I do not recommend changing points capacitors and would like to solicit
comments to see if people agree/disagree with me.
Explanation:
Most electronic devices exhibit a 'bathtub' failure characteristic.
THis can be explained in 3 phases:
1. Infant Mortality. Devices exhibit a high failure rate initially.
Probably due to manufacturing defects which do not show up on test.
THis initial rate declines over time until one reaches the second
stage.
2. Normal operating life. Random failures. Components exhibit a
low level of random failures. This is measured as the MTBF (mean
time between failures). This low rate continues for the component's
operating life until it reaches the final stage:
3. End of life. The components wear out and failure rates increase again as
the devices age.
Now the key question is how long are these stages? I have never changed a
capacitor and have never had one fail. Conversely, I have read of many
people on this list who put in new capacitors and had them fail very
quickly. However, when do end-of-life failures occur?
One posting suggested that they can last at least 30 or so years. Can anyone
provide any data points on how long capacitors which get through the infant
mortality stage actually last?
I suggest that, if you replace capacitors on a routine basis, you will
constantly run the risk of an early failure, whereas, if you leave it there
for 10-20 years, your risk of failure will be less.
Arguments, anyone? Facts and data welcome.
Simon
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