f. R e l e a s e t h e P R E S S T O T E S T P 4 s w i t c h .
g. For twin-indicator tubes, operate the SCREEN and SUP-
PRESSOR SELECTORS switches to the positions specified in
t h e second line of the tube test data roll chart.
h. A g a i n d e p r e s s t h e P R E S S T O T E S T P 4 s w i t c h . I f t h e t u b e
is good, the indicator now should be open, or, in the case of twin-
indicator tubes, indicator No. 1 should be open and indicator No. 2
should be closed.
i. P e r f o r m a n e m i s s i o n t e s t o n t h e t r i o d e o f e l e c t r o n - r a y i n -
dicators with triode sections, such as 6U5 (par. 23). The control
settings for the emission test are specified in the third entry of
t h e same tube on the tube test data roll chart (par. 12).
Test ballast tubes as follows:
a. P e r f o r m t h e o p e r a t i o n s i n d i c a t e d i n p a r a g r a p h 1 5 .
b. O p e r a t e t h e F I L - S E L E C T O R S s w i t c h t o t h e p o s i t i o n s p e c i -
fied in the tube test data roll chart for the tube under test. All
other switches and controls should be in their safety positions
(par. 15d).
d. Turn the ON-OFF power switch to the ON position.
e. Turn the SHORT TEST switch to the V position.
f. D e p r e s s a n d h o l d d o w n t h e P R E S S T O T E S T P 1 s w i t c h .
Operate the FIL+ SELECTORS switch to each of the positions
specified in the tube test data roll chart. The FIL.-CONT.
S H O R T lamp should glow in every position noted. If it does not,
discard the ballast tube.
g. R e p e a t t h e p r o c e d u r e s i n d i c a t e d i n b t h r o u g h f a b o v e f o r
each listing of the tube.
To check an indicator lamp or other lamps with miniature
b a y o n e t or screw-type bases, proceed as follows:
a. O P E R A T E T H E F I L - S E L E C T O R S s w i t c h t o p o s i t i o n 2 .
b. O p e r a t e t h e F I L + S E L E C T O R S s w i t c h t o p o s i t i o n 7 .
c. Operate the FILAMENT RANGE switch to the correct
voltage for the lamp under test. This voltage usually is marked
on the lamp base.
d . Operate the ON-OFF power switch to the ON position.
e. Adjust the FILAMENT fine control until the FILAMENT
VOLTS meter indicates the exact voltage specified for the lamp.
