H095558 - SURGE SUPPRESSORS AND INTERMITTENT PROBLEMS                          
                                                                                
                                                                                
 TEXT:                                                                          
 THERE IS NO REQUIREMENT FOR EXTERNAL SURGE SUPPRESSION DEVICES                 
 ON IBM PC (PERSONAL COMPUTER) OR PERSONAL SYSTEM/2 PRODUCTS.                   
 THE POWER SUPPLIES IN THESE SYSTEMS HAVE BEEN DESIGNED TO MEET                 
 IBM CORPORATE REQUIREMENTS THAT INCLUDE FACTORS CONSIDERED                     
 ADEQUATE FOR PRODUCT PROTECTION.                                               
                                                                                
 IF INTERMITTENT PROBLEMS ARE BEING EXPERIENCED, AND NORMAL                     
 TROUBLESHOOTING EFFORTS HAVE FAILED TO ISOLATE THE SOURCE OF THE               
 PROBLEM, AND AN EXTERNAL "SURGE SUPRESSION DEVICE" IS BEING                    
 USED, TRY RUNNING THE SYSTEM WITHOUT IT.  IF THE PROBLEMS NO                   
 LONGER OCCUR, SUSPECT THE SURGE SUPPRESSION DEVICE TO BE THE                   
 SOURCE OF THE PROBLEM.                                                         
                                                                                
 SURGE SUPPRESSOR FACTS:                                                        
                                                                                
 1. EXTERNAL SURGE SUPPRESSION DEVICES HAVE BEEN KNOWN TO BE THE                
    SOURCE OF DIFFICULT TO DIAGNOSE SYSTEM PROBLEMS.                            
                                                                                
 2. NO UNIVERSALLY ACCEPTED DESIGN OR PERFORMANCE STANDARDS, SUCH               
    AS IEEE OR ANSI, HAVE BEEN ESTABLISHED FOR THESE DEVICES,                   
    THEREFORE DESIGN AND PERFORMANCE VARY BETWEEN VENDORS, OR                   
    MODELS.                                                                     
                                                                                
 3. THERE IS NO PRACTICAL WAY TO TEST THEM IN THE FIELD.                        
                                                                                
 4. RECENT RESEARCH REVEALS SURGE PROTECTORS MAY CONTRIBUTE TO                  
    LAN CRASHES BY DIVERTING SURGE PULSES TO GROUND, THEREBY                    
    CONTAMINATING THE REFERENCE USED BY DATA CABLING.                           
                                                                                
 THERE ARE SEVERAL SURGE SUPPRESSION DEVICES AVAILABLE ON THE                   
 MARKET, HOWEVER THE MOST COMMONLY ENCOUNTERED DEVICE IS THE MOV                
 (METAL OXIDE VARISTOR).  MOV'S HAVE A FAILURE MODE OF "SHORTING"               
 WHEN SUBJECTED TO SURGES BEYOND THEIR PEAK RATINGS, AND ARE                    
 SUBJECT TO "MOV DEGRADATION" OVER TIME, WHICH REDUCES THEIR                    
 VALUE AS SURGE SUPPRESSORS.                                                    
                                                                                
 SAS KEYWORDS:                                                                  
    PSY2               PSY2PWR            PSY2COMM           8525SYSPWR         
    8530SYSPWR         8535SYSPWR         8540SYSPWR         8550SYSPWR         
    8555SYSPWR         8557SYSPWR         8560SYSPWR         8570SYSPWR         
    8573SYSPWR         8580SYSPWR         8590SYSPWR         8595SYSPWR         
    8525SYSCOMM        8530SYSCOMM        8535SYSCOMM        8540SYSCOMM        
    8550SYSCOMM        8555SYSCOMM        8560SYSCOMM        8565SYSCOMM        
    8570SYSCOMM        8573SYSCOMM        8580SYSCOMM        8590SYSCOMM        
    8595SYSCOMM        D/T8580            D/T8590            D/T8595            
    D/T8525            D/T8530            D/T8535            D/T8540            
    D/T8543            D/T8570            D/T8573            D/T8540            
    D/T8550            D/T8555            D/T8556            D/T8557            
    D/T8560            D/T8565            D/T8570            D/T8573            
    D/T8580            D/T8590            D/T8595            D/T9533            
    D/T9556            D/T9557            D/T9576            D/T9577            
    D/T9585            D/T9590            D/T9595            D/T8600            
    D/T8640            D/T8641            D/T8642            D/T8650            
                                                                                
July 22, 1996