Tektronix FG 504

Dio d es . Do n ot use an oh mmeter
t h at h as α h ig h
i n ternal cu rrent
. H ig h currents may da m age t h e d iode, so
use
t he R X1000 scale on t he o h mmeter .
Ordinary sig n al diodes
may be checked for an op en o r
sh orte
d
co
nd ition by measuring t he resista n ce b etwee
n
termi n als . W it h t h e oh mmeter set to t he R X1000 scale,
t he
resistance s h oul d be very h ig
h
i n one
d irection a nd very
low w hen t
h
e lea
ds are reversed .
R esistors . C heck resistors wit h an o h mmeter
. R esistor
tolerances are given in t he R eplaceable
E lectrical P arts
list . R esistors d o n ot normally
n eed to be re p laced u n less
t h e measure
d val u e varies widelyfrom t he specifie d value .
Ca p acito r s . Α lea k y or s
h orte d capacitor can be
d etecte d by c
h
ec
k i n g resistance wit h an oh mmeter on t he
h ig h est scale . Use an o h mmeter w h ic h will n ot exceed
t h
e
voltage rating of t he capacitor . T h e resistance
reading
should be h ig h after i n itial ch arge of t he ca p acitor
.
An
o pen ca p acitor can best be detecte
d wit h α capacitor
tester, or by chec
king w h et h er it p asses ac sig n als .
Cam Switc h es . R epair of cam-ty pe
switc hes s hould be
un derta ken only by
experie n ced mainte n ance p erson n el .
Switc
h alig n ment and s p ri n g te n sion of t he co n tacts m u st
b e
carefully mai n tai n ed for pro p er o p eration of t he switc h .
F or assistance, con tact your local Te k tronix
F iel d Office
or re p resentative .
REV
ΑA PR 1980
NO
ΤΕ
Α cam-type switc h r epair k it including necessary
tools, instructio n s, and r ep lacement
contacts is
available f r om Te k
tronix,
Inc . See
M aintena nce
Aids .
The cam-ty pe switches co n sist of
rotati ng ca m d r u ms,
w h ic h are t u r ned by fro n t-panel kn obs,
and sets of spri n g-
leaf contacts mou n ted on
a dj ace n t circuit boards . T h e
co n tacts are actuated by lobes on
t he cams . T h ese
switc hes can b e disassem
b le d fo r i nspection , cleani n g,
re p
air,
or
re p laceme n t as follows :
1 . R emove screws from t h e switc
h cover and remove
t h e cover . T he
switc h is
now
op en for ins p ectio n or
cleaning
.
2 . To completely remove α
switc h from t he circ u it
boar d , first remove any
kn obs or s h aft extensio ns . L oose n
t h e cou p
ling
at
t h e potentiometer at t h e rear of t he switc
h ,
and
pull
t h e long sh aft out of t he switc h assem
b ly .
M ai n tenance- F G 504 (S
NΒ 040000 & UP)
3 . R emove t
h
e screws
(from t h e opposite side of t
h
e
circuit
board) w h ic h h old t he cam d rum to t he boar
d .
4 . To remove t he cam drum
from t he fro n t support
bloc k , remove t he retaining
ri ng from t h e sh aft on t h efro n t
of t he switc h and slide
t he cam d rum out of t he s up port
bloc k . Be
careful n ot to lose t he small detent roller
.
5 . To re p lace defective
switc h co n tacts, follow t he
instructions
give n in t he switc h repair k it .
6 . To re-i n stall t he switc
h assembly, reverse t he a b ove
procedure .
Incand esce n t B ul b s .
M ost of t h ese lig h t b ul b s are
mou n te d on
t h e sub-pa n el using p lastic sleeve stand-off
s .
U
nsolde r t h e lead wires a nd pull t
h
e bul
b out of t h e sleeve
from t he rear of t h e sub- p anel
.
Circuit B oar d R emoval
NO ΤΕ
Tag or note t h e locations
of αΙ 1 lea d s and plugs for
reassembly refere
n
ce
.
To remove t he M ai n board (rig h t si
d e board ), remove
t h e six screws h oldi ng t
h
e bac
k panel to t h e instrumen t
frame . R emove t h e b ac
k p an
el
. R emove t he S WEEP
DUR ATIO
N , R IS E and F A LL TIME and ATTENUATOR
(dB) k nobs . Disco nn ect all ca b le p lugs co
nnecte d to t h e
b oard . R emove t he fo u r screws
attac h i n g t he board to t he
p lug-i n frame a nd
remove t h e board b y sli d ing t h e b oa r d
bac k war ds
until t he switc h sh afts clear t he fro n t p a
n
el
h oles .
To remove t h eF
unction b oard (ce n te r board ), first
remove all cable plugs
attac h edtothe b oard . T hen r emove
t he fo
u r screws attac h ing t he board to t h e spacers
. Slide
t he b oard to t h e rear of t he i n strume
n t until t he p us h but-
tons clear t h e fro
n t p anel and remove t he board .
To remove
t he L oo p board (left sideboard),d isco
nn ect
cable con n ections to the b oa r d . R emovet
he MUL TI PL I ER
k nob . Un sol d er t hewire from the AM
I NPU T con necto r on
t he fro n t
panel
to
t h e boa rd . N ext remove t he fo u r screws
attac h i ng t
h
e
L oop board to t he ρΙ υ g-i n frame a nd sli det
h
e
boar d to t h e rear of t h e plug-i n u n it u n til
t h
e
H O L D p ush -
button clears t he fro n t pan el .
R
emove
t h e boa rd from t h e
plug-in .
To r emove
t he F loati n g I n terface boar d , first remove
t h e six retaini ng screws on t h e bac k pa
n
el
. R emove t h e
5-5