Keysight Technologies Infiniium 90000A Series, Service Manual

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74 90000 A-Series Service Guide
4
Troubleshooting
Keyboard Troubleshooting
Use this procedure only if you encounter key failures in the keyboard self 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.
3
Remove the 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. Re-attach the partial assembly to the chassis.
4
Be sure to reconnect the display video cable and the backlight inverter cables.
See chapter 5 for instructions on removing and disassembling the front panel.
5
Separate the elastomeric keypads from the keyboard assembly.
6
Set the keyboard assembly on an antistatic electrical insulated surface.
7
Connect the keyboard cable to the scope 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.
8
Reconnect the power cable and apply power.
9
Enable the user interface, then start the keyboard test as described earlier in
this chapter.
10
Carefully short the PC board trace with a paper clip or screwdriver, at each
non-operating 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.
11
Re-assemble the oscilloscope.
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.