NI SCXI-1000 SCXI Chassis User Manual

3. Using a pair of needle-nose pliers, carefully extract the fuse.

4. Take a new fuse and bend its leads so the component is 12.7 mm (0.5 in.) long, the dimension between the fuse sockets, and clip the leads to a length of 6.4 mm (0.25 in.).

5. Using the needle-nose pliers, insert the fuse into the socket holes.

6. Repeat for the other fuse if necessary.

7. Check the fan filter and, if it is dirty, clean it as described in the Maintaining the Fan Filter section.

8. Reinstall the fan and filter

Replacing the Fuses on the SCXI-1000DC

There are two fuses located on the rear panel of the SCXI-1000DC. The input power fuse (F1) is a 6.3 A, 5 × 20 mm time-lag fuse. The internal +5 VDC supply is fused by a 3.15 A, 5 × 20 mm time-lag fuse (F2).

Replacing the Power Entry Fuse and +5 VDC Fuse

Caution For continued protection against fire, replace fuses only with fuses of the same type and rating.

Complete the following steps to replace the rear panel fuses: 

 1. Power off the chassis. 

 2. Remove the power cord from power entry connector J1. 

 3. Turn the fuse holder counter-clockwise with a screwdriver and pull out the fuse holder to expose the fuse in the housing. 

 4. Remove the fuse. 

 5. Install the new fuse. 

 6. Push the fuse holder back into the housing and screw it clockwise until it is secure. 

 7. Reinsert the power cord.

Replacing and Checking Backplane Fuses

In addition to the power entry and the +5 V supply fuses, the analog supply lines on the backplane are fused at 1.5 A on the SCXI-1000DC chassis. If you design a special/prototype module, use the SCXI-1181 module and fuse the module at 250 mA to avoid blowing the analog backplane and +5 V supply fuses. Fusing the module better protects the module when a failure results in a large amount of current drawn by not allowing the current to blow the backplane fuses and +5 V fuses. On the SCXI-1000DC, the backplane fuses are located behind the fan. Complete the following steps to check or replace fuses: 

 1. Remove the appropriate fan and filter from the rear of the chassis by following the instructions in the Maintaining the Fan Filter section. Be sure to switch the power off and remove the power cord. 

 2. The fuse marked with a copper + on the backplane is for the positive analog supply, and the fuse marked with a copper – is for the negative analog supply. To check whether a fuse is blown, connect an ohmmeter across the leads. If the reading is not approximately 0 Ω, replace the fuse. 

 3. Using a pair of needle-nose pliers, carefully extract the fuse. 

 4. Take a new fuse and bend its leads so the component is 12.7 mm (0.5 in.) long, the dimension between the fuse sockets, and clip the leads to a length of 6.4 mm (0.25 in.). 

 5. Using the needle-nose pliers, insert the fuse into the socket holes. 

 6. Repeat, if necessary, for the other fuse. 

 7. Check the fan filter and, if it is dirty, clean it as described in the Maintaining the Fan Filter section. 

 8. Reinstall the fan and filter.