Tektronix 7A16A Instruction Manual page 18

M
ai ntenance- 7Α16 Α
2. Apply heat from the sol
d
ering iron to th e junction
R
eplaceme nt semico n
d
uctors s h oul
d
b
e of t he original
between the component an
d
t
h e circuit
b
oa rd. type or α direct re
p
laceme n t. Th e sc h ematic diagram shows
t h e lea
d
co nfigurations of the semico n
d
uctors use
d
in th is
instr u ment . If t he replacement semico nductor is not of the
3. Heat-sh u nt t he lea d to the com
p
onent by means of α
original ty
p
e, chec k
t
h e manu fact urer's
b
asi ng
d
iagram for
p air of long-nose pliers .
p ro
p
er
b
asing .
4 . Avoid excessive heating of th e ju nction with
t
he
Circuit
B
oar
d
R
emoval
circuit
b
oard, as this coul
d
se
p
arate the circuit boar
d
wiring
In general, the circ uit boards used in t h e 7 Α 16 Α
n
ee d
from the
b
ase material .
never
b
e remove
d
unless th ey must be re
p
lace
d
. E
lectrical
connections to the
b
oards are mad e
b
y sol
d
ere
d
con
5.
U se electronic gra
d
e 60-40 tin lea
d
sol
d
er .
nections . If it is necessary to re p lace α circuit b oar
d
assembly, use the following
p roced ures .
6. Clip off any excess lea
d
length exten
d
ing beyon
d
t
he
circuit boar
d
. Clea n off any
r
esidual flux with α flux-
removing solvent.
M
etal Terminals. Wh en sol
d
ering metal terminals (po-
tentiometers, etc.) use 60-40 ti n-lea
d
sol
d
er an
d
α 15 to 50
watt sol d
ering iron . Observe the following precautions
when sol dering metal terminals :
1 . Apply only enough heat to ma k e the sol
d
er flow
freely .
2. Apply only enough sol
d
er to form α soli
d
con-
nection .
E
xcess solder may im
p
air the function of t he
p
art .
3. If α wire exten
d
s beyon
d
t
he sol
d
er
j
oint, clip off the
excess .
4. Clean the fl ux from the solder
j oint with α flux-
removing solvent.
Com
p
onent
R
e
p
lacement
WARNING
Α. RE ADOUT CI R CUIT BOARD REMOVA L
1 . Disconnect t he wires connecte
d
to th e outside of the
b
oard .
2. R
emove t he seven screws
h
ol
d
ing th e boar
d
to the
mo u nting s urface.
3. Disconnect th e wires connected to the i nsi de of the
boar
d
.
4.
R
emove the boar
d
from t h e unit .
5. To re
p
lace the
b
oar
d
, reverse the or
d
er of removal .
Β. ATTE
N
UATOR CI RCU IT
B
OA R D REM OVAL
1 . R
emove t he reado ut
b
oar
d
as outlined in the
p
revious proce
d
ure.
2. Disconnect th e in ductor, ca
p
acitor, an
d
two groun
d
stra
p
s connecte
d
to the rear of the
b
oard.
3 ..
L
oosen the front set screw on t he VAR IA BLE
control shaft cou
p
ling (use α 0.050-inch hex-key wrench ) .
Disconnect the equipment from the power source
before replacing components.
4.
R
emove th e re d VAR IA BLE control
k
nob and glass
rod from th e co ntrol sh aft.
Semicon
d
u ctor
R
eplaceme nt. Transistors sh oul
d
not be
re
p
lace
d
unless actually defective. If removed from their
5.
R
emove the remaining front- p anel k nobs using α
sockets
d
uring routine maintenance, return them to their
1/16-inch
h ex-key wrenc h .
original sockets.
U
nnecessary re
p
lacement of transistors
may effect the cali br ation of this instrument. Wh en
transistors are replaced, ch ec k
t
he pe rfo rmance of t he
p
art 6. R
emove th e front
p
anel from the instrument by
of the instrument whic h may
b
e affected.
p ryi ng at center bottom with screwdriver .