Troubleshooting Chart, CAU/CCU Alarm Panel

TM 11-5895-878-14&P

Item

Trouble Symptom

Probable trouble

Check and corrective maintenance

c. Defective Major/Minor or Audible

c. Check Alarm Panels (paras 2-14 and

Alarm panel.

2-17).

d. Defective 6 vdc power supply.

d. Remove panel from rack and check for

+ and-6 vdc outputs from power supply.

Replace defective power supply.

No alarm (gnd) output with

a. Ground alarm signal not applied to Ma- a. Check for ground at CAU alarm signal

known alarm signal on TB1.

jor/Minor Alarm panel.

output at terminal 1 of TB2. If ground is.

present, check at assigned pin on Ma-

jor/Minor Alarm Panel. If ground is not

at Major/Minor Alarm Panel, check and

repair circuit wiring.

b. Defective Major/Minor Alarm Panel.

b. If ground is found on the circuit input

pin, check the Major/Minor Alarm Panel

circuit (para 2-14).

c. Defective diode CB21 through CB40.

c. Replace defective diode.

d. Defective relay K2.

d. Remove relay K2 and substitute a

known good relay. Replace a defective

relay.

e. Defective resistor R4.

e. Disconnect power from panel and check

resistance of R4. Replace and open

resistor or one that has a high

resistance.

f. Defective transistor Q2.

f. With power disconnected, remove relay

K2 from its socket. Check transistor Q2

with ohmmeter. Replace defective

transistor.

No alarm (gnd) output with

Same as item 2 above, with trouble in Q1 Same as item 2 above. Check for ground

known alarm signal on TB3.

circuit components and exterior circuit.

at CCU alarm signal output at terminal

5 of TB2. Check diodes CR1 through

CR20, relay K1, resistor R2 and

transistor Q1.

A CAU or CCU alarm sounds

Defective transistor Q1 or Q2.

Check for shorted transistor. Replace

with no alarm signal applied

defective transistor.

to TB1 or TB3.

4-10