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Chip Amps Amplifiers based on integrated circuits

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Old 27th May 2012, 10:49 AM   #4011
AndrewT is online now AndrewT  Scotland
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A new cap is effectively one that has been freshly reformed. This applies irrespective of whether it was manufactured yesterday, or last week, or last month, or a year ago. If it has been on the shelf and/or in transit for longer than 24hrs, then it must be reformed immediately before testing/measuring.

Once you compare a freshly reformed "in spec" cap to a 100hrs in operating mode also "in spec" you should find that there is no difference.

If you pick an "off the shelf" cap that is leaking "out of spec" because the insulation has degraded, then it almost certainly will be different. It is "out of spec" and by definition it is different.
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Old 27th May 2012, 11:41 AM   #4012
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And freshly reformed X and Y caps will not change after 100hrs of operation?
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Old 27th May 2012, 12:42 PM   #4013
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I am referring to the electrolytics that must be reformed.
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Example : effective resistance at the 100uF's+supply of 0.1R, some 50nH inductance from wiring,
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Old 27th May 2012, 01:00 PM   #4014
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Did a search on this subject, very interesting. So it seems like a bad idea to switch any equipment off because probably all circuits have electrolytics somewhere.

I am also interested whether this applies to the newer solid state electrolytic devices or not?
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Old 27th May 2012, 02:23 PM   #4015
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Quote:
Originally Posted by soongsc View Post
Do you see much variation between a new cap versus after 100hrs or more run in?
No, as the series inductance (ESL) of any cap is only dependent on its geometry, caps from the same maker which have the same dimension (can size and lead spacing) have identical ESL. ESR is mostly dependant on temperature, though.
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Old 28th May 2012, 11:52 PM   #4016
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Quote:
Originally Posted by soongsc View Post
And freshly reformed X and Y caps will not change after 100hrs of operation?
An old thread about X and Y caps.

X2, AC Line Capacitors
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Old 29th May 2012, 03:03 AM   #4017
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Thanks Kevin. I notice change in sound after 100hrs of operation, but the change is really small. This caps are often used to prevent noise from coupling into the mains power line and making an antenna out of those lines. Interesting to see people reporting change in value to the tolerance limits in as little as 1000hrs.
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Old 29th May 2012, 10:02 AM   #4018
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Originally Posted by soongsc View Post
.............Interesting to see people reporting change in value to the tolerance limits...........
Where?
In the X2 link?
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Old 29th May 2012, 11:53 AM   #4019
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Yes. In the linked thread that Kevin provided mentioned 10% in 1000hrs.
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Old 29th May 2012, 12:05 PM   #4020
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X & Y capacitors are self healing. That is one of the basic characteristics that allow them to be used on the Primary side.

As a result of self healing any transient that "burns out" a section of the capacitor must become a non capacitor area.
Each overloading transient will reduce the area of the capacitor's plates.

It is a natural consequence of overloading a self healing X or Y capacitor that the capacitance will reduce.

The worse and/or more frequent the overloading the quicker that the X or Y cap will lose capacitance.

If you read the X, Y cap info you will find all that information either directly or by inference.

Learn to read.
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