Tektronix WFM5250, Service Manual

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Troubleshooting
HDMI Input Checks This procedure requires disassembly. It should be performed only if the HDMI
input fails to perform correctly.
1. Follow the steps to remove the FPGA board. (See page 30, FPGA board .)
2. With the FPGA board removed, power up the instrument.
3. Plug in an HDMI cable, driven by any HDMI signal, into input HDMI 2A.
4. Verify that the red LED labeled HDMI Input A turns on. (See Figure 2.) If
it does not turn on, replace the Video I/O Board.
5. Move the HDMI cable to input HDMI 2B.
6. Verify that the red LED labeled HDMI Input B turns on. If it does not turn on,
replace the Video I/O board.
7. If both LEDs function correctly when an input is plugged in, the failure is
probably in the parallel video bus that connects the Video I/O board to the
FPGA board. This could be on the FPGA board or the Video I/O board.
Basic Power Supply Fault
Checks
This procedure requires disassembly. It should be performed only if the unit fails
to operate to the point where diagnostics can be run, and if the power button is
continuously lit red. The power button is normally red for about 2 seconds when
the unit is
fi rst powered up. In addition, the power button may be red in the case
of any detected hardware fault. To isolate the symptom to a power supply fault, it
is necessary to view the fault LEDs on the Video I/O board.
Remove the carrying case, if present, to gain viewing access to the Video I/O
board fault LEDs DS2, DS3, DS4 and DS5, located on the right edge of the
Video I/O board. These are visible through the lower right side ventilation holes.
Connect power and press and hold the power button. If none of the four fault
LEDs is red, exit this procedure.
LEDs DS1, and DS3 indicate faults on the Video I/O board. If any one of them is
red, replace the Video I/O board. If either DS4 or DS5 is lit, then isolate the faulty
assembly by removing them one at a time in the order listed below. Disconnect
the power before removing each assembly and reconnect power and press the
power button to test. The
fi rst board or cable to be removed that causes a Video
I/O board fault LED to stop lighting is probably faulty and should be replaced.
1. Reference I/O cable at FPGA board J4
2. LCD cable at FPGA board J7
3. FPGA board
4. Display backlight cable at CPU board J5 (remove Video I/O board to gain
access, then reinstall Video I/O board)
For the next two steps, test by pressing Video I/O board switch S1 instead of the
(disconnected) front panel power button.
WFM5250 Waveform Monitor Service Manual 21