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TTS
26B
Section 3
3 . 1 9 MEASURINCI
70
BREAK ON
THE
M
LEAD.
The following provides for Measuring
Ol e
B r e a k on an
M lead (See fig. 3-3b):
ACTION
a.
With no power applied to the s e t , check the
position of the m e t e r pointer.
b. After adjustment b a c k off the adjustment s c r e w
slightly to r e m o v e mechanical contact between the
adjustment s c r e w and the m e t e r m e c h a n i s m .
c.
FIRST i n s e r t the 310-type plug of the power
supply patch c o r d into the 4 8 VOLT jack of the
s e t observing the p r o p e r tip and s l e e v e polarity,
and then connect i t to the 48-volt d c supply.
d .
T u r n the SEND P P S switch to any position
except PWR O F F .
e .
If the l a m p s did not light r e m o v e the d c power
supply f i r s t , then change the 310- type plug to the
other
48
VOLT jack, and then r e c o n n e c t the 4 8 -
volt dc power supply.
f.
To m e a s u r e
7' 0
b r e a k of b a t t e r y and open pulses
on the M l e a d turn the RECEIVE switch to
REC
B&O,
(Id) o r if this switch i s u s e d i n the fully
clockwise position to t r a n s f e r c o n t r o l to the SEND
o r SEND AND R E C switch turn that ( l a t t e r )
switch to
E & M
-
DROP, E
=G&O,
M
=B&O. T o
m e a s u r e
' $ 0
b r e a k of b a t t e r y and ground pulses
on the M lead t u r n t h e R E C E I V E switch to REG
B&G ( M ) o r if this switch
is u s e d fully clockwise
to t r a n s f e r c o n t r o l to the SEND o r SEND ANDREC
switch t u r n the ( l a t t e r ) switch to E & M - D R O P
E
=G&O, M = B & G .
g.
T u r n the METER
CIRCUIT
switch to
O/o
BREAK DIRECT.
RESULT
I t should b e on the 100 line of the
70
BREAK s c a l e
( m e t e r e l e c t r i c a l
0.
)
If i t i s off adjust the s c r e w
on the f r o n t of the m e t e r c a s e to bring i t to
this line.
T h i s c o m p l e t e s the mechanical adjustment of
the m e t e r e l e c t r i c a l 0.
If connection is not m a d e i n this s e q u e n c e a
b a t t e r y supply f u s e m a y blow.
If the wrong 48-
volt jack
is
used diode prote-ction within the s e t
will p r o t e c t the s e t f r o m d a m a g e , but the s e t
w i l l
be inoperative in succeeding s t e p s
.
This t u r n s the s e t on.
The LINE ( E ) and DROP
( M ) l a m p s should light.
If they do light proceed
to s t e p f .
If they do not light proceed to s t e p e .
The light should light.
If they s t i l l do not the
s e t probably i s not receiving power.
~f
the c i r c u i t h a s high inductance o r capacitance
which m a y d i s t o r t the pulse wave shape the
METER CIRCUIT switch should be turned to
70
BREAK THRU METER RELAY o r e r r o n e o u s
r e a d i n g s m a y be obtained.
h.
The FUNCTION, LINE ( E ) and DROP (M)
keys should be n o r m a l u n l e s s r e q u i r e d f o r
simultaneous sending.
The LINE ( E ) key may
be operated to O F F
HOOK
to make the trunk
busy toward the l i n e .
T h e E X T
DIAL
CIRCUIT
switch i s not i n the m e a s u r i n g c i r c u i t .
The
SPARK SUP turnbutton is not involved.
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