
8571—Fault finding
354
NGT Transceiver System Technical Service Manual
No signalling
No signalling can be due to a loss of one of the regulated supplies, a failure in the
microprocessor and control circuit, or a problem in the transmit/audio paths.
A study of the technical description of the signalling system should assist in checking for
a signalling fault.
If there is a second system available, then swap the units to assist in identifying the faulty
unit. However, if this is not possible, it is necessary to carry out a number of the tests to
locate the area in which the signalling has failed.
Checking the master 8571
To check the operation of the master 8571:
1
Initiate a channel change and use an oscilloscope connected across the line to
observe the control tone.
The 300 Hz control tone (nominally 700 mV p–p) combined with the FSK signal
should be seen for a short period after the channel change.
1
If there appears to be no activity when initiating a channel change, check all
regulated DC supplies for the master 8571 (see
If the signalling in the master 8571 appears to be working, then a fault could be due
to a failure in the line, in the slave 8571, or the transceiver.
Checking other equipment
If the microprocessor and its associated circuits appear to be functioning, then check the
tone generator, the Bell 103 modem, and the signal path for possible failure.
Table 9: Supply voltages for the Dual Line Equaliser PCB
Supply Description
Voltage Source
B rail
+10 V regulated supply
10 V
±
0.2 V
IC6
+6 V bias
+6 V reference
6 V
±
0.6 V
junction R2/R3
+5 V bias
+5 V reference
5 V
±
0.5 V
junction R3/R4
+4 V bias
+4 V reference
4 V
±
0.4 V
junction R4/R5
Содержание NGT 2010 RF
Страница 87: ...03 01032 Issue 2 ...
Страница 88: ...03 01032 Issue 4 ...
Страница 97: ...03 01126 ...
Страница 98: ...03 01190 ...
Страница 234: ...NGT Parts lists 200 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 428: ...04 03223 ...
Страница 429: ...04 03562 CODAN ...
Страница 430: ...04 03437 ...
Страница 431: ...04 03533 ...
Страница 432: ...08 05513 ...
Страница 433: ...08 05514 sheet 1 ...
Страница 434: ...08 05514 sheet 2 ...
Страница 435: ...08 05628 sheet 1 ...
Страница 436: ...08 05628 sheet 2 ...
Страница 437: ...08 05628 sheet 3 ...
Страница 438: ...08 05628 sheet 4 ...
Страница 439: ...04 03125 ...
Страница 440: ...08 05300 ...
Страница 441: ...08 05522 ...
Страница 442: ...08 05523 ...
Страница 443: ...08 05524 ...
Страница 444: ...04 03201 ...
Страница 445: ...08 05470 ...
Страница 446: ...04 03423 ...
Страница 447: ...08 05986 sheet 1 ...
Страница 448: ...08 05986 sheet 2 ...
Страница 449: ...04 03133 ...
Страница 450: ...08 05317 ...
Страница 451: ...04 03109 ...
Страница 452: ...08 05266 ...
Страница 453: ...04 03108 sheet 1 ...
Страница 454: ...04 03108 sheet 2 ...
Страница 455: ...08 05265 ...
Страница 456: ...04 03106 sheet 1 ...
Страница 457: ...04 03106 sheet 2 ...
Страница 458: ...04 03106 sheet 3 ...
Страница 459: ...08 05261 sheet 1 ...
Страница 460: ...08 05261 sheet 2 ...
Страница 461: ...04 03095 ...
Страница 462: ...08 05235 ...
Страница 463: ...04 03378 sheet 1 ...
Страница 464: ...04 03378 sheet 2 ...
Страница 465: ...04 03378 sheet 3 ...
Страница 466: ...04 03378 sheet 1 ...
Страница 467: ...04 03378 sheet 2 ...
Страница 468: ...04 03378 sheet 3 ...
Страница 469: ...08 05889 sheet 1 ...
Страница 470: ...08 05889 sheet 2 ...
Страница 471: ...08 05889 sheet 1 ...
Страница 472: ...08 05889 sheet 2 ...
Страница 473: ...04 03410 ...
Страница 474: ...04 03414 ...
Страница 475: ...08 05963 ...
Страница 476: ...08 05962 ...
Страница 477: ...08 05973 ...
Страница 478: ...04 03169 ...
Страница 479: ...08 05415 ...
Страница 480: ...08 05416 ...
Страница 481: ...08 05511 sheet 1 ...
Страница 482: ...08 05511 sheet 2 ...
Страница 483: ...04 03369 ...
Страница 484: ...08 05869 sheet 1 ...
Страница 485: ...08 05869 sheet 2 ...
Страница 486: ...08 05869 sheet 3 ...
Страница 487: ...08 05910 sheet 1 ...
Страница 488: ...08 05910 sheet 2 ...
Страница 489: ...04 03542 ...
Страница 490: ...08 06461 sheet 1 ...
Страница 491: ...08 06461 sheet 2 ...
Страница 492: ...08 06461 sheet 3 ...
