AT&T Bell System Plant Series Adjustment Procedure

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BELL SYSTEM PRACTICES
Plant Series
SECTION 024-107-500
Issue 2, July, 1957
AT&TCo Standard
143-TYPE AMPLIFIERS
TESTS, ADJUSTMENTS AND REQUIREMENTS
CONTENTS
1. GENERAL
2. TESTS AND ADJUSTMENTS
IA) Primary Power Voltage Measurement
and Adjustment . •
18)
Electron Tube Tests .
IC) Gain and Gain-Frequency Tests .
ID) Noise Tests .
IE) Preliminary Trouble Locating Tests .
IF) Operating Voltage Measurements
IG) Electrolytic Capacitor Testing and
Replacement
1. GENERAL
PAGE
1
1
2
2
4
5
5
7
1.01
This section covers the tests and require-
ments that apply to amplifiers coded 143A,
143B, and 143C. Information is included which
will be of help in clearing cases of trouble.
1 .02
This issue reorganizes the section to sim-
plify testing procedures and to include in-
formation on recent production changes. Since a
general revision _ has been mp.de, arrows ordinarily
used to indicate changes have been omitted.
1.03
In amplifiers made after October 20, 1956
changes were made in the high voltage
filter arrangement. Two schematic diagrams are
now provided in this section. Figs. 7 and 8 show
the circuits used before and after the changes
were made.
1.04
Section 024-107-300 lists the initial and
routine tests which are
to
be made on the
143-type amplifiers. The circuit description and
parts lists are contained in Section 024-107-100.
Input circuit variations are covered in Section
024-107-101.
1.05
Test Equipment: The tests throughout
this section require the use of the follow-
ing test equipment:
1- KS-14510 Volt-Ohm-Milliammeter or
Weston 779A Analyzer
1 - KS-15560 Tube Tester
1 - 19C Oscillator or equivalent
1 - 13A, 21A, or 30A Transmission Measur-
ing Set
1- 5A Attenuator
1 - Output Pad as described in Paragraph
2.10
1 - 600-Ohm Resistor, 106A or ½-watt
carbon
3 - W3U Shielded Cords or equivalent
1.06
Tests should be made in the order listed.
2. TESTS AND ADJUSTMENTS
IA) Primary Power Voltage Measurement and
Adjustment
2.01
The purpose of this test is to determine
which connections on the power trans-
former T2 are to be connected to the ac supply
terminals. In the current model of the 143-type
amplifier, T2 is a KS-14254 transformer, on which
the winding taps are brought out to terminal lugs.
Connections to amplifier terminals 21 and 22 are
made by means of straps. In earlier models of
the 143-type amplifier, T2 is a KS-13820 trans-
former on which the winding taps are brought
out as flexible leads. In this case the proper flex-
ible leads are terminated directly on terminals
21 and 22.
2.02
Apparatus:
KS-14510 Volt-Ohm-Milliammeter or Weston
779A Analyzer
2.03
Procedure:
(1)
Adjust the voltmeter to a range suitable
for an ac reading of over 100 volts.
(2) Measure the supply voltage at the fuse
box or other convenient point between the
fuse box and the amplifier.
Copyright, 1957, by American Telephone and Telegraph Company
Printed in U.S.A.
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