p ortion of t he in-
strument in w h ich t h e tro u ble is locate d .
Many
tro u bles can
be located by vis u al in d ications such as un sol d ere d connec-
tions, broken wires, d amage d circ u it boar d s, d amage d com-
p onents, etc .
5 . C hec k Ci r cuit B oa r d Interco n nections . After t he
t r ouble h as been isolated to α partic u lar circuit, c h ec k t he
p in connectors on t he circ u it board for cor r ect con nection .
F igs . 4-5 t h roug h 4-26 s h ow t h e co r rect connections of
eac h boa r d .
T h e p in connectors used in t h is i nstrumen t also pr ovi d e
α convenient means of circuit isolation . For exam p le, if t h e
4-5