Troubleshooting 4
5000 Series Oscilloscopes Service Guide 71
4 If any of the test point voltages are not within the specified
range, replace the AC input board.
To check the system board
1 Disconnect J2730 from the system board and measure pins
19 and 20 on the J2730 connector. This is the voltage to the
display, and it should be +3.3 V. If it is not, replace the system
board. If the voltage is correct, replace the display.
2 Disconnect J2750 from the system board and measure pins 3
and 4 on the J2750 connector. This is the voltage to the
inverter, and it should be +5 V. If it is not, replace the system
board. If the voltage is correct, replace the display.
3 If all cables are properly connected and none of the previous
tests confirm a failure on another assembly, replace the
system board.
To check the display
1 Disconnect the power cord.
2 Check to verify that the backlight inverter cable is connected.
3 Ensure the display LCD cable is connected.
4 Connect the power cord.
5 Use the DMM to check the Inverter Power voltage (see table
below).
6 If the voltage is incorrect, replace the system board.
7 If the voltage is correct, use an oscilloscope to check the LCD
clock (see table below).
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