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    Checking the FPC fuses


    To isolate an FPC failure by checking the FPC fuses.


    The M40e and M160 router fuses are located in a fuse box at the rear of the midplane, behind the lower rear impeller assembly. You must remove the lower impeller assembly to access the fuses, as described in the appropriate hardware guide.

    The M320 router requires fuses for the FPCs. The fuses for the and FPCs are located in the rear of the midplane behind the power supply in slot PEM0.

    When the fuse for an FPC blows, the FPC stops functioning even though it is installed correctly and the power supplies are providing power to the router.

    For the M40e and M160 routers, when a fuse has blown but the power supplies are still delivering power to router, the amber LED adjacent to the fuse lights. For vertically oriented fuses (in the groups labeled J241 through J244).

    Another indication that a fuse has blown is when the colored indicator bulb inside it becomes visible through the clear cover on the fuse. For information about the indicator bulb color for each fuse type, see the appropriate router hardware guide.

    A blown fuse can cause a component to fail even though it is correctly installed and the power supplies are functioning. Check for a blown fuse in the following circumstances:

    • The LED that indicates normal operation for the component fails to light.
    • The appropriate show chassis environment command indicates that the component is installed but is not receiving power.

    Figure 1 shows the location of the M320 fuses in the rear of the midplane for the FPC. (The labels shown in the figure do not appear on the actual fuses—the clear cover on every fuse reads BUSS GMT-X—and might not match the labels on the midplane. Ignore the labels on the midplane.)

    Figure 1: Component Fuses in the M320 Router Midplane

Fuses in the M320 Router Midplane

    Published: 2012-08-20