Keithley 2700, Service Manual

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5-2 Disassembly
Introduction
This section explains how to handle, clean, and disassemble the Model 2700 Multimeter/
Data Acquisition System. Disassembly drawings are located at the end of this section.
Handling and cleaning
To avoid contaminating PC board traces with body oil or other foreign matter, avoid touch-
ing the PC board traces while you are repairing the instrument. Some circuit board areas, espe-
cially those under the motherboard shield, have high-impedance devices or sensitive circuitry
where contamination could cause degraded performance.
Handling PC boards
Observe the following precautions when handling PC boards:
• Wear cotton gloves.
• Only handle PC boards by the edges and shields.
• Do not touch any board traces or components not associated with repair.
• Do not touch areas adjacent to electrical contacts.
• Use dry nitrogen gas to clean dust off PC boards.
Solder repairs
Observe the following precautions when soldering a circuit board:
• Use an OA-based (organic activated) flux, and take care not to spread the flux to other
areas of the circuit board.
• Remove the flux from the work area when you have finished the repair by using pure
water with clean, foam-tipped swabs or a clean, soft brush.
• Once you have removed the flux, swab only the repair area with methanol, then blow
dry the board with dry nitrogen gas.
• After cleaning, allow the board to dry in a 50°C, low-humidity environment for several
hours.