CHART 2-24. Control Unit Troubleshooting (Sheet 2 of 12)

TM 11-5820-670-30

2-26. TROUBLESHOOTING CHARTS. (CONT)

CHART 2-24

Control Unit Troubleshooting

(Sheet 2 of 12)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

5. Speaker noise present/not present (SQUELCH switch at CARR).

Check for short circuit between main connector J9101 pin V and ground. (See FO-13.)

Replace switch S9106 (para 2-78).

6. Speaker noise not present (SQUELCH switch at DIS).

Check for infinite resistance between main connector J9101 pin V and ground. (See

Repair wiring or replace S9105 (para 2-81) or squelch switch S9106

7. Gearbox kHz indicator does not track with frequency selected.

Check continuity of the kHz tuning control lines to ground. (See table

on sh 9, FO-13

and FO-21.) Also see resistance tables sh 4.

Repair wiring or replace frequency selector switches S9103 (para 2-80)

8. Gearbox MHz indicator does not track with frequency selected.

Check continuity of the MHz tuning control lines to ground. (See table

on sh 11, FO-13

and FO-21.) Also see resistance tables sh 4.

Repair wiring or replace frequency selector switches S9101 (para 2-83)

9. Antenna coupler simulator test failure.

Check continuity of the MHz tuning control lines to ground. (See table

on sh 10,

FO-13 and FO-21.) Also see resistance tables sh 4.

Repair wiring or replace frequency selector switches S9101 (para 2-83)

2-115