System-board  external  connectors 
The  following  illustration  shows  the  external  input/output  connectors  and  the  NMI 
switch  on  the  system  board. 
Mouse
Keyboard
Serial 1
(COM 1)
VGA
LPT
Serial 2
(COM 2)
USB 4
RJ45
RJ45
NMI
USB 3
 
 
Light  path  diagnostics  panel 
The  following  illustration  shows  the  remind  button  and  the  LEDs  on  the  light  path 
diagnostics  panel.  The  light  path  diagnostics  panel  is  inside  the  server  under  the 
left-side  cover  and  the  error  LEDs  are  also  visible  through  the  left-side  cover. 
CPU
VRMS_ERR
MEMORY
DASD/
RAID
NMI
SP BUS
FAN
POWER
SUPPLY
PCI
BUS
2
1
CONFIG
TEMP
REMIND
SEE INSIDE COVER FOR MORE SERVICE INFORMATION
 
 
Use  the  remind  button  on  the  light  path  diagnostic  panel  to  acknowledge  that  an 
error  has  occurred  without  taking  further  action.  When  you  push  the  remind  button, 
the  system  error  LED  will  flash  every  2  seconds  until  the  error  is  fixed.  If  another 
error  occurs,  the  system  error  LED  will  then  stop  flashing  and  return  to  a  solid  on 
state. 
For  more  information  about  light  path  diagnostics,  see  the  Problem  Determination 
and  Service  Guide  on  the  IBM  System  x  Documentation  CD. 
The  following  table  lists  the  light  path  diagnostics  LEDs,  the  problems  that  they 
indicate,  and  actions  to  solve  the  problems. 
 
16  IBM  System  x3500  Type  7977:  User’s  Guide