Table 4-2. Checkout/Troubleshoot the Receiver-Transmitter RT-1277/URC-92 (cont)

TM 11-5820-873-34

Table 4-2. Checkout/Troubleshoot the Receiver-Transmitter RT-1277/URC-92--Continued

STEP

ACTION

INDICATION

NEXT STEP

265

Connect multimeter across contacts of 1A2DS2.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes:replace 1A2DS2

and

go to step 13.

No: step 285

266

COUPLER STATUS FAULT indicator went out.

Yes: step 267

No: step 270

267

COUPLER STATUS TUNING indicator illuminated.

Yes: step 268

No: step 271

268

COUPLER STATUS TUNING indicator went out.

Yes: step 269

No: step 285

269

Connect multimeter across contacts of 1A2DS1.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes:

replace

1A2DS1 and

go to step 13.

No: step 285

270

Check switch 1A2S2.

Switch 1A2S2 checks good.

Yes: step 285

No: replace switch

1A2S2

271

Connect multimeter across 1A2DS3.

Multimeter indicates less than 300 ohms.

Yes: step 285

No: replace 1A2DS1

and

go to step 13.

272

Set mode switch to OFF.

Check REFL FWD POWER

REFL FWD POWER MONITOR switch 1A2S1

Yes: step 273

MONITOR switch 1A2S1.

checks good.

No: replace switch

1A2S1.

273

Check relay 1A8K1.

Relay checks good.

Yes: step 285

No:

replace relay

1A8K1.

274

Set mode switch to OFF.

Check REFL FWD POWER

REFL FWD POWER MONITOR switch 1A2S1

Yes: step 276

MONITOR switch 1A2S1.

checks good.

No: replace switch

1A2S1.

275

Check resistor 1A1R49.

Resistor checks good.

Yes: step 285

No: replace resistor

1A1R49.

276

Continuity check 1A8P2-17 to 1A2S1 center

Continuity checks good.

Yes: step 292

contact.

No: step 285

277

Connect multimeter between 1A6A2-E6 and ground.

Multimeter indicates + 13 VDC.

Yes: step 278

No: step 280

278

Set mode switch to OFF. Check 1A6T1 primary windings;

1A1T1 primary windings check good.

Yes: step 279

1A6TB2-7 to 1A6TB2-6

No: replace

1A6TB2-7 to 1A6TB2-5

transformer

1A6TB2-7 to 1A6TB2-4

1A6T1.

1A6TB2-7 to 1A6TB2-2

1A6TB2-7 to 1A6TB2-1

279

Continuity check the following:

Continuity checks good.

Yes: step 303

1A6TB2-7 to 1A6A2-E2

No: step 285

1A6TB2-6to 1A6A2-E1

1A6TB2-4 to 1A6A2-E5

1A6TB2-2 to 1A6A2-E8

1A6TB2-2 to 1A6A2-E3

1A6TB2-1 to 1A6A2-E4

280

Connect multimeter between 1A8J5-11 and ground.

Multimeter indicates + 13 VDC.

Yes: step 285

No: step 281

281

Check DC fuse 1A8F3.

Fuse checks good.

Yes: step 282

No:

replace fuse

1A8F3.

282

Check relay 1A8K2 for proper DC operation.

Relay checks good.

Yes: step 283

No:

replace relay

1A8K2.

283

Check components 1A8Q1, 1A8CR2, 1A8CR3, 1A3CR4,

Components check good.

Yes: step 284

1A8CR5, lA8R1, 1A8R2.

No:

replace faulty

compo-

nent.

284

Check switch 1A1S13-C front.

Switch checks good.

Yes: step 284

No: replace switch

1A1S13.

285

Repair and/or replace wiring and connectors as necessary.

---

286

Replace and/or repair Regulator Assy 1A6A1. Use conventional

---

troubleshooting methods for repair. (If 1A6F1 is blown--check

1A6Q104 ).

287

Replace and/or repair Receiver/Exciter Mother Board 1A3A5.

---

Use conventional troubleshooting methods for repair. (If no

modulation when mic is

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