Tektronix 454A - Page 110

M ai nt enance- 454zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA ‘ / R 454A
3 . R emove t h e s h i el d f r om t h e cast at t en u at or h ousi ng .

T h e C R T s h i el d s h oul d al so
b
e
h
andl e
d car ef u l l y .
T
h i s
s h i el d p r ot ect s t
h
e C
R T d i s p l ay f r om di st or t i on d ue t o mag-
net i c
i nt er f er ence . I f t h e s h i el d i s d r o pp ed or st r uc k
4 . R emove t
h e
t wo
6- 32 k e p s nut s t h at r et ai n t h e cast

s h ar p l y, i t may l ose i t s s h i el di ng a b i l i t y .
at t en u at or h
ousi ng
t o
t h e i nst r ument f r ont cast i ng .
T h e f ol l owi ng p r ocedur e o u t l i nes t h e r emoval and r e-
5 . U n p l ug t h e d el ay l i ne co n nect i ons f r om t h e
V er t i cal

p l acement of t h e cat h o d e- r ay t ube :
P r am p ci r c u i t b oar d . N ot e t h e or
d
er
of r emoval f or r econ-
nect i on .
6 . R emove t h e t wo scr ews at t h e r ear
of t h
e
ci r c u i t
b oar d .
7 . R emove t h e t wo 4- 40 h ex nut s an d t h ei r f l at was h er s
( a d j acent t o t h e V er t i cal M OD E / T R I GG ER swi t c h s h af t )
t h at secur e t h e V er t i cal P r eam p ci r cui t boar d t o t h e i nst r u -
ment c h assi s .
8 . L i f t
up on
t h e r ear of t h e assembl y an d sl i d e i t out of
t h e i nst r ument . T h e t o p si d e of t h e b oar d an d t h e at t en-
uat or s can now be r eac h e d f or t r ou b l es h oot i ng or par t s
r epl acement .
9 . T h e boar d can now be r emove
d f r om t h e V er t i cal
P r eam p u ni t
as f ol l ows :
4- 1
2
± . Di sconnect al l p i n connect or s .
b . U nsol d er al l connect i ons
b
et ween t
h e ci r cui t boar d
an
d t h
e at t enuat or s an d b et wee n
t h
e ci r cui t boar d
and
t h e V er t i cal M OD E / T R I GG ER swi t c h .
c . R emove t h e r emai ni ng scr ew t
h
at
h ol d s t h
e
V er t i -
cal M
OD
E / T R I GG ER swi t c h t o t h e ci r cui t boar d .
d . R emove t h e f our scr ews t h at h ol d t h e boar d t o t h e
at t en u at or s .
10 . To r e p l ace t h e uni t , r ever se t h e or der of r emoval .
Cor r ect l ocat i on of t h e pi n connect or s i s s h own i n F i gs . 8- 1
t
h
r oug
h
8- 16 .
1 . R emove t h
e
t o p
and b ot t om cover s an d r ear p anel ( or
r ear cast i ng)
as d escr i be d p r evi ousl y .
2 . R emove t h e l i g h t f i l t er
f r om t h e f r ont of t h e C R T .
3 . Di sconnect t h e C R T
ano d e connect or . Gr oun d t h i s
l ea d an d t h e ano
d
e
connect i on t o d i sc h ar ge any st or ed
c
h
ar ge .
4 . Di sco nn ect t h e t wo gr o u nd b r ai ds f r om bet ween t h e
C R T s h i el d an d t h e
V
er t i cal Am p l i f i er c h assi s . E i t h er
unsol
d
er t h e
b
r ai
d
or r emove t
h
e secur i ng nut s f r om t h e
sol d er l u gs .
5 . R emove t h e t wo nut s ( b y t h e gr at i c u l e l i g h t s) w h i c h
h ol d t h e f r ont of t h e C R T s h i el d t o t h e f r ont cast i ng .
6 . R emove t h e gr at i cul e l i g h t s f r om t h e st uds an d p osi -
t i on t h em away f r om t h e s h i el d .
7 . R emove al l d ef l ect i on l eads f r om t h e nec k of t h e
C R T . B e car ef u l not t o ben d t h e p i n connect or s . R emoval
of t h e V er t i cal def l ect i on l ea d s can be f aci l i t at ed b y r emov-
i ng t h e t wo secur i ng scr ews and l ower i ng t h e V er t i cal
Am p
l i f i er c h
assi s .
8 . R emove t h e C R T soc k et .
9 . U nsol d er t h e y- axi s r ot at i on l ea d s at t h e ¥ Axi s Al i gn
cont r ol ( on t h e r ear s u b p anel ) and t h e t r ace r ot at i on l ea d s
w
h
er e
t h ey connect t o t h e t r ace r ot at i on coi l i n t h e C R T
s h i el d .
Cat h o d e- R ay Tube R e p l acement . U se car e w h e n
h an d l i ng ± CR
T .
P
r ot ect i ve cl ot h i ng and saf et y gl asses

10 . R emove t h e smal l b l oc k of f oam l ocat e d bet ween
s h o u l d b e wor n
.
Avoi d
st r i
k i ng
i t on any
o
bj ect w h i c h

t h
e
C R T s h i el d an d t h e DELAY- TI ME MUL TI PL I ER
mi g h t cause i t t o cr ac k or i mp l o d e . Wh en st or i
n g
±
CR T,

p ot ent i omet er .
p l ace i t f ace down on ± smoot h s u r f ace wi t h ± p r ot ect i ve
cover or sof t mat un d er t h e f ace p l at e t o p r ot ect i t f r om
scr at c h es . Do not b en d t h e d ef l ect i o n - p l at e p i ns . I f
t
h
e p i ns

11 . L oosen t h e t wo h ex- h ea d scr ews i nsi d e t h e r ear of
ar e b ent , t h e gl ass seal ar o u n d t h e p i ns may be cr ac k ed ,

t h e C R T s h i el d .
R emove t h e s h i el d angl e cl am p s an d
al l owi ng t h e C R T t o l ose i t s vac uu m .

mount i ng scr ews
.