VOR zero performance test failure.

TM 11-6625-2976-40

2-7. TROUBLESHOOTING TABLE. (CONT)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

4. VOR modulation or 9960 fm deviation performance test failure. (Cont)

Test frequency divider output in the following manner.

Step 2.

Connect oscilloscope (time base: 5 ms; vertical: 2v/div; sync: INT) to J16

(FO-4). Verify square wave, 0(base) to 7 (peak) v 1 v amplitude.

Connect frequency counter to J16. Verify frequency 240 0.024 Hz. Connect

oscilloscope to J6 (FO-4). Verify square wave, 0(base) to 6.2 (peak)

v 0.3 v amplitude.

Connect frequency counter to J6. Verify frequency 60 0.006 Hz.

Connect oscilloscope toJ17 (FO-4). Verify square wave, 0 (base) to 6.2

(peak) v 0.3 v amplitude.

Connect frequency counter to J17. Verify frequency 30 *0.003 Hz.

If waveforms, voltages, or frequencies are incorrect, replace circuit

card assembly A6.

Check VOR modulation adjustment (para 2-11).

Step 3.

Adjust VOR section of circuit card assemblyA6 (para 2-11).

If unable to aline, or if test set fails performance test after adjustment,

replace circuit card assembly A6.

5. VOR zero performance test failure.

If error is 45 degrees or more, perform VOR bearing selector alinement

Step 1.

Step 2.

Check setting of A6R72.

With equipment set up as in performance test, adjust A6R72 (FO-4) for

000.00 indication on zifor.

If performance test indicates fault still exists, go to MALFUNCTION item 4, step 3.

Step 3.

6. LOC or glide slope modulation performance test failure.

Perform steps 1 and 2 under MALFUNCTION item 4.

Step 1.

If percent MOD is incorrect, see paragraphs 2-9 and 2-10.

Step 2.

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