NI SCXI-1190 Relay Replacement

The NI SCXI-1190 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 and replace a failed relay.

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 five screws that secure the metal shield.
   
   

   1 Screws 2 Metal shield

3. Carefully remove the six nuts that secure the four relay pods to the motherboard.
   
   

   1 Nuts 2 Relay pods 3 Motherboard 4 Ribbon cable connectors

4. Disconnect the four ribbon cable connectors from the motherboard headers by carefully pulling apart the connector locking clips.
   
   

   Caution  Overextending the connector locking clips may cause them to break.

   1 Connector locking clips

5. Separate the relay pods from the motherboard.
   
   
6. To separate an individual pod for relay replacement, remove the three screws as well as the SMB nuts and washers that secure the relay pod to the front panel. Retain the plastic spacers for reassembly.
   
   

   1 Screws 2 Nuts 3 SMB nuts 4 Washers 5 Plastic spacers

7. To remove the shield and relay from the pod, refer to Replace the Relay.
   
   

Replace the Relay

Make sure you have the following:

• 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.

Note  Use a torque wrench set at 2 in-lb to secure the SMB nuts.