Страница 493: ...08 05910 sheet 1 ...
Страница 494: ...08 05910 sheet 2 ...
Страница 495: ...04 03425 ...
Страница 496: ...08 05988 sheet 1 ...
Страница 497: ...08 05988 sheet 2 ...
Страница 498: ...04 03424 sheet 1 ...
Страница 499: ...04 03424 sheet 2 ...
Страница 500: ...08 05987 ...
Страница 501: ...04 03499 sheet 1 ...
Страница 502: ...04 03499 sheet 2 ...
Страница 503: ...08 06261 sheet 1 ...
Страница 504: ...08 06261 sheet 2 ...
Страница 505: ...04 03498 sheet 1 ...
Страница 506: ...04 03498 sheet 2 ...
Страница 507: ...08 06260 ...
Страница 508: ...04 03379 ...
Страница 509: ...08 05890 ...
Страница 510: ...15 10506 001 ...
Страница 511: ...15 10514 001 ...
Страница 512: ...04 03110 ...
Страница 513: ...08 05267 ...
Страница 514: ...04 03514 ...
Страница 515: ...08 06320 ...
Страница 516: ...04 03272 ...
Страница 533: ...03 01138 ...
Страница 534: ...03 01139 ...
Страница 560: ...High power Parts lists 246 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 604: ...04 03422 ...
Страница 605: ...08 05985 ...
Страница 606: ...04 03419 ...
Страница 607: ...08 05997 ...
Страница 608: ...04 03420 ...
Страница 609: ...08 05999 ...
Страница 610: ...04 03416 ...
Страница 611: ...08 05977 sheet 1 ...
Страница 612: ...04 03428 ...
Страница 613: ...08 05998 ...
Страница 614: ...04 03429 ...
Страница 615: ...08 06000 ...
Страница 616: ...04 03415 ...
Страница 617: ...08 05976 sheet 1 ...
Страница 618: ...08 05976 sheet 2 ...
Страница 619: ...04 03418 sheet 1 ...
Страница 620: ...04 03418 sheet 2 ...
Страница 621: ...08 05979 sheet 1 ...
Страница 622: ...08 05979 sheet 2 ...
Страница 623: ...04 03417 ...
Страница 624: ...08 05978 sheet 1 ...
Страница 625: ...08 05978 sheet 2 ...
Страница 626: ...08 05978 sheet 3 ...
Страница 627: ...04 03421 ...
Страница 628: ...08 05984 ...
Страница 629: ...04 03453 ...
Страница 630: ...08 06067 sheet 1 ...
Страница 631: ...08 06067 sheet 2 ...
Страница 632: ...08 06102 sheet 1 ...
Страница 633: ...08 06102 sheet 2 ...
Страница 634: ...04 03377 ...
Страница 635: ...08 05926 sheet 1 ...
Страница 636: ...08 05926 sheet 2 ...
Страница 637: ...04 03407 ...
Страница 638: ...08 05927 sheet 1 ...
Страница 639: ...08 05927 sheet 2 ...
Страница 653: ...NRI Brief description 260 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 654: ...03 01079 ...
Страница 680: ...NRI Fault finding 286 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 682: ...NRI Parts lists 288 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 699: ...NRI Drawings 290 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 700: ...04 03363 sheet 1 ...
Страница 701: ...04 03363 sheet 2 ...
Страница 702: ...08 05854 sheet 1 ...
Страница 703: ...08 05854 sheet 2 ...
Страница 704: ...08 05854 sheet 3 ...
Страница 705: ...04 03364 ...
Страница 706: ...08 05855 ...
Страница 707: ...04 03370 ...
Страница 708: ...08 05870 ...
Страница 720: ...3012 Brief description 300 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 721: ...03 01080 ...
Страница 723: ...3012 Brief description 302 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 737: ...3012 Parts lists 316 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 748: ...3012 Drawings 318 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 749: ...04 03366 sheet 1 ...
Страница 750: ...04 03366 sheet 2 ...
Страница 751: ...08 05860 sheet 1 ...
Страница 752: ...08 05860 sheet 2 ...
Страница 753: ...04 03367 ...
Страница 754: ...08 05861 ...
Страница 770: ...8571 Brief description 332 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 771: ...03 01108 ...
Страница 801: ...8571 Parts lists 362 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 825: ...8571 Drawings 364 NGT Transceiver System Technical Service Manual This page has been left blank intentionally ...
Страница 826: ...08 05994 sheet 1 ...
Страница 827: ...08 05994 sheet 2 ...
Страница 828: ...04 02541 ...
Страница 829: ...08 03905 ...
Страница 830: ...04 02690 ...
Страница 831: ...08 03993 ...
Страница 832: ...04 02691 ...
Страница 833: ...08 05995 ...
Страница 834: ...04 02852 ...
Страница 835: ...08 04644 ...
Страница 836: ...04 02487 ...
Страница 837: ...08 03817 ...
Страница 838: ...08 03995 ...