NI SCXI-1175 Relay Replacement

The NI SCXI-1175 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 rear screws from the back of the module.
   
   

   1 Rear screws 2 Top cover 3 Rear panel

3. Carefully remove the top cover of the module using a flathead screwdriver.
   
   
4. Remove the rear panel.
   
   
5. Remove the hex standoffs from the front of the module.
   
   

   1 Hex standoffs

6. Slide the relay assembly out of the enclosure.
   
   

   1 Relay assembly 2 Enclosure

7. Remove the four screws that secure the mezzanine board to the base board.
   
   

   1 Screws 2 Mezzanine board 3 Base board

8. Separate the mezzanine board from the base board.
   
   
9. Locate the relay you want to replace. Refer to the following figures and table for relay locations.

   Base Board

   Mezzanine Board

   
   

   1-Wire 196×1 Channel Name		2-Wire 95×1 Channel Name	2-Wire 98×1 Channel Name	Relay Name
   CH0	CH95	CH0	CH0	K97
   CH1	CH96	CH1	CH1	K93
   CH2	CH97	CH2	CH2	K89
   CH3	CH98	CH3	CH3	K85
   CH4	CH99	CH4	CH4	K81
   CH5	CH100	CH5	CH5	K77
   CH6	CH101	CH6	CH6	K73
   CH7	CH102	CH7	CH7	K69
   CH8	CH103	CH8	CH8	K65
   CH9	CH104	CH9	CH9	K61
   CH10	CH105	CH10	CH10	K57
   CH11	CH106	CH11	CH11	K53
   CH12	CH107	CH12	CH12	K47
   CH13	CH108	CH13	CH13	K44
   CH14	CH109	CH14	CH14	K40
   CH15	CH110	CH15	CH15	K39
   CH16	CH111	CH16	CH16	K32
   CH17	CH112	CH17	CH17	K28
   CH18	CH113	CH18	CH18	K24
   CH19	CH114	CH19	CH19	K20
   CH20	CH115	CH20	CH20	K16
   CH21	CH116	CH21	CH21	K11
   CH22	CH117	CH22	CH22	K7
   CH23	CH118	CH23	CH23	K3
   CH24	CH119	CH24	CH24	K52
   CH25	CH120	CH25	CH25	K56
   CH26	CH121	CH26	CH26	K60
   CH27	CH122	CH27	CH27	K64
   CH28	CH123	CH28	CH28	K68
   CH29	CH124	CH29	CH29	K72
   CH30	CH125	CH30	CH30	K76
   CH31	CH126	CH31	CH31	K80
   CH32	CH127	CH32	CH32	K84
   CH33	CH128	CH33	CH33	K87
   CH34	CH129	CH34	CH34	K91
   CH35	CH130	CH35	CH35	K95
   CH36	CH131	CH36	CH36	K2
   CH37	CH132	CH37	CH37	K6
   CH38	CH133	CH38	CH38	K10
   CH39	CH134	CH39	CH39	K14
   CH40	CH135	CH40	CH40	K19
   CH41	CH136	CH41	CH41	K23
   CH42	CH137	CH42	CH42	K27
   CH43	CH138	CH43	CH43	K31
   CH44	CH139	CH44	CH44	K35
   CH45	CH140	CH45	CH45	K38
   CH46	CH141	CH46	CH46	K43
   CH47	CH142	CH47	CH47	K46
   CH48	CH143	CH48	CH48	K96
   CH49	CH144	CH49	CH49	K92
   CH50	CH145	CH50	CH50	K88
   CH51	CH146	CH51	CH51	K83
   CH52	CH147	CH52	CH52	K79
   CH53	CH148	CH53	CH53	K75
   CH54	CH149	CH54	CH54	K71
   CH55	CH150	CH55	CH55	K67
   CH56	CH151	CH56	CH56	K63
   CH57	CH152	CH57	CH57	K59
   CH58	CH153	CH58	CH58	K55
   CH59	CH154	CH59	CH59	K51
   CH60	CH155	CH60	CH60	K45
   CH61	CH156	CH61	CH61	K42
   CH62	CH157	CH62	CH62	K37
   CH63	CH158	CH63	CH63	K34
   CH64	CH159	CH64	CH64	K30
   CH65	CH160	CH65	CH65	K26
   CH66	CH161	CH66	CH66	K22
   CH67	CH162	CH67	CH67	K18
   CH68	CH163	CH68	CH68	K13
   CH69	CH164	CH69	CH69	K9
   CH70	CH165	CH70	CH70	K5
   CH71	CH166	CH71	CH71	K1
   CH72	CH167	CH72	CH72	K50
   CH73	CH168	CH73	CH73	K54
   CH74	CH169	CH74	CH74	K58
   CH75	CH170	CH75	CH75	K62
   CH76	CH170	CH76	CH76	K66
   CH77	CH172	CH77	CH77	K70
   CH78	CH173	CH78	CH78	K74
   CH79	CH174	CH79	CH79	K78
   CH80	CH175	CH80	CH80	K82
   CH81	CH176	CH81	CH81	K86
   CH82	CH177	CH82	CH82	K90
   CH83	CH178	CH83	CH83	K94
   CH84	CH179	CH84	CH84	K0
   CH85	CH180	CH85	CH85	K4
   CH86	CH181	CH86	CH86	K8
   CH87	CH182	CH87	CH87	K12
   CH88	CH183	CH88	CH88	K17
   CH89	CH184	CH89	CH89	K21
   CH90	CH185	CH90	CH90	K25
   CH91	CH186	CH91	CH91	K29
   CH92	CH187	CH92	CH92	K33
   CH93	CH188	CH93	CH93	K36
   CH94	CH189	CH94	CH94	K41
   CH190	CH193	—	CH95	K48
   CH191	CH194	—	CH96	K49
   CH192	CH195	—	CH97	K98
   COM Relay				K15
   —		HVAB Relay		K99

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.

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.