Technical data

User’s and Service Guide 63
87050A Option K22 Troubleshooting and Block Diagram
Troubleshooting and Block Diagram
This section contains information on troubleshooting the test set to assembly level only.
Following these procedures should enable you to determine whether the power supply,
front panel, or main switch board need replacing. A block diagram is included at the end of
this section as an aid in troubleshooting.
Theory of operation information can be found in the next section of this manual.
General Troubleshooting Notes
WARNING Always turn the instrument power off before removing or
installing an assembly.
CAUTION 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).
Power Supply Problems
Turn the instrument on. Verify the condition of the LCD on the front panel:
• If it is off, there is still a possibility that the power supply is not supplying the
necessary +24V, +12V, and +5V to the main board.
• If the LCD is off, check the main fuse located in the power supply filter at the rear of
the instrument.
• If the LCD is still off, check the cable between the main board and front panel board.
• Finally, disconnect the DC power cable from the power supply to the main switch
board and measure the voltages. They should be +15V, +12V, and +5V. If not, replace
the power supply.