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Old 18th January 2017, 09:09 AM
John Caswell John Caswell is offline
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Join Date: Dec 2005
Location: Wokingham, Berkshire
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Default Re: Longevity of modern passive components

Hi all,
The first thing to bear in mind is that there is this "disease" doing the rounds that pretty well any old equipment needs all the electrolytic capacitors and other changing "cos "Joe Bloggs" says so. I refer you to various other forums.
This is not necessarily so and often causes more problems than it is worth, as something that was working, albeit not too well, is often rendered useless.
Whilst i would be the first to admit that old capacitors should be viewed with suspicion, it doesn't necessarily follow that all old capacitors are in the same boat.
There are certain make of capacitors especially the should be deemed suspect, the Red/Black Plessey type , the Maroon ROE as used in Quad, the dark brown WIMA as used in various German products , the black HUNTS type used in the UK.
Modern products are much more reliable and will probably last the lifetime of the unit, but with elcos the thing to watch out for is temperature, overtemp will cause premature failure. When I am repairing a unit I always try to fit in 105C elcos as i do not know what environment the unit will be in.
Resistors fall into much the same categories, a modern 1/4 watt resistor is very small in comparison to one of 30 yrs ago, so for a given dissipation it will get much hotter possibly reducing reliability, so once again if space allows fit a physically larger resistor, and also bear in mind the limiting voltage placed on resistors.
I always suggest replacing output valves on a yearly to two yearly basis depending on use, but small signal valves seem to last forever.
With modern components i do not think you need to worry too much.

John
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