Keysight Technologies Infiniium MSOV 084A, Service Manual

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66 Infiniium V-Series Oscilloscopes Service Guide
4
Troubleshooting
If the FP SUPPLY FAIL LED is lit
If the FP SUPPLY FAIL LED is the only one lit, there might be a problem with one of
the supplies that goes to the front panel assembly, or a problem on the front panel
assembly. Unplug the front panel power connector (see cable connector circled
below) and turn the oscilloscope on again. If no other under-voltage indicator
LEDs on the backplane assembly turn on, the fault is on the front panel assembly
and it should be replaced. If either the BP POL FAIL or NEG SUPPLY FAIL LEDs turn
on, then replace the backplane assembly and confirm that the fault goes away
with the front panel power reconnected to the backplane assembly.
If the oscilloscope turns off again and no under-voltage fault indicator LEDs are lit,
the bulk +12 V supply may be defective and may need to be replaced.
Before replacing the supply, be sure to verify the operation of the AC OK and DC
OK signals. The AC OK signal indicates that the applied AC signal is within the
specified input range (TTL high logic level indicates that AC input is good). It is
possible for this signal to indicate that the AC input is not within the requested
range even though it is correct. The DC OK signal indicates whether the main
output from the supply (+12.6 V) is good (TTL high logic level indicates the DC
output is good). It is possible for this output to be false even though the supply
output is correct.
Front panel power cable connector