Capacitors...

is your equipment sounding worse than you recall?

It may well be caps, some psu caps only have a working life of around 2000 hours, I am not sure how many people know this, but if you play it for 2 hrs a day, that's say 10 hrs a week, 50 weeks makes 500 hours per year, that means after 4 years your caps need replacing.

scary thought, how many things are older than that or have had more use?

 

About to embark on cap frenzie in my copland cdp

 

Hmmm, its not as simple as that.

http://www.bhc.co.uk/life.htm

 

Ian, think your find that opertaing life at MAX temp, at idle its different.

 

your right, it is more complex, but what about swithcing on, like a car/jet plane at takeoff, they are more stressed at this time, and will also reduce life, but so will having them on all the time.
I wonder how much older kit has been dismissed, that may just need a few cap changes?

 

Does life not depend on the type of capacitor?

My tech tells me the squillions l have spent on Backgates will not be wasted as they experience next to no degradation in performance over time.

 

there a peice on RS about cap life to precis.....

if rated at 105c and a life of 1000hrs it will last at

105 1000
95 2000
85 4000
75 8000
65 16000

so for every 10 degrees c below max you double the life

 

Reducing the stress, voltage, ripple current or temp, will all increase life or put another way over specifying the device for the intended application will increase life. The above figures are somewhat misleading, as they are for max. operating conditions. A cap that needs replacing after 4 years probably means its not suited for the application.

 

sorry......... that was the whole point

normal application you will get extended life expectancey.......sorry I thought that was obvious.

 

An electrolytic that is used way below its voltage rating, say 1/3 max [unusual scenario, I accept] would probably have an increase in leakage current [trivially small until it becomes very sick] and an increase in capacitance over time, as the dielectric thins, and any electrolytic will have a gradual increase in resistance as it 'dries out'