Keysight E1412A, Service Manual

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90 E1412A 6 1/2 Digit Multimeter Service Guide
Service Repair/Maintenance Guidelines
Soldering Printed Circuit Boards
Most of the components on the PC assembly are suface mount components.
Surface mount components should
only be removed using soldering irons or
desoldering stations expressly designed for surface mount components. Use of
conventional solder removal equipment will almost always result in permanent
damage to the printed circuit board and will void your Keysight Technologies
factory warranty.
A few of the components in the multimeter have plated-through
holes that allow a solder path to both sides of the insulating material. For these
components (such as replacing fuses F750 or F752 with axial-lead components),
soldering can be done from either side of the board with equally good results.
When soldering to any circuit board, keep in mind the following guidelines.
–
Do not use a sharp metal object such as an awl or twist drill, since sharp
objects may damage the plated-through conductor.
– Avoid unnecessary component unsoldering and soldering. Excessive
replacement can result in damage to the circuit board and/or adjacent
components.
– Do not use a high power soldering iron on etched circuit boards, as
excessive heat may lift a conductor or damage the board.
–
Use a suction device or wooden toothpick to remove solder from
component mounting holes. When using a suction device, be sure the
equipment is properly grounded to prevent electrostatic discharge from
damaging CMOS devices.
Post-Repair Safety Checks
After making repairs to either the the Keysight E1412A multimeter, inspect the
multimeter for any signs of abnormal internally generated heat, such as
discolored printed circuit boards or components or evidence of arcing. Determine
and correct the cause of the condition. Then run the self-test (*TST? command) to
verify that the multimeter is functional.