Keithley 6521, Instruction Manual, Page: 43 / 65

4
Service Information
4-1
WARNING
The information in this section is in-
tended only for qualified service person-
nel. Some of the procedures may expose
you to hazardous voltages that could re-
sult in personal injury or death. Do not
attempt to perform these procedures
unless you are qualified to do so.
4.1 Introduction
This section contains information necessary to service the
Model 6521/22 scanner card and is arranged as follows:
4.2 Handling and cleaning precautions:
Discusses han-
dling precautions and methods to clean the card should
it become contaminated.
4.3 Performance verification:
Covers the procedures nec-
essary to determine if the scanner card meets stated
specifications
4.4 Special handling of static-sensitive devices:
Reviews
precautions necessary when handling static-sensitive
devices.
4.5 Principles of operation:
Briefly discusses circuit
operation.
4.6 Troubleshooting:
Presents some troubleshooting tips
for the Model 6521/22 including relay replacement pre-
cautions.
4.2 Handling and cleaning precautions
Because of the high-impedance areas on the Model 6521/22,
care should be taken when handling or servicing the card to
prevent possible contamination. The following precautions
should be observed when servicing the card.
4.2.1 Handling precautions
• Handle the card only by the edges and shields.
• Do not touch connector insulators.
• Do not touch any board surfaces or components not as-
sociated with the repair.
• Do not touch areas adjacent to electrical contacts.
• When servicing the card, wear clean cotton gloves.
• Do not store or operate the card in an environment
where dust could settle on the circuit board.
• Use dry nitrogen gas to clean dust off the board if
necessary.
4.2.2 Soldering considerations
Should it become necessary to use solder on the circuit
board, observe the following precautions:
• 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 areas when the repair
has been completed. Use pure water along with clean
cotton swabs or a clean soft brush to remove the flux