(a)  
The D setting is used for changing the day display. When in this position, the day display automatically advances at a rate of one day per second up to maximum value of 31, 30, 29, or 28 depending on the month setting and reincrementing from 01. The month display does not change.

 (b)  
The M setting is used for changing month display. When in this position, the month display automatically advances at a rate of one month per second, up to maximum value of 12 and reincrementing from 01. The day display does not change.

 (c)  
The Y setting is used for changing year display. Turning the SET switch to Y position will cause the two right hand digits to update one year per second up to maximun value of 99 and reincrementing from 00. The two left hand digits will be blank.

The lower display provides elapsed time (ET) from 00 hours 00 minutes to 99 hours 59 minutes and chronographic time (CHR) from 00 minutes to 99 minutes. (The sweep second hand shows the seconds for chronographic time.) Control of this display is provided by the ET and CHR switches.The elapsed time (ET) control switch is located in the lower left corner. This switch operates as follows:

 (a)  
In the RESET position, the ET display is blanked and the elapsed time indication is set to zero. The RESET position is spring loaded to return the switch to the HLD positon.

 (b)  
The HLD (hold) position of the switch freezes the ET display at the present indicated value.

 (c)  
In the RUN position, time is accumulated from the last hold or reset condition. The display automatically advances from this indicated value.

The CHR switch is located in the upper left corner. This switch operates as follows:

 (a)  
The first press of the switch starts the chronograph running.

 (b)  
A second press of the switch freezes the chronograph display at the present indicated value.

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757 MAINTENANCE MANUAL
 (c)  
A third press of the switch resets the CHR accumulator to zero. The contents of the ET accumulator is then displayed. If the ET accumulator contains zero, the elapsed time display is blanked with the sweep second hand to zero.

 (d)  
Chronograph operation replaces the display of the elapsed time, but does not affect the internal operation of the ET accumulator.

 B. Clock Switch
 (1)  
The Captain's and F/O's clock switches are located on either side of the glareshield (P7).

 (2)  
The CHR and remote clock switches are connected in parallel and operate the chronograph display. Both switches cycle the chronograph through the start, hold and reset functions of the chronograph mode.

 C. FMC
　
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本文鏈接地址：757 AMM 飛機維護手冊 儀表 CHAPTER 31 - INSTRUMENTS 1(28)