Replacing Non-Volatile Ram Battery - Keithley 2701 Service Manual

Section 3: Routine maintenance
Make sure that all plug-in module connections are de-energized and disconnected before replacing
module amps fuses.
To replace the 7700 plug-in module amps fuses:
1. Turn off the power and disconnect the power line and external connections from the 7700.
2. Open the 7700 top cover.
3. Locate the amps fuses for CH21 and CH22.
4. Remove the circuit board from the bottom plastic housing by removing the two bottom screws.
5. De-solder the blown CH21 or CH22 fuse as required, taking care not to damage the circuit board
or spread solder flux around the board.
6. Install a new 3 A, 250 V fast-blow fuse, Keithley part number FU-107-1.
Do not use a fuse with a higher current rating than specified or module damage may occur.
7. Solder the new fuse in place using organic (OA based) flux solder, again taking care not to
damage the circuit board or spread solder flux around the board.
8. Carefully clean the repaired area of the circuit board with a foam tipped swab or brush dipped in
pure water, then blow dry the board with dry nitrogen gas. Allow the board to dry for several hours
in a 50 °C low-humidity environment before use.
9. Re-install the circuit board into the plastic housing, then close the top cover.

Replacing non-volatile RAM battery

The 2701 has a rechargeable lithium ion battery for non-volatile RAM. Use the procedure below to
replace the battery, if required. Refer to
drawings in for more information.
There is a danger of explosion if the battery is incorrectly replaced. Replace only with the part
designated by the corresponding Keithley Instruments part number. Dispose of used
batteries according to the manufacturer's instructions.
The following procedure is intended only for qualified service personnel. Do not perform this
procedure unless you are qualified.
Disconnect the line cord and all connecting wires from the 2701 before removing the top cover.
The precautions below must be followed to avoid personal injury.
3-6
Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual
Disassembly (on page 5-1) and the component layout
2701-902-01 Rev. B / December 2018