Tektronix 2235 - F Ilter Circuit B Oard; Alt Sweep Circuit B Oard

1 . R emove
t he P ower-Su pp ly sh ield (see t
h
e "
P owe r -
Sup p
ly
S
h iel d " removal p r oce du re) .
2 . R emove
t he five wires to t he F ilte r circ u it boar
dby
unsoldering
two wires from t h e M ain circ u it b oard,
two fr om
t he li
n
e
filter, and one wire from t he f u se
h
olde
r
(pull
the
protective
cap com p letely off t he f use
h
older
b efore
un
solderi n g) .
3 . R emove
two screws securi n g t he F ilter ci
r
cuit
b oa r d
to t he bac
k
of
t he ch assis frame . L ift t he F ilter ci
r
cuit
b oard
out of t
h
e
instrument .
To reinstall
t he F ilter circ u it b oard , p erform t h e
following
ste p s .
4 .
R einstall two screws securing t he
F ilter circ u it board
to t he b ac
k of t he c h assis frame (removed in ste p 3) .
5 . R esol d er
t h e five wires f r om t he F ilter circ u it b oa
r
d
to
t h e M ain
circuit b oard, line filter, an d fuse h ol d er (unsol
d ered
i n ste p
2) .
6 . R ei
n
stall
t he P ower-Su p ply sh ield (see t he "
P ower-
Supply S
h
ield"
reinstallatio n procedu re) .
Alt Swee p
Circ u it B oard
To remove
t h e Alt Sweep circ u it boar d , p erform t he
fol-
lowing steps :
4 . R einstall t he Alt Swee p circuit b oard into t he p
lastic
h older attac
h
ed
to t he P ower-Sup p ly sh ield .
Atte n uato r Circ
u
it
B oa rd
M ai ntenan ce-2235 Service
To remove t
h
e
Attenuator circuit b oard, p
erform t he fol-
lowing ste ps :
1 . U se α
1/16-i nch H ex- k ey wrenc h to loosen t he set
screws on bot h t
h
e
C H 1 and t he C H 2 VO LTS/DI V
V
ariable
k nobs and remove
t h
e
knobs .
2 . Set t he C
H 1 and t he C H 2 V O L TS/DI V
switc h
es
to
t he same p osition
. N ote switc h positio n s for rei n stallatio
n
reference ; t hen remove
t h e k nobs b y pulli ng t h em st
r aig h t
out from t he fro n t p anel
.
3 . P lace t
h
e
instrument on its si de an d remove
two
screws securing
t he Atten u ato r board to t h e subpan el (lo-
cated u nder n eat
h t h
e
C H 1 and C H 2 i npu t con n ectors) .
4 . U nsol d er t
h
e
r esisto r s from t he C H 1 and C
H 2 i npu t
connectors .
5 . R emove t he followi
n g
co
nn ectors from t he Atten uato
r
circ u it board, noting
t h eir locatio ns for r einstallation
refere nce :
α . Ρ 9103, α
four-wire connector located beh i n d t he C
H 1
V O LTS/DI
V switc h assem b ly .
b .
Ρ 9108, α four-wire con nector located beh ind t he C
H 2
V O L TS/DI V switc h assem b ly .
c .
Ρ 9091, α t h ree-wi r e connector located b etween t he
C h annel 1 a nd C h an n el 2V ariable p ote n tiometers at
t
h
e rear
of t he Atten u ator circuit boar d .
1 . U se α vacu
u m-desolderi ng tool to unsolder t
h
e
27
p i n s (between
t h
e
Alt Swee p ci r cuit board and t he M
ain cir
cuit board)
from t he M ai n ci r cuit boar d .

6 .
R emove four screws securing t he Top s h iel d to b ot
h
t
h
e
Attenuator circuit b oa r d and t h e b ottom sh iel d .
2 . R emove t
h
e
Alt Sweep circuit boar d fr om t he i
n
st
r
u-
ment b y u
nclippi ng it from t h e plastic h older attac
h
ed
to t he

7 . R emove two screws and t h e groun d stra p from t
h
e
P ower-Sup p
ly s h ield .

rear
of t h e Atten u ator circuit board .
To rei n stall
t he Alt Sweep circ u it b oard, p erform t he fol-

8 . Pull t
h
e
Atte nu ator board straig h t bac k f r om t he front
lowing steps :

of t he i
n
strument
un til t he circ u it board interco nn ecting p i ns
3 . Insert t
h
e
27 p i ns of t he Alt Sweep circ u it b oard
into

are disengage d
and t he switc h sh afts a r e clear of b ot h t h e
Fr ont- P anel circuit boa rd and t he two AC-G N D-DC switc
h
t he M ai
n
ci
r
cuit
board .

s
h afts (located b etwee n t he fro n t- pan el and t he su b panel
.
To reinstall t h e Attenuator circuit b oard, p
erform t he fol-
lowing ste p s :
9 . Insert t h e two
V
O
LTS/DI V switc h s h afts and t he AC-
5 .
R
esol
d er t he 27 p ins to t he M ain circuit board (
u nsol-

G N D-DC switc
h
s
h
afts
into t he front panel h oles . E nsu re
d ered
i n step 1) .

t h at t h e interconnecti ng p i
n
s are
aligned wit h t he Front-Pan-
6- 1 5