T&T: Repair vs. replace

[LRZeitlin at aol.com]

In a message dated 7/3/07 12:01:21 AM, Arild writes:


> 
> REPLY
> Probably because equipment back then was actually designed to be repaired.
> 
> We are all being victimized by the cult of mediocrity.
> Because enough people are willing to accept mediocre, slip shod products
> that sort of work, it has becoming nearly impossible to find manufacturers
> who make really good quality products.
> 
> 

It's not a cult of mediocrity per se. Reliability analysis was once one of my 
responsibilities in a moderately long stint in the military-industrial 
complex. Repairability works against reliability. Equipment that is designed to be 
repaired has socketed electrical components and test points. Many functions are 
carried out by discrete components which can be replaced individually. 
Mechanical parts are secured by screws or bolts and cases are designed to be taken 
apart. All are potential sources of failure. 

Equipment designed for reliability has electrical parts soldered in place, no 
sockets. Integrated circuitry tends to be used instead of individual 
components. Mechanical components are spot welded in position or otherwised secured so 
that they can't be removed. Cases are sealed, often glued or welded shut. It 
is also cheaper to make this type of device on an automated production line.

Although the first type of equipment can be repaired quickly, its MTBF is 
often much shorter. The two different classes of equipment give rise to different 
maintenance philosophies. To fix the repairable stuff, you need tools and a 
supply of spair parts plus trained technicians who know how to fix it when it 
breaks. The repair pholosophy for the second type of component is simple 
replaicement of the failed module. No repair is attempted. Often it is impossible. 
Obviously the requirement for technical skills on the part of the repairman are 
much lower. However, you do need a big inventory of replacement modules. The 
military leans toward the second method. 

As fewer and fewer young people choose to become repair persons and/or 
maintenance technicians, industry tends to lean toward the replace rather than 
repair philosophy. It is often cheaper and quicker to throw away the old unit and 
substitute a new one rather than attempt a repair. Try to fix the 
microprocessor on an electrically controlled diesel. Have you had your car repaired 
recently? What did they do?

Larry Z 


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