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TTS 26B
Section 3
3. 3
The different c i r c u i t s which c a n be s e t u p
under the c o n t r o l of the RECEIVE, and the SEND
o r SEND AND REC switches a r e shown i n s i m p l i -
fied f o r m in f i g s . 3 - 2 , 3-3 and 3-4.
T h e s e i l l u s -
t r a t e the c i r c u i t s connected to the v a r i o u s jacks
for different positions of t h e s e s w i t c h e s when the
FUNCTION switch i s in the SEND AND R E C posi-
tion.
T h e s e d i a g r a m s s e r v e a s a quick r e f e r e n c e
to d e t e r m i n e what t e s t connections a r e being used.
3 . 4 When the c o v e r of the s e t has been unlatched
and opened i t can e 3sily be detached by sliding i t
to the right.
If c o r d s o r o t h e r i t e m s s t o r e d in the
c o v e r a r e needed the hinged lid within the cover
may be opened by f i r s t turning the thumbscrew
which s e r v e s a s the latch.
3 . 5 CORDS
3 . 6 P o w e r supply c o r d
-
T h i s c o r d should provide
tip and s l e e v e connections f r o m the s e t to
48
volts d c
(40 to 5 5 volts). It should have a 3 10-type plug on the
end toward the s e t . It should be i n s e r t e d into the s e t
FIRST
,
and then connected to the power s o u r c e i n
o r d e r to avoid blowing a f u s e when connection i s
made to the s e t . F o r the s a m e r e a s o n i t should be
disconnected f r o m the power s o u r c e FIRST before
i t i s removed f r o m the s e t . P o w e r m a y be obtained
f r o m the c e n t r a l office b a t t e r y o r f r o m a N E C P S I 0 1
power supply unit o r equivalent.
3.
7
Sending and receiving t e s t c o r d s
-
Two
-
conductor c o r d s ( t i p and r i n g ) a r e sufficient for
dl t e s t s except those s p e c i a l t e s t s r e q u i r i n g
d i r e c t a c c e s s to the contacts of the SEND r e l a y ,
and t e s t s involving sending on the s l e e v e s .
F o r
these s p e c i a l t e s t s a 3-conductor c o r d ( t i p , ring
and s l e e v e ) i s needed.
All c o r d s should be equip-
ped with a 310-type plug on the end toward the
signaling t e s t s e t .
3 . 8 Monitoring and S u p e r v i s o r y L a m p s .
The tip
of the E AND M SIGNALING LINE jack in the s e t
i s connected to the tip of the DROP jack, and
s i m i l a r l y the ring of the LINE jack to the ring of
the DROP jack.
Hence, when the line and d r o p
jacks of a t r u n k , on the line s i d e of E and M s i g -
naling equipment, a r e patched to t h e s e , the con-
tinuity of the trunk i s completed through the s e t .
However, i t should .be noted that during the patch-
ing operation an i n t e r r u p t i o n i n the continuity of
the trunk i s caused.
T h i s would r e s u l t in-
1
hit
that would be d e t r i m e n t a l to any d a t a being t r a n s -
mitted o v e r the t r u n k , no m a t t e r how rapidly the
patching o p e r ations a r e made.
3 .
9 After completion of this patching, when the
FUNCTION key i s i n the TEST L & D position and
the LINE ( E ) and DROP (M) k e y s a r e n o r m a l ( a t
MONITOR), r e l a y s bridging on the tip and ring
con.trol the LINE ( E ) and DROP ( M ) l a m p s to
indicate w h e t h e r o r not an idle o r busy trunk i s
connected through the LINE and DROP jacks.
Thus
these l a m p s w i l l be lighted to indicate idle trunk
conditions, o r d a r k to indicate busy conditions.
3. 10 A bridging t e s t of O/o b r e a k may be m a d e on
an E o r M l e a d .
T h e FUNCTION switch i s turned
to SEND AND R E C , the METER CIRCUIT switch to
70
BREAK DIRECT (do not u s e the low impedance
THRU METER RLY position), the TEST SEND key
i s r e s t o r e d to SEND DIAL, and the RECEIVE switch
i s turned to the a p p r o p r i a t e E o r M position.
When the a p p r o p r i a t e E and M SIGNALING
-
E o r
M jack i n the s e t i s u s e d , and
i f the trunk under
t e s t is i n s e r v i c e i t i s i m p o r t a n t that the patch to
i t s E o r M l e a d should be bridged only ( i . e. should
not open the E o r M lead of the trunk).
3 . 11 A f u r t h e r application of this m e t e r monitor
-
ing d i s c u s s e d i n the preceding p a r a g r a p h p e r m i t s
an o b s e r v a t i o n of the r e c e i v e d
70
b r e a k to be made
on the
E
o r M l e a d while the s e t i s sending on the
o t h e r of t h e s e l e a d s .
F o r this u s e theFUNCTION
key m u s t b e in e i t h e r the SEND DIAL o r the SEND
OSC position, w i t h the switches involved in send-
ing s e t a t t h e i r r e q u i r e d positions.
3.12 SENDING SIGNALS WITH A PREDETERMINED
%
BREAK.
3. 13 F i g . 3 - 3 , 3 - 3 a , 3 - 3 b show i n simplified
s c h e m a t i c f o r m the c i r c u i t f o r sending i n e a c h of
the sending positions of the SEND ok SEND AND
REC switch.
3 . 1 4 CALIBRATION FOR SENDING
Oj6
BREAK
PULSES.
The m e t e r of the T T S 26B m u s t be cali-
- - -
b r a t e d f o r the supply voltage used.
When p r o p e r l y
c alibr ated
,
the s e t w i l l o p e r a t e s a t i s f a c t o r i l y
f r o m a s t a b l e voltage supply, and the METER CAL
c o n t r o l p e r m i t s c a l i b r a t i o n of the m e t e r if the
supply voltage d o e s not l i e outside l i m i t s extending
f r o m 40 volts to 55 volts.
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