Table 6-8. Power Supply (A1) Checks

TM 11-6625-444-14-1

Table 6-8. Power Supply (A1) Checks

logic (fig. 6-6), and display (fig. 6-7). The test

c. Analog Section. The circuitry comprising

point locations are shown in figure 6-1. Since each

this section is contained in both the buffer (All)

assembly performs a number of separate func-

and active filter (A10) assemblies. Test point

tions, they are divided into the independent

locations are shown in figure 6-1. To determine if

table

for

subsections

shown in

6-9

a trouble exists in the analog section, proceed as

troubleshooting. Troubleshooting of the digital

follows:

section is performed in the sequence shown in

(1) Connect a battery powered differential

figures 6-14 and 6-15. Waveforms of commands

voltmeter to A10TP4 () and TP3 (+).

and signals referenced in figures 6-14 and 6-15 are

(2) Select the 10 volt range and VDC function

contained in figures 6-16 through 6-22. Included

on the voltmeter.

with each waveform is the applicable test point

(3) Turn on the voltmeter and then apply a

and timing relation to other waveforms. All

+10V DC input to its INPUT terminals.

waveforms were taken with the voltmeter placed

(4) Verify that the differential voltmeter

in the continuous measurement mode.

indicates -10V DC is present at A10TP4 and

NOTE

TP3.

The storage cycle can be by passed if there

( 5 ) Apply full-scale input voltages on

is a suspicion that it is faulty (usually

selected ranges of 1,100, and 1,000 volts. Each

indicated by flashing digits) by jump-

range shall produce the same voltage specified in

ering A1TP5 (+5V) to A14TP2. If the

step (4).

readout is then observed to be correct, the

NOTE

storage cycle circuitry is faulty. If not,

For inputs of less than full-scale on any

the trouble lies elsewhere.

range, the voltmeter will produce a

proportionally less voltage at A10TP4

and TP3. For example, a +10V DC input

Table 6-9. Digital Section Subsections

in the 100-volt range will produce -1V

DC.

(6) If the voltage at A10TP4, and TP3 is not

correct, the trouble is in the analog section which

consists of the buffer and active filter assemblies.

Applicable troubleshooting procedures for each of

these assemblies are contained in paragraph 6-8.

If the voltage at A10TP4 and TP3 is correct, the

section.

digital

lies

the

problem

Troubleshooting procedures for the digital section

are contained in d below.

NOTE

Remove t h e ratio input (A3) when

troubleshooting the digital section.

d. Digital Section. The digital section circuitry

is contained in the A-to-D converter (fig. 6-5)

6-16