400A Overheat ??

ct1agi · 25th April 2010, 05:47 PM

Hi everybody:
I recently have replaced the 2 big caps on the 400A PSU with two Epcos caps 22000uF, 100Vdc, 85ºC. They match exactly the same diameter of the original, 64mm (Mallory 10000uF, 75Vdc, 85ºC) and are a bit higher - 105mm vs 80 mm but no problems about it.
Since then the temperature of the heatsink seems to be higher...Even with the bias around 85mV, the temperature is considerably higher.
My concerns ar:
a) - something to do with the ESR of the new cap ??
b) - should I reduce the bias until the recomended temperature (45 / 50 ºC) will be reached ??
Your advice / help will be appreciated.

Nelson Pass · 26th April 2010, 05:15 PM

If they are hotter than 55 deg C, then reducing the bias to
that temperature is probably a good idea.

ct1agi · 26th April 2010, 07:34 PM

Thank you Mr. Pass.
I will do that.

25th April 2010, 05:47 PM	#1
ct1agi diyAudio Member Join Date: Oct 2006	400A Overheat ?? Hi everybody: I recently have replaced the 2 big caps on the 400A PSU with two Epcos caps 22000uF, 100Vdc, 85ºC. They match exactly the same diameter of the original, 64mm (Mallory 10000uF, 75Vdc, 85ºC) and are a bit higher - 105mm vs 80 mm but no problems about it. Since then the temperature of the heatsink seems to be higher...Even with the bias around 85mV, the temperature is considerably higher. My concerns ar: a) - something to do with the ESR of the new cap ?? b) - should I reduce the bias until the recomended temperature (45 / 50 ºC) will be reached ?? Your advice / help will be appreciated.

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26th April 2010, 05:15 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	If they are hotter than 55 deg C, then reducing the bias to that temperature is probably a good idea.

26th April 2010, 07:34 PM	#3
ct1agi diyAudio Member Join Date: Oct 2006	Thank you Mr. Pass. I will do that.

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