Table of Contents
Advertisement
)
4-1
GENERAL
The Model 71lA Power Supply is designed conserva-
tively for long component life, and it is probable
that tube replacement will correct a majority of the
difficulties which may develop. Tube replacement
instructions are given in paragraph 4-3.
The maintenance data provided in this section as-
sumes that maintenance personnel are familiar with
the operating procedures and circuit theory given
in Sections II and
ill,
respectively.
As a guide in tracing the cause of substandard oper-
ation, a troubleshooting chart is provided in para-
graph
4-9. The chart indicates causes and remedies
for certain specific troubles. Where the cause of
the trouble is of a more obscure nature than the
possibilities covered by the chart, the instrument
should be tested to localize the failure to the section
in trouble. General data on localization procedures
is
given in paragraph 4-10.-
After locating the source and eliminating the cause
o(trouble, the instrument should be tested and ad-
justed. Rated performance specifications are given
at the front of this instruction book.
4-2
COVER REMOVAL
On
both cabinet
and
rack models, the cover is fastened
to the chassis at the rear with two screws. To re-
move the cover, remove the screws, and slide the
cover to the rear and off the instrument.
NOTE: When replacing the cover, pull the power
cable through the opening in the rear of the cover.
Be sure the cable
is
free of the cover along the entire
length of the cable so that it cannot get caught be-
tween chassis and cover as the cover is slid onto
the instrument.
Sect. IV Page 1
SECTION IV
MAINTENANCE
4-3
TUBE REPLACEMENT
a.
General - Any tube in the Model 711A may
be replaced by a tube which has corresponding
standard RETMA characteristics.
In
general,
neither checks or adjustments are required when
tubes are replaced except in the case of the main
and secondary control tubes, V3B and V4B.
b.
Replacement of V3 and V4 - After replacement
of either of these tubes, check the low end and
the high end of the d-c output-voltage range and,
if
required, adjust R31 and/or R33 to bring the out-
put within rated limits.
c.
Low-End and High-End Adjustments - The
ad-
justments for R31 and R33 are brought out to
the upper side of the deck, and are identified in
Figure 4-2.
Check low end of range:
1) Turn FINE and COARSE control maximum ccw.
2) Note voltmeter indication; if not zero volts, ad-
just variable resistor R31 to obtain zero volts.
Check high end of range:
1) Turn FINE and COARSE control maximum cw.
2) Note voltmeter indication; if not 500
vol~s,
ad-
just variable resistor R33 to obtain 500 volts.
Check low end of range again:
1)
If
zero volts not obtained, adjust R31 to obtain
zero volts, and then check high end of range and
adjust R33 to obtain 500 volts.
2) The settings of R31 and R33 are interdependent.
Continue to adjust for zero and 500 volts until they
are obtained simultaneously.
Advertisement
Table of Contents
