AT&T Bell System Plant Series Alignment Instructions page 10

(
(
(
(
(
(
(
( c) Momentarily operate key SYN RST on
display panel. Lamp OUT SYN should go
out and stay out. The meter should read ap-
proximately 4. Disconnect cords.
( d) Connect a rear terminal test cord to the
LD cord and ground the sleeves. This can
be done using the BRIDGE GS jacks in the
20A if they are available. Operate key WBFl
to F2. (Relay Fl releases and F2 operates.)
Repeat (c).
( e) Restore keys to normal.
(f) If this test fails, see 4.30.
4.30
In making wide-band data distortion meas-
urements, the input from the data test
cord circuit is connected directly to the data
(FSK) demodulator by the DMC relay. The sig-
nal path can be checked, as shown as follows under
the conditions of 4.29.
Reading
Location
Fl F2
Trouble
dbm
Signal not re-
TS(B)
ceived from 20A
-27 ±4 -22 ±4
or short in
44,34
wiring* that
follows
TS(B)
Same as above
Relay DMC
37,27 or wiring
* The wiring can be traced using SD-73022-01,
Sheet B6.
SUPERVISORY-DEMODULATOR-DEMULTIPLEXER
4.31
The following sequence of tests may be
performed to check the performance of the
su pervisory-demod ulator-demulti plexer.
155
1,
SECTION
107-302-500
A. Supervisory Input Signal
4.32
Verification That a 906A Generated Super-
visory Dotting Signal Appears at the Super-
visory Input: Arrange the data signal generator
to deliver a 95.5-bps dotting signal at the super-
visory frequency (350 ±35 cps) on the GT and
GR leads by operating GEN .MODE switch to DOT
and by operating the SEND SUPV switch. Estab-
lish a back-to-back signal path through the 20A
toll testboard by operating relays SSV, SV, and
RDl. This is accomplished by operating the SUPV
key and the DATA READ key. A supervisory
dotting signal should be present on leads CT and
CR in the 906A. A measurement of level at AMPO
will verify this; the level should read between -14
and - 22 dbm at test point AMPO on CP52 as read
with the high impedance TVM with respect to
ground. If this requirement cannot be met, sec-
tionalize the signal generator, modulator, and/or
channel selector circuits for the trouble.
B. Supervisory Lamp States-Bias Adjustment
4.33
Verification of Proper Supervisory Lamp
States in Conjunction with a Bias Adjust-
ment if This Adjustment is Required: Operate
relays CH7 and TMC by operating the CHAN
SEL switch (20A toll testboard) to position
SUPV; relay SMC in the 906A will then operate
TMC. A supervisory dotting signal should be-
come available at the demodulator output. This
dotting signal is then demultiplexed and directed
to the CH lamp circuit through the contacts of
relay SMC. The demultiplexed dotting signal
should result in a steady on signal for the SYN
lamp and alternate frame flashing for each of
the six CH lamps. The sequence of flashing is
lamps 1, 3, and 5 simultaneously on, followed by
lamps 2, 4, and 6 simultaneously on, repeating
until this test connection is broken down.
If
these
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