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

241

Check relay 1A8K1.

Relay checks good.

Yes: step 285

No: replace relay 1A8K1.

242

Connect multimeter between 1A3A5-E5 and

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 243

ground.

No: step 246

243

Set signal generator to 0 dB and 100% modulation.

Oscilloscope displays waveform similar to Fig. 4-2L.

Yes: step 244

Connect oscilloscope probe to 1A4XA113, ground

No: step 247

lead to ground.

244

Connect multimeter between 1A4A6-E16 and

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 245

ground.

No: step 285

245

Connect multimeter between 1A4XA1-L and

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 296

ground.

No: step 297

246

Check relay 1A8K1.

Relay checks good.

Yes: step 285

No: replace relay 1A8K1

247

Connect oscilloscope probe to 1A3XA2-11, ground

Oscilloscope displays waveform similar to Fig. 4-2M.

Yes: step 248

lead to ground.

No: step 249

248

Connect multimeter between 1A3XA4-7 and

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 290

ground.

No: step 287

249

Connect multimeter between 1A3XA2-7 and

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 295

ground.

No: step 287

250

Connect multimeter to Speaker Driver CCA

Multimeter indicates + 28 VDC 1.5 VDC.

Yes: step 291

1A1A1-E1.

No: step 251

251

Connect multimeter between 1A6A1-8 and ground.

Multimeter indicates + 40 VDC 1.5 VDC.

Yes: step 252

No: step 253

252

Connect multimeter between 1A6A1-9 and ground.

NOTE

If no, set mode switch to OFF. Walt approximately 15

seconds then set mode switch to LSB and repeat step. If

still no, go to step 263.

Yes: step 255

Multimeter indicates + 28 VDC 1.5 VDC.

No: step 263

253

Check 1A6Q101 and 1A6R2.

Components check good.

Yes: step 285

No: replace faulty

component.

254

Connect multimeter between junction of 1A6CR1

Multimeter indicates 46 VAC or more

Yes: step 255

and 1A6CR3 and the junction of 1A6CR2 and

No: Replace transformer

1A6CR4.

1A6T1.

255

Check fuse 1A6F1.

Fuse checks good.

Yes: step 261

No: step 256

256

Check component 1A6Q101.

Component checks good.

Yes: step 257

No: replace transistor

1A6Q101; and replace

fuse 1A6F1.

257

Connect multimeter between 1A6XA1-J and

Multimeter indicates between 450 ohms and 650 ohms.

Yes: step 258

ground.

No: step 259

258

Remove Regulator Board 1A6A1.

Connect

Multimeter indicates 850 ohms or more.

Yes: replace fuse 1A6F1

multimeter on 1A6A1 between 1A6A1-E and

No: replace fuse 1A6F1

1A6A1-R.

and go to step 286

259

Remove Regulator Board 1A6A Connect

Meter indicates between 450 ohms and 850 ohms.

Yes: replace fuse 1A6F1

multimeter between 1A6XA1-J and ground.

No: step 260

260

Check component 1A6Q104.

Component checks good.

Yes: replace fuse 1A6F1

and go to step 285.

No: replace 1A6Q104; and

replace fuse 1A6F1.

261

Check diodes

1A6CR1,

1A6CR2,

1A6CR3,

Diodes check good.

Yes: step 262

1A6CR4.

No: replace faulty

component.

262

Check components 1A6R1, 1A6C5, and 1A6C6.

Components check good.

Yes: step 285

No: replace faulty compo-

nent.

263

Check transistor 1A6Q101 and resistor 1A6R2.

1A6Q101 and 1A6R2 check good.

Yes: step 286

No: replace faulty compo-

nent.

264

Set mode switch to OFF. Remove ANTENNA

Components check good.

Yes: step 285

COUPLER CONTROL (para. 3-12). Check

No: replace faulty compo-

components 1A2R1, 1A2R2 and 1A2R3.

nent.

4-19