Memory Batteries - Hach Sigma 950 Instrument Manual

Maintenance

9.7 Memory Batteries

Random Access Memory (RAM) is a very reliable data storage medium for
microprocessor applications however, a RAM requires power at all times to store its data.
If power is removed, the data stored in the RAM chip is lost. Therefore, it is not feasible to
power the RAM chips from the meter power supply because you would lose your data
and program settings every time you unplugged the power cord. A separate battery
pack located inside the flow meter powers the RAM chips and the real time clock.
The memory batteries (P/N 2709) keep the program entries and logged data stored in
RAM memory when the main power fails or is removed for transport or replacement.
The memory batteries consist of two 1.5 V dc C cells. They are located below and behind
the CPU circuit board, which is attached to the inside of the front panel assembly. They
are easily replaced without having to remove the CPU board assembly. Use only good
quality alkaline C cells as replacements.
If the memory battery voltage falls too low to properly maintain the program settings, a
warning: "MEMORY BATTERY" will flash in the lower right corner of the display to alert
you to replace the batteries. The meter uses a very small amount of energy from the
memory batteries during normal operation.
To replace the memory batteries, refer to Figure 17 and proceed as follows:
1. Download all data before removing the batteries. All data will be lost from the meter
when the batteries are removed.
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2. Pull back on and open the Velcro retaining strap.
3. Remove the old batteries and insert the new ones.
4. Refasten the Velcro retaining strap.
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