TM 11-6625-444-14-1
and select VDC and FILT mode. Insure 10V
(3) Apply +10V DC to A10TP4 (-) and TP5
range is selected.
(+). The voltage at A10TP5 and TP3 shall not
(6) Apply a 3V rms 1 %, 60 Hz signal to the
change more than 100 V.
INPUT terminals.
(4) Apply -10V DC to A10TP4 (-) and TP5
(7) Rotate SAMPLE RATE control to obtain
(+), observing that the voltage at A10AP5 and
a digital readout change of approximately two
TP3 does not change more than 100 V. If the
times a second. The digital readout shall be less
preceding are ae specified, the active filter is
than +20 digits. If not, the filter circuitry is
operational. If not, the gain control circuitry is
defective.
fault y.
(5) Disconnect equipment from the voltmeter
Section III. MAINTENANCE OF THE VOLTMETER
switches. Retain gaskets freed upon removal of
6-9. General
front panel.
This section contains maintenance instructions
(6) Unplug and remove printed circuit boards
for the voltmeter. The information is arranged
(E), except for the printer output (A7) which is
under paragraphs covering disassembly,
attached to the rear panel by its cabling.
cleaning, repair and replacement, assembly, and
(7) Cut cable ties (F) at rear panel INPUT
component selection. Contents of these
harness, inner chassis transformer secondary
paragraphs provide complete maintenance in-
harness, and inner chassis power harness (two
structions for the voltmeter. The performance
places).
tests in paragraph 6-16 shall be conducted after
(8) Disconnect transformer harness at TB2
any repairs are made.
(G) and pull harness out and away from chassis.
6-10. Disassembly
(9) Tag and disconnect rear INPUT terminal
a. Covers. Removal of dust covers and inner
wiring (H). Wiring is disconnected by removing
guard covers is accomplished as follows:
nuts on each terminal.
(1) Remove top dust cover by unlocking
(10) Tag, unsolder, and disconnect rear panel
fasteners.
GUARD wire (I) at inner chassis.
(2) Remove top guard cover by removing four
(11) Remove 12 screws (J) which attach inner
attaching screws.
chassis to main chassis.
(3) Remove bottom dust cover by unlocking
(12) Pull EXT REF input cabling (K) toward
fasteners.
the front of the voltmeter until free of the inner
(4) Remove bottom guard covers by
chassis.
removing single attaching screw from rear-most
(13) Slide the inner chassis (L) forward while
cover and four screws from front bottom cover.
at the same time lifting its rear section up. Make
b. Panels and Chassis. Disassembly of the
sure the cable clamp and cabling on the right, rear
panels and chassis is done in the sequence shown
section stays on the side near the rear of the
in figures 6-23 and 6-24 together with the
voltmeter.
Referenced letters
following procedure.
(14) Remove the inner chassis by first pulling
correspond with those shown in figures 6-23 and
the inner chassis up and towards the rear of the
6-24.
voltmeter. Next, apply a slight upward pressure
(1) Remove each control knob (A, fig, 6-23)
on the front section (M) just before the RANGE
on the front panel by loosening setscrews.
and SAMPLE RATE controls bottom out against
(2) Remove seal nuts (A) associated with
the chassis and then remove the inner chassis.
each control shaft.
Position inner chassis as shown in figure 6-23.
(3) Tag, unsolder, and disconnect wire from
(15) Straighten locking tabs on the DC
GUARD terminal (B) at terminal riveted to
ZERO and RATIO FULL SCALE poten-
chassis.
tiometers (N, fig. 6-24) and then push them free of
(4) Tag and unplug wiring (C) to INPUT
panel.
terminals.
(16) Remove inner front panel by removing
(5) Remove the front panel (D) by first
seven screws (0).
removing 12 attaching screws. Next, carefully
(17) Remove four screws (P) which secure the
pull front panel free of pushbutton switches while
rear of the display assembly (A14).
at the same time removing the boots from the
