12 Safety function
__ a SG self test
_ The SG is able to be self tested because its digital outputs X, Y, blanking and color are connected via a test register on the SG bus.
 b Watch dog
_ A watching circuit controls the activity of SG LSI, and of the DSDL link. It is retriggered by the INIT signal which is supplied by the SG after reception of status word by the DSDL. When the watch dog falls, then the DSDL receiver is re-initialized one time.
 c Short power interrupt detection : SPID
_ Power interrupts shorter than 2 ms will not induce any change of the DU state. Power interrupts less than 3 seconds will not destroy the program RAMs content, but MASK RAMs will need reloading. In this case, a short power interrupt signal will be generated. More than 3 seconds power interrupts can destroy all RAMs content. A long power interrupt signal will then be provided.
 d DU temperature
_ Two temperature levels are detected:
 -
The lowest one generates an alarm

 -
The second one cuts off the DU.

 e DU anomaly
_ This signal results from a failure considered as possibly dangerous for the CRT. The failures are:
 -plus or minus 5V, plus or minus 15V, + 100V, - 170V trouble detection
 -Cathode amplifiers over-load detection
 -Beam minimum velocity monitoring
 -VHV anomaly.
 (5) Interconnection Board The interconnection board is located at the rear of the display unit and electrically interconnects the lateral boards by flexible circuit and connectors. The interconnection board includes the DU connector and several components, including lightning protection, line fuses, Normal/Alternate and DU ON/OFF relays.
R 1EFF : 001-049, 051-099, 101-105, 151-199, 1 31-63-00Page 71 1201-299, 301-302, 1Config-1 May 01/05 1 1 1CES 1 NOTE : These relays are driven by discrete signals. The DU OFF

____ discrete is generated by the brightness knob.
 (6) Low Voltage Power Supply (Ref. Fig. 024) Low voltage power supply consists of two parts:
 -
the first one provides an intermediate pre-regulated 40 V voltage

 -
the second one provides, via two parallel transformers, all the necessary voltages to the different modules of the DU:

 -6.3 V  CRT
 25 V  VHV
 5 V  Symbol generator
 -170 V  |
 100 V  |
 +34 V  |
 -34 V  |
 +17 V  |  Analog board
 -17 V  |
 +15 V  |
 -15 V  |

 This structure permits the use of small size transformers, the second part operating from a constant input voltage and thus minimizing the filtering components.
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 Low Voltage Power Supply - Block Diagram
 Figure 024

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 (7) DU Reactions to Power Interrupts

 -------------------------------------------------------------------------------| POWER INTERRUPT | CONSEQUENCE | |------------------------|----------------------------------------------------| | t < 2.5 ms | No effect | |------------------------|----------------------------------------------------| | | . LV power supply restarts within 200 ms. | | 2.5 ms < t < 3 s | . VHV power supply restarts within 300 ms after | | | recovery of LV power (= 500 ms global). | | | . Masks RAMs may be lost. | |------------------------|----------------------------------------------------| | 3 s < t < 11 s | . Same as above, plus : | | | . All RAM contents may be lost. | |------------------------|----------------------------------------------------| | t > 11 s | . Same as above, plus : | | | . Cathode heating temporization (about 12 seconds).|
 NOTE : In any case, the DU is able to dialogue with the DMC as soon
____ as the LV power supplies are available, i.e. 200 ms after the main power is on.
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 DISPLAY MANAGEMENT COMPUTER (DMC) / LIQUID CRYSTAL DISPLAY (LCD) CONTRO L AND
_____________________________________________________________________________
 INTERCONNECTION - DESCRIPTION AND OPERATION
___________________________________________
 1. General
_______
 A. EIS Sections
 (1) EIS breakdown Here after are listed all the EIS sections as well as a summary or their contents: 31-60-00 Electronic Instrument System (EIS)
 -
The purpose of this document is to give a general description of the EIS (EIS components, display functions, reconfiguration capabilities...). 31-61-00 Electronic Instrument System (EIS)/ Control
　
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