We have one 3070 out of 3 that keeps blowing the +20V bus fuse on the ASRU card. A few months ago, the fuse was blowing constantly. Keysight support suggested replacing the ASTEK MPU resistor in the wire harness. After replacing the fuse with the correct value, this kept the fuse from blowing for a few months, but it just blew again today. I replaced the fuse and it blew again immediately.
The indication of the fuse blown is the auto adjust all needs to run box pops up on the operator screen and reports an infinite value temperature (-115 degrees C). Runing diagnostics is useless because the ASRU measurements are off the charts without the fuse.
Does anyone know any other reason this fuse would blow?
The indication of the fuse blown is the auto adjust all needs to run box pops up on the operator screen and reports an infinite value temperature (-115 degrees C). Runing diagnostics is useless because the ASRU measurements are off the charts without the fuse.
Does anyone know any other reason this fuse would blow?
Solved!
It turned out to be the Astec supply enable line pull up resistor.
Solution: The original resistor is 39 ohms. It should be 68 ohms. The resistor is inline in the wire harness of the MPU. Replacing the power supply includes the wrong value resistor.