failure of I/P caps

hkivan · 05-25-2006, 04:45 PM

Hello guys,

1) How do I know the 2 bulky I/P caps failure?
I have a DMM & a cap meter but no ESR meter.
I checked all my caps. They are more or less within spec.

2) Will they burst or bulge just like those low volts?

3) What will happen if they fail & will they render my
PSU non-repairable ?

Thank in advance and any comments are welcome !

japlytic · 05-25-2006, 07:16 PM

1) The two bulky input capactors are normally 200V or 250V, and the size of them depends on the wattage of the unit.

2) They normally fail through excessive ripple current (especially if they are under-rated for the wattage of the supply), or if the voltage selector switch is in the "110-120" position when connected to a 220-240V socket.

3) When they fail, the fuse would blow, and in very few cases, take the bridge rectifier (and possibly the NTC or input surge limiting resistor) with them. Generally, no other components in the supply would be damaged.

PeteS in CA · 05-25-2006, 09:39 PM

If the P/S is set for "110-120" and plugged in to 220-240, the MOVs are likely to fry also. They may protect the I/P lytics from damage, but I would still replace the caps.

hkivan · 05-25-2006, 09:44 PM

1) not answered
2) not answered
3) thanks, good answer

japlytic : Queensland is a beautiful place where I wish to go,
especially the famous Great Barrier Reef .
My last visit to au was to sydney. The bondi beach, blue mountains, Wollongong, Canberra, many places are good to remember. It took me less than 4 hrs to drive from Canberra to Sydney via M5 but it took a long time
via Prince highway. But there are many beaches worth to visit along the coast.
Surely, I will go to the Reef on my next visit to au !

05-25-2006, 04:45 PM	#1
hkivan Senior Member Join Date: Mar 2006 City & State: Hong Kong Posts: 120	failure of I/P caps Hello guys, 1) How do I know the 2 bulky I/P caps failure? I have a DMM & a cap meter but no ESR meter. I checked all my caps. They are more or less within spec. 2) Will they burst or bulge just like those low volts? 3) What will happen if they fail & will they render my PSU non-repairable ? Thank in advance and any comments are welcome !

05-25-2006, 07:16 PM	#2
japlytic Badcaps Veteran Join Date: Oct 2005 City & State: Rockhampton, Queensland, Australia My Country: Australia Line Voltage: 240VAC 50Hz I'm a: Hobbyist Posts: 1,299	Re: failure of I/P caps 1) The two bulky input capactors are normally 200V or 250V, and the size of them depends on the wattage of the unit. 2) They normally fail through excessive ripple current (especially if they are under-rated for the wattage of the supply), or if the voltage selector switch is in the "110-120" position when connected to a 220-240V socket. 3) When they fail, the fuse would blow, and in very few cases, take the bridge rectifier (and possibly the NTC or input surge limiting resistor) with them. Generally, no other components in the supply would be damaged. __________________ My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.

05-25-2006, 09:39 PM	#3
PeteS in CA Badcaps Veteran Join Date: Aug 2005 City & State: San Jose, CA My Country: USA, Unsure of Planet Line Voltage: 120VAC, 60Hz & 115VAC, 400Hz I'm a: Professional Tech Posts: 1,588	Re: failure of I/P caps If the P/S is set for "110-120" and plugged in to 220-240, the MOVs are likely to fry also. They may protect the I/P lytics from damage, but I would still replace the caps. __________________ PeteS in CA Republican Operative discussion forums Where might is right There is no right. - Sophocles in "Antigone" ************************** All that is gold does not glitter, Not all those who wander are lost; - J.R.R. Tolkien, The Fellowship of the Ring ************************** To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.

05-25-2006, 09:44 PM	#4
hkivan Senior Member Join Date: Mar 2006 City & State: Hong Kong Posts: 120	Re: failure of I/P caps 1) not answered 2) not answered 3) thanks, good answer japlytic : Queensland is a beautiful place where I wish to go, especially the famous Great Barrier Reef . My last visit to au was to sydney. The bondi beach, blue mountains, Wollongong, Canberra, many places are good to remember. It took me less than 4 hrs to drive from Canberra to Sydney via M5 but it took a long time via Prince highway. But there are many beaches worth to visit along the coast. Surely, I will go to the Reef on my next visit to au !

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