Chapter 5: Troubleshooting
To Check the keyboard; Troubleshooting Procedure
5–14
To Check the keyboard; Troubleshooting Procedure
Use this procedure only if you encounter key failures in the keyboard test procedure. If any knobs
fail, replace the keyboard assembly.
1 Disconnect the power cord and remove the cover.
2 Remove the front panel assembly.
See chapter 6 for instructions.
3 Remove the keyboard assembly and the cursor keyboard assembly from the front panel
assembly. Partially re-assemble the front panel assembly, including the flat-panel
display and lens, but omitting the keyboard and cursor keyboard. Re-attach the partial
assembly to the chassis.
Be sure to reconnect the display video cable and the backlight inverter cables. See chapter 6 for
instructions on removing and disassembling the front panel.
4 Separate the elastomeric keypads from the cursor keyboard and keyboard assemblies.
CAUTION CONTAMINATION CAN CAUSE INTERMITTENT OPERATION!
Be careful not to contaminate the key side of the PC board or the keypads. Dust and fingerprints
on these parts may cause intermittent key operation.
5 Set the cursor keyboard and keyboard assembly on an antistatic electrical insulated
surface.
6 Connect the cursor keyboard cable to the keyboard assembly. Connect the keyboard
cable to the oscilloscope interface board in the chassis.
You may need to set the chassis on its side to allow proper routing of the cables without straining
them.
7 Reconnect the power cable and apply power.
8 Enable the graphical interface, then start the keyboard test as described in the previous
procedure.
9 Carefully short the PC board trace, with a paper clip or screwdriver, at each
nonoperating key (as determined by keyboard test), and look for an appropriate
response on the display.
• If the display responds as though a key were pressed, replace the elastomeric keypad.
• If the display does not respond as though a key were pressed, replace the keyboard.
10 Re-assemble the oscilloscope.
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