Table 4-3. Troubleshooting Table, AVIM (continued)

TM 55-4920-411-13&P

TROUBLE

PROBABLE CAUSE

REMEDY

Replace

Defective lamp, S4

All of lamps L1-L6 do not light when LAMP TEST

(Fig 4-1 and 4-2)

switch is pressed.

R10-R15 or CR1-CR4 on dis-

play board or associated com-

(Para 4-8)

ponents

LAMP TEST switch, S4

(Replace

None of lamps L1-L6 light when LAMP TEST

(Fig 4-5)

switch is pressed.

Repair

+ 12 vdc or + 5 vdc supply on

(Para 4-8)

signal generator board

Replace

R31 on signal generator board

Frequency output impedance exceeds 1.5 K ohms.

(Fig FO-1)

(Para 4-8)

Monitor oscil -

Clock oscillator out of adjust-

Output frequencies out of tolerance.

lator frequency

ment

between test

(Para 4-9)

points 1 ( + ) and

3 (-) (Figure 4-7)

and adjust R 10

for 1 microsec-

ond period

Replace

One of frequency signal gener-

No output frequency when FUNCTION SWITCH

ator components defective

is in any position other than 0% or output frequen-

(See Fig 4-7 and

cy out of tolerance and oscillator frequency cor-

FO-1).

rect.

(Para 4-9)

Replace

T2, CR10, CR1l, A4, A5,

No temperature output

Replace

C27 on signal generator board

(Para 4-10)

or associated components.

Replace

TEMP OUTPUT poten-

Temperature output several volts high and unad-

tiometer open (R1) or

justable.

associated components

(Para 4-10)

4-5