2400-902-01 (G - Feb 2006)
Model 2400 Service Manual 4-12
Troubleshooting
Battery replacement
WARNING Disconnect the instrument from the power line and all other equipment
before changing the battery.
The volatile memories of the Model 2400 are protected by a replaceable battery when power is
off. Typical life for the battery is approximately ten years, but the battery should be replaced if
the voltage drops below 2.5V regardless of age. The battery should be suspected if the instru
-
ment no longer retains calibration constants, or buffer data or user-defined operating parame-
ters, such as instrument setups, source memory, and math expressions. If the battery is absent
or totally exhausted, the display will show the “Reading buffer data lost” or “DC calibration
data lost” message shortly after the Model
2400 is switched on.
NOTE Calibration constants and user-defined parameters will be lost when the battery is
replaced. The Model 2400 must be re-calibrated (Section 2) after the battery is
replaced.
The battery is a 3V wafer-type lithium cell (Keithley part number BA-44), which is located on
the digital board. Use only the recommended part number. Replacement of the battery requires
removal of the case cover, analog shield, and analog board assembly. (See Section 5.)
WARNING There is a danger of explosion if battery is incorrectly replaced. Replace
only with the same or equivalent type recommended by the manufacturer.
Dispose of used batteries according to federal, state, and local laws.
WARNING The precautions below must be followed to avoid personal injury.
• Wear safety glasses or goggles when working with lithium batteries.
• Do not short the battery terminals together.
• Keep lithium batteries away from all liquids.
• Do not attempt to recharge lithium batteries.
• Observe proper polarity when inserting the battery in its holder.
• Do not incinerate or otherwise expose the battery to excessive heat
(>60•C).
• Bulk quantities of lithium batteries should be disposed of as a
hazardous waste.
To replace the battery, first locate its holder. Use a small, non-metallic tool to lift the battery so
that it can be slid out from under the retainer spring clip.
The new battery should be reinstalled with the “+” terminal facing up. Lift up on the retaining
clip and place the edge of the battery under the clip. Slide the battery full into the holder.
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