Power supply caps

[C Moore]

So I am replacing the plug on my daughters stereo, and I have it opened up. It is 8 years old and seems to work fine. Would I be throwing money away if I spent 20 dollars and replaced the E-Caps in the power supply?
Is it likely the caps would last another 8 years without trouble?
Thank You

[martin manning]

If they look like that plug, yes! Seriously, I doubt they are in a deteriorated state, and will likely last many more years.

[CHIP]

Is it a myth that E-caps should be replaced about every 10 years?

[martin manning]

Is it a myth that E-caps should be replaced about every 10 years?

It depends... From R.G. Keen's excellent web site http://www.geofex.com/tubeampfaq/taffram.htm :

"If the capacitor is used regularly, has voltage applied to it, and does not get too hot, the oxide film lasts up to a few decades. If the capacitor is not used much, or gets too hot, the oxide film slowly un-forms, the leakage current goes up, and it will eventually short.

Electrolytic caps are designed to last ten years. It is a tribute to the quality of manufacture that they often last three, sometimes four times that.

Old amps, particularly if they have not been used regularly need to have every electrolytic cap replaced. This cap job may be needed every ten or so years."

[guitarmike2107]

Electrolytic caps are designed to last ten years. It is a tribute to the quality of manufacture that they often last three, sometimes four times that.

Actually all Electrolytic caps have a rated life expectancy, you need to check the data sheets, Generally your standard duty cap is rated at 2000 hrs at a specific operating temperature, normally 85 – 105 Celsius.
As a rule of thumb, the life doubles for each 10°C lower operating temperature. So if they are in a cool environment they will last much longer.

Your higher quality caps are often rated at 5000 – 10000 hours at a specific temperature. Normally 105 degrees

Now the thing with modern hi-fi’s is that if you use the standby function instead of turning them off those caps may be working all the time, you can easily check this, if they are and you really like the hi-fi then changing them while your in there is easy enough to do and wont hurt it.

HTH