OPERATION
The SELECT button selects what is to be displayed and the CONTROL button controls what is
displayed. The SELECT button sequentially selects GMT, LT, ET, and back to GMT. The CONTROL
button starts and resets elapsed time, ET, when momentarily pushed. The normal operation of the
MB800 cannot result in accidental time setting.
SETTING GMT
Select GMT for display with the SELECT button. Press SELECT and CONTROL simultaneously to
enter set mode. The tens of hours digit will start flashing. The CONTROL button controls the
flashing digit and each button push increments the digit. Once the flashing digit is set the SELECT
button selects the next digit to be set, from left to right across the display. After the last digit is set a
final press of the SELECT button will exit the clock from set mode. The display annunciator will
resume its normal flashing to indicate the clock is running.
SETTING LT
Select Local Time, LT, using the SELECT button. Enter the set mode by pressing both buttons, the
tens of hours digit will start flashing. The setting operation is the same as GMT except that minutes
are already synchronized with GMT and can not be set in LT.
TEST MODE
Hold the SELECT button down for 3 seconds and the display will read 88:88. All three annunciators
will be on.
ET COUNT UP
Select ET for display. Pressing the CONTROL button will start ET counting up in minutes, seconds
until reaching 59 minutes and 59 seconds. ET will then start counting in hours and minutes up to 99
hours and 59 minutes. Pressing CONTROL again will reset ET to zero.
ET COUNTDOWN
Select ET for display, enter set mode by pressing both buttons. The countdown timer can now be
set. Entering the time is identical to GMT time setting. When the time is entered and the last digit is
no longer flashing the clock is ready to start the countdown. Momentarily pressing the CONTROL
button starts the countdown. When the count reaches zero the displays flashes and the external alarm
is activated. Pressing either SELECT or CONTROL will deactivate the alarm. ET continues counting
up.
KEEP ALIVE INPUT: 14V or 28V
ALARM OUTPUT: Open collector 25 mA.
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