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 (O 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 7-43. Two levels of voltage, one for V1 and the other for V2, are produced by DAC U070 and
U080 (CMOS 8-bit buffered multiplying 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 tri-state output,
74LS245) on the A06 MPU/Display board through the A08 Mother board, and U045 (74LS245) on the A05 board.
4434-573
Figure 7-43. 338 Threshold test.
7-119
Summary of Contents for 318
Page 119: ...318 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 182: ...338 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 253: ...318 ___________________ TROUBLESHOOTING TREES ...
Page 344: ...338 TROUBLESHOOTING TREES ...
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Page 519: ...TM 11 6625 3145 14 318 338 4434 925 318 Acquisition Module Wiring Diagram ...
Page 520: ...TM 11 6625 3145 14 318 338 4434 926 318 338 Mainframe Wiring Diagram ...
Page 521: ...TM 11 6625 3145 14 318 338 4434 926 338 Acquisition Module Wiring Diagram ...
Page 522: ...TM 11 6625 3145 14 318 338 4434 928 Figure 9 1 318 A01 Input A Board Component Locations ...
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Page 528: ...TM 11 6625 3145 14 Figure 9 3 318 338 A03 ACQ Control Board Component Locations ...
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Page 542: ...TM 11 6625 3145 14 Figure 9 8 318 338 A10 CRT Board Component Locations ...
Page 544: ...TM 11 6625 3145 14 Figure 9 9 318 338 A11 Inverter Board component Locations ...
Page 546: ...TM 11 6625 3145 14 Figure 9 10 318 338 A12 Regulator Board Component Locations ...
Page 551: ...TM 11 6625 3145 14 Figure 9 12 338 A01 Input A Board Component Locations ...
Page 553: ...TM 11 6625 3145 14 318 338 SERVICE ...
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Page 555: ...PIN 058584 ...