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METERBRIDGE
D-75 / Sep 2004
Console Clock
The Wheatstone digital clock is a six-digit time-of-day clock with LED
display. The clock is designed with CMOS circuits and an on-board crystal-
controlled time base oscillator. Clock set controls may be accessed by opening
the meterbridge cover.
Controls
The clock is controlled by two switches mounted on the VU/clock/timer
PCB assembly.
Setting the Time
The setting controls consist of two switches: MODE and SET. To set the
clock, open the meterbridge cover:
1) The control switches (mounted on the main clock PCB assembly) are
labelled "M" and "S". "M" (
Mode) is used to scroll from seconds to minutes
to hours; "S" is used to
Set the time. The procedure is to set the clock slightly
ahead of the current time, hold the second count at "00" until the current time
catches up, and then release the count.
2) Press the MODE button until the hour digits blink. Depress the SET button
until the desired hour is displayed.
3) Press the MODE button until the minute digits blink. Depress the SET button
until the desired minute count is displayed.
4) Press the MODE button until the second digits blink. Depress and hold the
SET button; the seconds display will hold at "00". When the current time
catches up to the display, release the SET button. The clock will start
counting. Hit the MODE button once more to place the clock into working
mode.
Capacitor Backup
With the meterbridge open note the super capacitor at C35. This super
capacitor is self charging. Note that the super capacitor does NOT light up the
clock display; it powers the clock crystal to keep it from losing count (it will
do this for several days).
Operational Modes
The standard factory default clock configuration is crystal-controlled, 12
hour mode, stand-alone operation. However, some operational features can be
modified using programmable dipswitch SW1 on the VU-75 PCB.
24 Hour Mode
The clock can be made to run in 24 hour mode.
SW1 position 1 enables 24 hour mode
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