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TM 11-6625-3145-14
Maintenance: Troubleshooting-318/338 Service
12.
THRESHOLD TEST
Program: THRSH
Function:
Power on - Threshold V1 and Threshold V2 are set for several levels to produce Threshold V3 at - 0.2V or +0.2V. For
every setting the comparator will detect the Threshold V3 level relative to ground and the MPU checks the comparator’s
output against the expected data (0 or 1).
Troubleshooting - Threshold V1 and Threshold V2 are programmed from -10.0V to +10.0V incrementally with 0.1V steps
in order to generate the saw-tooth waveform.
Description: Refer to Figure 7-11. Two levels of voltage, one for V1 and the other for V2, are produced by DAC U070
and U080 (CMOS 8-bit buffered multiplexing DAC, AD7524) on the A05 ROM/Threshold board. When the MPU writes
data into these DACs, this setting is latched inside. The data is supplied from U216 (octal bus transceiver with 3-state
output, 74LS245) on the A06 MPU/Display board through the A08 Mother board, and U045 (74LS245) on the A05 board.
When the MPU writes at I/O address E0
hex
the WR and CS signals are sent to U070 (DAC V1) to latch the data. WR and
CS for U080 (DAC V2) are caused by the MPU’s access at I/O address E1
hex
. The WR signal is delivered from U150C
(quadruple 2-input positive NOR gate, 74LS02) on the A05 board, which comes from U214 (octal buffer/line driver with 3-
state output, 74LS240) on the A06 board. CS for these DACs are generated by U092B (dual 2-line to 4-line
decoder/demultiplexer, 74LS139) on the A05 board.
A number less than 80
hex
programs the DAC for positive output, and a number more than 80
hex
progarms it for negative
output centered on GND (80
hex
) in 0.1V steps. The actual output of these DACs is 1/4 of that specified in the
THRESHOLD menu.
The settings and expected data are as follows;
7-26
Содержание 318
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Страница 253: ...318 ___________________ TROUBLESHOOTING TREES ...
Страница 269: ...TM 11 6625 3145 14 Maintenance Troubleshooting 318 338 Service Figure 7 7 318 Word recognizer test ...
Страница 278: ...TM 11 6625 3145 14 Maintenance Troubleshooting 31 8 338 Service Figure 7 10 318 N and DELAY counter test 7 25 ...
Страница 313: ...TM 11 6625 3145 14 Figure 7 19 Troubleshooting Tree 8 Data Acquisition ACQ A01 A02 Sheet 4 of 6 7 60 ...
Страница 344: ...338 TROUBLESHOOTING TREES ...
Страница 362: ...TM 11 6625 3145 14 Maintenance Troubleshooting 318 338 Service 4434 567 Figure 7 39 338 Word recognizer test 7 109 ...
Страница 371: ...TM 11 6625 3145 14 Maintenance Troubleshooting 318 338 Service 4434490 Figure 7 42 338 N and DELAY counter test 7 118 ...
Страница 421: ...TM 11 6625 3145 14 Maintenance Troubleshooting 318 338 Service Figure 7 55 Troubleshooting Tree 12 T H A01 A02 7 169 ...
Страница 517: ...TM 11 6625 3145 14 318 338 4434 923 318 Block Diagram ...
Страница 518: ...TM 11 6625 3145 14 318 338 4434 924 338 Block Diagram ...
Страница 519: ...TM 11 6625 3145 14 318 338 4434 925 318 Acquisition Module Wiring Diagram ...
Страница 520: ...TM 11 6625 3145 14 318 338 4434 926 318 338 Mainframe Wiring Diagram ...
Страница 521: ...TM 11 6625 3145 14 318 338 4434 926 338 Acquisition Module Wiring Diagram ...
Страница 522: ...TM 11 6625 3145 14 318 338 4434 928 Figure 9 1 318 A01 Input A Board Component Locations ...
Страница 526: ...TM 11 6625 3145 14 ...
Страница 528: ...TM 11 6625 3145 14 Figure 9 3 318 338 A03 ACQ Control Board Component Locations ...
Страница 532: ...TM 11 6625 3145 14 ...
Страница 536: ...TM 11 6625 3145 14 ...
Страница 538: ...TM 11 6625 3145 14 ...
Страница 539: ...TM 11 6625 3145 14 ...
Страница 540: ...TM 11 6625 3145 14 ...
Страница 541: ...TM 11 6625 3145 14 ...
Страница 542: ...TM 11 6625 3145 14 Figure 9 8 318 338 A10 CRT Board Component Locations ...
Страница 544: ...TM 11 6625 3145 14 Figure 9 9 318 338 A11 Inverter Board component Locations ...
Страница 546: ...TM 11 6625 3145 14 Figure 9 10 318 338 A12 Regulator Board Component Locations ...
Страница 548: ...TN 11 6625 3145 14 Figure 9 11 318S1 338S1 A07 Serial RS232 Non Volatile Memory Board Component Locations ...
Страница 551: ...TM 11 6625 3145 14 Figure 9 12 338 A01 Input A Board Component Locations ...
Страница 553: ...TM 11 6625 3145 14 318 338 SERVICE ...
Страница 554: ......
Страница 555: ...PIN 058584 ...