DIRECT SUPPORT, GENERAL SUPPORT,
AND DEPOT MAINTENANCE
unless it is obvious that it is necessary. Ad-
justment of the contact-adjusting screw is
a. The following procedures are required at
necessary when the reed vibrates in a surging
the direct, support, general support, and depot
or intermittent manner or when the sparking
maintenance levels.
occurs between the contact points. If the ad-
b. The vibrator contacts are the most likely
justment is required, only a slight clockwise
source of trouble. If the vibrator contacts be-
or counterclockwise turn of the contact-adjust-
c o m e dirty, they will disrupt the vibrating
ing screw is required (refer to b below for the
frequency of the reed and will distort the out-
a d j u s t m e n t procedures). The adjustment of
p u t . The vibrator contacts should be burn-
the contacts of these units is different from
ished at weekly intervals to assure proper op-
the adjustment of contacts of similar vibrator
eration of the vibrator. If the vibrating fre-
power ringers, since, in these units, the contact
quency of the reed is erratic or distorted, burn-
gap must be kept as tide as possible. Closing
ish the contacts as indicated in paragraph 4-2.
the contact gap will not increase the output
If the unit remains inoperative after the con-
frequency or amplitude, but will cause spark-
tacts have been burnished, perform the adjust-
i n g and rf interference and can prevent re-
m e n t procedures given in paragraph 43.
s t a r t i n g of the ringer. If adjustment is re-
quired, refer to the adjustment procedures giv-
en in b below.
a. Disconnect the 115-volt ac, 60-cps power
b. Adjustment.
from the unit.
C a u t i o n : A weight of the pendulum type
b . Remove the cover from the TA-248/TT
reed. Never attempt to change the position
o r TA-248A/TT.
of the weight on the reed. The weight is prop-
c. Burnish the vibrator contacts very light-
erly positioned to insure efficient pendulum
ly with a burnishing tool.
action.
Caution: Never file the contact points. Fil-
( 1 ) Remove the cover from the TA-248/-
ing will damage the contact surfaces.
TT or TA-248A/TT.
( 2 ) Carefully turn the contact-adjusting
d. Reconnect the 115-volt ac, 60-cps power to
s c r e w slightly clockwise or counter-
the unit.
clockwise until the vibrating-reed
e. Observe the reed vibration. If the reed
f r e q u e n c y is uniform and the reed
fails to vibrate or the frequency remains er-
vibrates continuously.
ratic and distorted, adjust the contact-adjust-
( 3 ) After the adjustment has been made,
ing screw as indicatedd in paragraph 43.
remove the 115-volt ac, 60-cps power
from the unit.
( 4 ) Reapply power to the unit.
a. General. The only adjustment that is re-
( 5 ) Observe that the reed vibrates upon
q u i r e d in the TA-248/TT or TA-248A/TT is
reapplication of power to the unit; if
t h e contact-adjusting screw adjustment. The
it does not, readjust the contact-ad-
T A - 2 4 8 / T T and TA-248A/TT are preadjusted
justing screw slightly ( (2) above).
before they are received by the using organi-
( 6 ) Repeat the procedures given in (3),
zation. Additional initial adjustment is usually
(4), and (5) above. If the reed fails
not necessary. Do not make this adjustment
