Agilent Technologies 01664-97005 - Manual (Page 112)

To test the keyboard signals
Refer to chapter 6, "Replacing Assemblies," for instructions to remove covers and assemblies.
W A R N I N G
Hazard voltages exist on the power supply, the CRT, and the CRT driver board. This
procedure is to be performed by service-trained personnel aware of the hazards involved,
such as fire and electrical shock.
1 Turn off the instrument and remove the power cable.
2 Without disconnecting the keyboard cable, follow the keyboard removal procedure
to loosen the keyboard. Leave the keyboard in place in front of the instrument.
3 Reconnect the power cable, install the operating system disk, then turn on the
instrument.
4 Run the Front Panel Test, pressing all of the keys.
5 If a random key is not operating, then go to the next step.
If a group of keys do not work, then check the keyboard voltages and signals.
Keyboard Connector Signals
Pin Signal Pin Signal
1 Keyboard Return 13 Keyboard Scan
2 " 14 "
3 " 15 "
4 " 16 "
5 " 17 "
6 " 18 "
7 " 19 LED
8 " 20 +5 V
9 Keyboard Scan 21 Ground
10 " 22 Knob
11 " 23 Ground
12 " 24 Knob
6 Allow the keyboard assembly to fall forward from the front panel. Separate the
elastomeric keypad and keyboard panel from the PC board.
7 Using a paper clip or screwdriver, short the PC board trace of the non-operating key
and look for an appropriate response on the display.
8 If the display responds as if the key were pressed, replace the elastomeric keypad.
If the display does not respond as if the key were pressed, replace the keyboard.
9 Check the RPG connector.
The RPG connector has a TTL pulse on pins 22 and 24 when the knob is being turned. Pin 20
of the connector is +5 V.
Troubleshooting
To test the keyboard signals
5–24