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Maintenance
—
Type 1A5
the attenuator s
e
ction pass through the holes in the board.
After s
ol
dering these leads to the DISPLAY switch, they
s
ho
uld be pos
i
t
i
oned so that they are ne
hole in the metal chassis.
Transistor locations on the Input Amplifier board are il
lus
tra
ted in Fig. 4-6. (F
i
g. 4-1 illustrates proper placement of
transistors within bases.) The plastic caps must be k
cur
e
ly in place to insure balanced heating and thermal in
sul
a
tion for transistors.
Pl
a
stic caps can be removed by
pulling up on the lower edge of the cover at the flat su
of the transistor mounting base, us
s
i
m
i
i
a
r device. To replace caps, s
Q297 is packed in s
i
licone grease in its heat sink. The
locating tab must be removed from the transis
is put into the he
a
t sink. The heat sink mounting nuts must
be k
e
pt tight. Note that both mounting nuts are ins
from the board by mica washers.
To remove relay K295, the legs of the clamp must be
sprung out and up. The contacts
a cleaning-type lubric
a
nt whenever necess
ins
t
alling the relay, align the locating pin with the hole in the
board. Make certain that the clamp sn
Output Amplifier B
oa
rd. This board does not require
removal for component replacements.
ess
a
ry, observe the following precau
F
i
g. 4-8. H
4-12
a
rly centered in the
e
pt s
e
r
face
i
ng a bent s
o
ldering aid or
i
mply sn
a
p them in place.
to
r before it
ula
ted
sho
uld be cleaned with
a
ry.
When re
a
ps s
e
cur
e
ly in place.
If removal is nec
t
ions:
i
gh F
r
equency Compens
at
ion C
o
Check the wire color code against F
excepti
o
ns.
Note the 4 s
q
u
a
re-pin connectors on the underside of the
board.
P
o
tentiometers can be removed with the board by loosen
ing the s
e
t screws on the front of the couplings and pulling the
shafts forward until they disconnect.
c
o
upling while pulling on the
Component locations are indicated in F
placement of transistors within bases is shown in F
The High
F
req
uency Compensation
[F
i
g. 4-8) can be removed from the Output Amplifier board
by removing one s
cre
ing the board out. Keep it parallel to the Output Amplifier
board during removal and replacement to avoid bending
the s
q
uare pin connectors.
nectors may damage the reed switches.) When replacing it,
insure that all pins engage their sockets. F
High F
re
quency Compensation Component board and iden
tifies components located on it.
R
e
ed switches and coil assemblies can be replaced as
assemblies or as individual components. To replace an as
s
e
mbly, cut all 6 wire leads close to the coil and switch. R
move the ass
e
mbly and uns
from the Output Amplifier board and the two leads from the
m
p
onen
t
board.
(A
tta
ches to Output Amp
i
g. 4-7 and note any
Hold back on the
sha
ft.
i
g. 4-7.
Component board
w from the center of the board and lift
(B
e
nding the s
q
u
a
re pin con
i
g. 4-8 shows the
old
er and remove the 4 leads
li
fier board.)
[P
r
oper
i
g. 4-1.)
e
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