NO OPERATION FOR ANY POSITION OF TEL-REMOTE-RADIO SWITCH.

TM 11-5820-477-30

Table 2-4. Troubleshooting, Local Control Unit (cent).

Malfunction

Test or Inspection

Corrective Action

NOTE

In later units of the A-, B- and C- models, ringing signals are applied through an RF filter

assembly. Check the continuity of the RF filter (figures FO-6 through FO-8) if the call

lamp or the buzzer of either control unit is not activated.

4. NO OPERATION FOR ANY POSITION OF TEL-REMOTE-RADIO SWITCH.

Step 1. Check switch S101 by checking for battery voltage at contact 5 when switch is in ON position.

If defective, replace (paragraph 2-14).

Step 2. Check capacitor C111.

If defective, replace (paragraph 2-13).

Step 3. Check switch S102 for continuity of switch contacts for each position.

If defective, replace (paragraph 2-14).

5. TELEPHONE COMMUNICATIONS ARE RECEIVED, BUT NOT SENT OUT TO REMOTE CONTROL UNIT.

Step 1. Check for defective preamplifier (audio amplifiers Q101 and Q102) by checking for battery

voltage at terminal 2 of component board A102.

If defective, replace Q101 and/or Q102 (paragraph 2-13).

Step 2. Check connectors P102 and J104 for continuity (pins A, C, H, J).

Replace defective connector(s) (paragraph 2-13).

Step 3. Check for defective switch S102. Check continuity of switch (section A front, contacts 3 and 11,

section B front, contacts 8 and 5).

If defective, replace (paragraph 2-14).

Step 4. Check audio line transformer T101 by checking winding resistance between terminals 1 and 2

If defective, replace (paragraph 2-13).

Step 5. Check for defective AUDIO connector J101 by checking continuity of connector (pins A, C, D).

If defective, replace (paragraph 2-14).

6. TELEPHONE COMMUNICATIONS ARE SENT OUT BUT NOT RECEIVED BY LOCAL CONTROL UNIT.

Step 1. Check audio line transformer T101 by checking winding resistance between terminals 3 and 4

If defective, replace (paragraph 2-13).

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