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                           IBM ECA
              Engineering Change Announcement

Parts removed from this machine and returned to IBM must be genuine,
                      unaltered IBM Parts

         IBM World Trade Corporation, CE Department Germany
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 EC NUMBER         :  ECC99401     DATE             : 92-06-25
 MANDATORY         :  N
 AUTOMATIC SHIPMENT:  N            SERVICE CODE     : 33
 PARTS SOURCE      :  YASU         AVAILABILITY DATE: 92/05
                                                                                
 PURPOSE: To prevent the following problems on PS/55 Model                      
          5551-V0/V1.                                                           
 -"POST ERROR" at power on time(POST 10482,602)                                 
 -"SYSTEM HUNG" or "SYSTEM EXCEPTION" problem at system running.                
   (exclude S/W bug)                                                            
                                                                                

 Type             Machines Affected                             
 Mod.  With       and/or Feature/Device    B/M to be  Serv Syst 
 Stg.  B/M        Description              Installed  Hour Hour 

 Plant 97                                                       

 5551- B/M0005551 S/N RANGE                B/M06G7000 01.0 01.0 
   V0A B/M0005551    97QXXXX --> 97SXXXX   B/M06G7000 01.0 01.0 
   V0B B/M0005551    97WXXXX --> 97YXXXX   B/M06G7000 01.0 01.0 
   V1A B/M0005551    97MAXXX --> 97NZXXX   B/M06G7000 01.0 01.0 
   V1B B/M0005551    97PAXXX --> 97PZXXX   B/M06G7000 01.0 01.0 
   V1A               97MAXXX --> 97NZXXX                        

                                                                                
 PHYSICAL CHECK:                                                                
 Check EC number of System Board P/N 23F2146.                                   
 If EC number is 341631A through 341631V, Install this FBM.                     
                                                                                
 PREREQUISITES: NONE                                                            
                                                                                
 COMPANION: NONE                                                                
                                                                                
 CONCURRENT: NONE                                                               
                                                                                
 DETAIL:                                                                        
 Replace Delay line module on the System Board.                                 
 To replace the Delay Line Module, you may need special tools.                  
 Contact with WSSC support member. (TEL 0462-73-4566)                           
 NOTES:                                                                         
 This FBM is available until the end of February in 1993.                       
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