Mso Assembly Troubleshooting - Keysight 90000 X Series Service Manual

MSO Assembly Troubleshooting

This section describes problems that may occur when an MSO assembly is installed,
and how to troubleshoot them. The MSO printed circuit assembly is located below the
lower acquisition board, with the components facing downward.
LEDs on MSO Assemblies
The MSO printed circuit board has two sets of LEDs. One set is visible from the right
side of the oscilloscope, and the other set is visible from the left side.
MSO LEDs on the right side of the oscilloscope
To see the LEDs on the right side, look straight in through the vent holes and see the
lights pointed toward the bottom of the oscilloscope. These two red LEDs turn on when
the oscilloscope is turned on, indicating that the comparators are off. The LEDs stay
on until the FPGA is programmed by the scope application software; then the software
turns the LEDs off when it turns the comparators on.
If the LEDs turn on after the application is running, a thermal problem likely was
detected. A warning appears. To resolve the problem, shut down the scope and allow
it to cool. Make sure the fan holes are not blocked, and allow at least 4 inches of space
next to the oscilloscope. Restart the scope and verify that all fans are working.
MSO LEDs on the left side of the oscilloscope
The LEDs on the left side can be seen only as a reflection in the lower sheet metal as
you look through the fans. These LEDs are off until the FPGA is programmed successfully,
which occurs shortly after the scope application starts.
One of the LEDs turns on and remains on after the FPGA is programmed. The other
LED will start blinking steadily at about 1.6 Hz if the 250 MHz clock coming from the
backplane board is working properly. If the LED is not blinking steadily, verify that
the backplane board has been modified correctly to be used with the MSO board:
• The end tabs of connector J1102 should be trimmed down so the mating connector
• In the clock area on the top side of the backplane board, R352 and R353 should be
• If the backplane board part number is 54916- 66402 and the raw board rev number
MSO Cable Connection
The MSO cable must be oriented as shown on the back of the oscilloscope when it is
connected. If it is oriented upside- down, the pins may bend and cause a faulty
connection. Make sure the cable is connected properly and that the pins remain straight.
Refer to Figure 4- 20.
on the MSO board will connect properly.
loaded with 0 ohm resistors. The same area on the bottom side of the board should
not have resistors on R330 and R332. If this clock rework has not been done, the
scope application will display an error message indicating an option card DAC failure
when the application starts up.
is less than 006, the board is unusable and must be replaced.
Chapter 4: Troubleshooting
MSO Assembly Troubleshooting
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