Table 5-3. Troubleshooting Guide (cont)

TM 11-5820-917-13

Table 5-3.

Troubleshooting Guide - Continued

Location /cause

Indication

For Time: Fault in 3-path programmer

1A4A1, frequency standard 1A6, or dis-

play elements 1A9.

Indicates fault in any of 6025 regulated DC

In receiver self-test, RCVR

supplies, or 4028 unregulated supplies.

red lamp lights.

Alternatively, the lamp will also indicate

a fault occurring in any functional part

of the control circuits processing the

received signal. A malfunction can be

isolated to either the power supplies or

the receiver functional circuits, as

follows:

a. Stop the synthesizer sweep by

setting MODE switch to MAN position,

pressing STOP switch, and then pressing

RESET switch.

b. Repeat the receiver test. If the

red RCVR lamp lights, the fault is in the

power supplies; if the green RCVR lamp

lights, the fault is in a receiver functional

circuit.

Check that BATT switch is ON. Replace

10. In receiver self-test, BATT

batteries (if non-rechargeable supply).

red lamp lights.

Check and recharge (if rechargeable

supply).

Cursors stored in off screen frequency.

11. Less than six cursors available

Perform cursors erase (paragraph 3-8,

for storage/display.

step e). If fault remains, turn off system

power, wait several seconds, turn on

system power.

WARNING

Use extreme care when making internal adjustments with power on.

Potentially lethal voltages are present in the receiver.

5-13. POWER SUPPLY ADJUSTMENT. The 4028 unit supplies regulated DC

voltages of +5, +12, -12, and +24 VDC for its own receiver circuitry, and unregu-

lated +5, +11, +20, -20 and +35 VDC for use by the 6025 unit. None of the DC

voltages require adjustment; however, they should be periodically checked to

detect diminished operation. Voltages are checked using a multimeter and meas-

uring the value as marked in figures 5-2 through 5-9 for each of the module test

5-5