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

212

Check switch 1A1S8-D, rear, and 1A1R23 thru R33.

Components check good.

Yes: step 213

No: replace faulty compo-

nent.

213

Check switch 1A1S10-13, rear, and 1A1R34 thru R44.

Components check good.

Yes: step 214

No: replace faulty compo-

nent.

214

Check switch 1A1S15.

Switch checks good.

Yes: step 285

No: replace switch

1A1S15

215

Connect multimeter across 1A1DS2 contacts.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: replace 1A1DS2

No: step 216

216

Set mode switch to OFF. Remove front panel.

Check

Continuity checks good.

Yes: step 285

continuity between 1A1R52, pins A and B.

No: replace VFO control

1A1R52.

217

Connect multimeter between synthesizer mother board 1A4A6-J

Multimeter indicates + 7.6 VDC 0.8 V.

Yes: step 217

and ground. Rotate VFO control.

No: step 221

218

Connect multimeter between Translator CCA, 1A4XA3-A and

Multimeter indicates + 7.6 VDC 0.8 V.

Yes: step 219

ground Rotate VFO control.

No: step 221

219

Connect multimeter between 1A4A6-8 and ground.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 220

No: step 285

220

Connect multimeter between 1A4XA3-1 and ground.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 222

No: step 297

221

Check VFO control 1A1R52.

Component checks good.

Yes: step 285

No: replace VFO control

1A1R52.

222

Adjust 1A4A3-L22 for a multimeter indication of 7.6 VDC 0.8

L22 adjusts within tolerance.

Yes: step 6d

VDC.

No: step 299

223

Check relay 1A1K101 and diode 1A1CR17.

Components check good.

Yes: step 224

No: replace faulty compo-

nent.

224

Check FREQ CONTROL switch 1A1S15.

Component checks good.

Yes: step 285

No: replace switch

1A1S15

225

Set signal generator to 0 dB. Connect oscilloscope probe to

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

Yes: step 226

1A3XA2J2-5.

No: step 230

226

Connect oscilloscope probe to 1A3XA4J4-11, ground lead to

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

Yes: step 227

ground.

No: step 232

227

Connect multimeter between 1A3XA4J4-9 and ground.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 228

No: step 287

228

Connect multimeter between 1A3XA4J4-13 and ground.

Multimeter indicates between + 2.0 VDC and + 8.0

Yes: step 229

VDC.

No: step 290

229

Connect VTVM (AC) to 1A3XA4J4-6, ground lead to ground.

VTVM indicates 0.1 V minimum.

Yes: step 290

No: step 187

230

Connect frequency counter to 1A5A4-E1, ground lead to

Frequency counter indicates 29.9994 MHz.

Yes: step 231

ground.

No: step 292

231

Connect frequency counter to 1A3XA1J1-15, ground lead to

Frequency counter indicates 29.9994 MHz.

Yes: step 233

ground.

No: step 234

232

Connect oscilloscope probe to 1A3XA2J2-11, ground lead to

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

Yes: step 287

ground.

No: step 236

233

Connect multimeter between 1A3XA1J1-3 and ground.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 235

No: step 239

234

Connect frequency counter to 1A3A5-E22, ground lead to

Frequency counter indicates 29.9994 MHz.

Yes: step 287

ground.

No: step 285

235

Connect multimeter between 1A3XA1J1-P and ground.

Multimeter indicates between + 2.0 VDC and + 8.0

Yes: step 298

VDC.

No: step 287

236

Connect multimeter between 1A3XA2J2-9 and ground.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 237

No: step 287

237

Connect multimeter between 1A3XA2J2-3 and ground.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 238

No: step 287

238

Connect multimeter between 1A3XA2-P and ground.

Multimeter indicates between + 2.0 VDC + 0.8 VDC.

Yes: step 295

No: step 287

239

Connect multimeter between 1A3A5-E1 and ground.

Multimeter indicates + 12 VDC 0.8 VDC.

Yes: step 287

No: step 241

240

Connect multimeter between mode switch, 1A1S13-2 and

Meter indicates + 12 VDC 0.8 VDC.

Yes: step 285

ground.

No: replace 1A1S13.

4-18