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Troubleshooting
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Keysight RP7900 Series Advanced Service Guide
E Isolation microcontroller LED
– Green LED flashing indicates that everything is operating normally.
– Solid green LED on indicates a soft start.
– Solid red LED indicates that a microcontroller error has occurred.
F Isolation board rail voltage LED
– Red LED indicates that 425 V (or 980 V, depending on the model) goes
into the isolation board.
G Regulation board rail voltage LED
– Red LED indicates that 565 V goes into the regulation board.
H Bias board LED
– Red LED indicates that 425 V (or 980 V, depending on the model) and
the Power Good (PG) signal goes into the bias board.
2
Inspect all the flex cables and AWG cables connection and verify that they are
correct. Make sure no connector pins are bent when the boards are installed to
the backplane.
3
Measure the PFC output and ensure that the reading is 425 V for the 3-phase,
208 V models or 980 V for the 3-phase, 480 V models.
4
Make sure there is a 425 V (or 980 V, depending on the model) and a 10 V
Power Good (PG) signal going into the bias board. The bias board powers the
remaining boards.
5
Measure the isolation board output. Ensure that the reading is 565 V.
6
Verify that all biasing voltage from bias boards are correct. Refer to
and
for the biasing voltage test point locations and values.
7
Isolate the defective board(s) by disconnecting the cables connecting the
defective board(s) to the other boards.
– Disconnect the cable from the AC output to the isolation board to verify
that the AC board is functioning properly.
– Disconnect the cable connecting the isolation board to the regulation board
to verify that the isolation is good.
– Disconnect the cable from the regulation board to the output board to
verify that the regulation is good.
