Replacing a Fuse on an M40e Router

To replace a fuse (see Figure 1):

Warning: You must power off the router before removing or installing a fuse.

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis. For more information about ESD, see Preventing Electrostatic Discharge Damage to an M Series, MX Series, or T Series Router.
2. Remove the rear lower impeller assembly by loosening the thumbscrew at each corner of the impeller cover and sliding the impeller assembly out of the chassis. For complete instructions, see Removing the M40e Rear Lower Impeller Assembly.
3. Determine which fuse has blown. The yellow LED next to the fuse lights and the indicator bulb becomes visible through the clear cover on the fuse.
4. Power off the router as described in Disconnecting AC Power from the M40e Router or Disconnecting DC Power from the M40e Router.
5. Grasp the blown fuse by the edges and rock it in its slot until it comes loose and disconnects. Rock up and down for a vertically oriented fuse (in the groups labeled J241 through J243 in Figure 1) and side to side for a horizontally oriented fuse (in the group labeled J240). If the cover slips off the fuse, snap the cover back into place and begin again.

   Note: We recommend you use an insulated fuse removal tool to remove fuses.

6. Remove the appropriate spare fuse from the group of fuses labeled J244 in Figure 1. (The labels shown in the figure do not appear on the actual fuses—the clear cover on every fuse reads BUSS GMT-X—but a table on the midplane below the fuse box displays the same information.) Verify that the spare has the same rating and color coding as the fuse it is replacing, as specified in Table 1. To see the indicator bulb and printed rating, look at the fuse from the side.
7. For a vertically oriented fuse, orient the replacement fuse over the slot so that the text on the fuse cover (BUSS GMT-X) reads from bottom to top. For a horizontally oriented fuse, orient the replacement fuse over the slot so that the text on the fuse cover is upside down.
8. Press the new fuse into the slot.
9. Power on the router as described in Connecting AC Power to the M40e Router for AC power orConnecting DC Power to the M40e Router for DC power.
10. Verify that the yellow LED next to the replacement fuse is no longer lit.
11. Reinstall the rear lower impeller by sliding it back into the chassis and tightening the thumbscrew at each corner of the impeller cover. For complete instructions, see Installing the M40e Rear Lower Impeller Assembly.
12. Order new fuses from an electrical supply house to replace the spares in the J244 group. The Cooper Bussman product number for each fuse is GMT-X, where X is the amperage rating. For example, product number GMT-15 is a 15-A fuse, required for an FPC.

Figure 1: Fuse Locations in the Fuse Box