5-2 Disassembly Model 2500 Service Manual
Introduction
This section explains how to handle, clean, and disassemble the Model 2500 Dual Photo-
diode Meter. 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
touching the PC board traces while you are repairing the instrument. The preamp boards
and certain mother board areas 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 you must solder 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 122°F (50°C), low-humidity environ-
ment for several hours.
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