NI SCXI-1127 Relay Replacement

The NI SCXI-1127 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 grounding screw from the back of the module.
   
   

   1 Grounding screw 2 Top cover

3. Carefully remove the top cover of the module using a flathead screwdriver.
4. Remove the two screws from the back of the module.
   
   

   1 Rear screws

5. Locate the relay you want to replace. Refer to the following figures and table for relay locations.
   
   

   

   
   
   

   

   
   
   

   Channel Name	Relay Name
   CH0, CH32	K2
   CH1, CH33	K3
   CH2, CH34	K1
   CH3, CH35	K4
   CH4, CH36	K11
   CH5, CH37	K10
   CH6, CH38	K12
   CH7, CH39	K13
   CH8, CH40	K18
   CH9, CH41	K19
   CH10, CH42	K20
   CH11, CH43	K21
   CH12, CH44	K25
   CH13, CH45	K26
   CH14, CH46	K27
   CH15, CH47	K28
   CH16, CH48	K32
   CH17, CH49	K31
   CH18, CH50	K29
   CH19, CH51	K30
   CH20, CH52	K35
   CH21, CH53	K36
   CH22, CH54	K33
   CH23, CH55	K34
   CH24, CH56	K37
   CH25, CH57	K38
   CH26, CH58	K39
   CH27, CH59	K40
   CH28, CH60	K44
   CH29, CH61	K43
   CH30, CH62	K41
   CH31, CH63	K42
   BC01	K15
   BC02	K14
   BC23	K22
   HI_SELECT	K7
   1WIRE	K6
   4W_HVAB_DISC	K16
   2W_HVAB_DISC	K8
   CJTEMP	K5
   AB0	K9
   AB1	K23
   AB2	K17
   AB3	K24

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.