37. Tube Replacement
When trouble occurs, check the power cord connection and the
control settings before removing any tubes. If tube failure is
suspected, use the tube s u b s t i t u t i o n m e t h o d (a b e l o w ) t o c h e c k
the tubes.
Caution: Do not rock or rotate a tube when removing it from
a socket; pull it straight out with a tube puller.
a.
Tube.
Substitution
Method. Replace
tube ( b
a
suspected
below) with a new tube. If the equipment still does not work,
remove the new tube and put back the original tube. Repeat this
procedure with each suspected tube until the defective tube is
located.
b.
Replacing
Tubes
in
Test
Set,
Electron
Tube
TV-2(*)/U.
Check the tubes in the tube tester as follows:
( 1 ) Remove the chassis from the case (par. 36).
( 2 ) Remove the shields of the 6X4 or 6X4W tubes (V2 and
V3) by pressing down on the shield and rotating coun-
terclockwise until it is released.
( 3 ) Release
the
retainer
of
the
83
tube
(V1)
by
pressing
down on the spring which engages the threaded portion
of
the
supporting
stud;
remove
the
retainer
from
the
tube.
( 4 ) Use a tube puller to remove the tube. If a tube puller is
not available, allow the tube to cool, and then grasp it,
and pull the tube straight up.
( 5 ) If a tube marking has become illegible, label the tube as
s o o n as it is removed.
tube (a above)
(6) Replace
the
with
one
of
the
running
spares.
( 7 ) Set the tube (or a replacement) in the socket and secure
it (by replacing tube retainer or shield).
( 8 ) Replace the chassis in the case (par. 36b).
38. Preferred-Type Tubes
A preferred-type electron tube, type 6X4W, has been developed
as
a
direct
replacement
for
nonpreferred-type
6X4.
The
6X4W
tube is used in the power supply. When replacement of a 6X4
type tube is necessary, replace it with a 6X4W type tube. Do not
substitute a 6X4 tube for a 6X4W tube.
