Keysight U3020A User’s and Service Guide
31
I/O Distribution board
The I/O Distribution board provides a passive control signal interface between the controller
module I/O port and the front panel Port LED board.
LED indicator board
This board provides an LED indication of the Port setting in the Test Set. The LED indicator board is
driven by the digital IO of the Test Set.
Troubleshooting
This section contains information for troubleshooting the Test Set to the assembly level only. By
following these procedures, you may determine if the power supply, front panel, or main switch
board needs replacing. Refer to
Front panel instrument state LEDs
If you suspect a problem with the Instrument State or Input Port LEDs, first refer to the status
before proceeding. Note that with only a power cable connected to the rear
panel of the Test Set, the PWR LED = Green and LAN LED = Red.
1
If the green PWR LED is OFF after depressing the front panel button continue with the following
procedure:
a
Remove the top cover of the instrument.
b
Ensure that the ribbon cable and 2-wire connector are properly in place.
c
Measure the DC voltage between the red and black wires. The red wire should measure
approxi12 Vdc.
d
If the +12 Vdc is not present on the red wire, measure the three labeled output power supply
voltages on the controller module at the green connector.
e
If any voltages are not present, the controller module power supply will need to be replaced.
2
If the green PWR LED is 'ON' after depressing the front panel button and the LAN LED is OFF
continue with the following procedure:
a
Remove the top cover of the instrument.
b
Ensure that the ribbon cable and 2-wire connector are properly in place.
c
Measure the DC voltage between the red and black wires. The red wire should measure
approxi12 Vdc.
d
If any voltages are not present, the controller module power supply will need to be replaced.
NOTE
If you need to disassemble the instrument, be sure to work at an antistatic workstation and use a
grounded wrist strap to prevent damage from electrostatic discharge (ESD).
Summary of Contents for U3020AS26
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