NI SCXI-1193 Relay Replacement

The NI SCXI-1193 uses electromechanical armature relays.

Refer to the following table for information about ordering replacement relays.

Complete the following sets of steps to disassemble your module, replace a failed relay, and reassemble your module.

Disassemble the Module

1. Ground yourself using a grounding strap or a ground connected to your SCXI Chassis.

   Note  Properly grounding yourself prevents damage to your module from electrostatic discharge.

2. Remove the three screws from the back of the module.
   
   

   1 Rear screws

3. Carefully remove the top cover of the module using a flathead screwdriver.
   
   

   1 Top cover 2 Enclosure

4. Disconnect the SMB cable connector from the motherboard connector.
   
   

   1 SMB cable connector 2 Motherboard connector 3 Grounding strap mounting screws 4 Rear panel 5 Relay assembly 6 Enclosure

5. Remove the ground strap mounting screws.
6. Remove the rear panel.
7. Slide the relay assembly out of the enclosure.
8. Remove the MCX cable between the daughterboard connectors.
   
   

   1 MCX cable 2 Daughterboard connectors

9. Remove the six screws holding the daughterboard to the CMI bracket.
   
   

   1 Daughterboard screws 2 Daughterboard connectors 3 Motherboard connector

10. Lift the flexible flat cable latch on the motherboard connector and remove the daughterboard.
11. Remove the shields from the daughterboard.
    
    

    1 Relay shields 2 Daughterboard 3 Flat cable latch 4 Flat cable

12. Lift the flat cable latch on the daughterboard and pull out the flat cable.
13. Locate the relay you want to replace. Refer to the following figures for relay locations.
    
    

Replace the Relay

Before you begin, make sure you have the following items:

• Temperature-regulated soldering iron set to 300 °C
• 60/40 Lead/Tin solder (flux core)
• Solder wick
• Fine pick
• Isopropyl alcohol
• Cotton swabs

If you have a surface mount rework station, replace the relay as you would any other surface mount part. Otherwise, complete the following steps to replace the relay:

1. Use the soldering iron and solder wick to remove as much solder from the relay pads as possible. Do not leave the soldering iron on any lead for more than 5 seconds.

   Note  If it is necessary to reapply the soldering iron to the pad, allow the connection to cool completely before reapplying the soldering iron.

2. Apply heat to the pads one at a time, and use the pick to gently pry the relay pins from the pads. Make sure that the solder is molten before prying.

   Caution  Using excessive force on a soldered pad can result in lifting the PCB trace and ruining the daughterboard.

3. Remove the relay.
4. Clean the pads with isopropyl alcohol and cotton swabs.
5. Place the new relay on the PCB pads and solder.
6. Remove the excess flux with isopropyl alcohol and cotton swabs.

   Caution  Do not use flux remover to clean the board after relay replacement.

Reassemble the Module

Complete the Disassemble the Module steps in reverse order to reassemble your module.

Tip  In NI-SWITCH 3.1 or later, you can use the Switch Soft Front panel to reset the relay count after you have replaced a failed relay.