Question Do PSU capacitors age/burst even when a PSU is not being used/unplugged?

[Turbonium]

I have some older rigs that have been in boxes/storage for around 6-7 years now. I also have a few PSUs that have been in storage on their own (one of them being factory sealed, in fact), two of which I'm trying to sell on eBay.

I'm just wondering if any of the PSUs may be an issue; could any of the capacitors (which I understand are the first things to go in a PSU) be on the way out (or already gone)? Or do PSU capacitors only age/burst at significant levels if they're being used?

(I did some quick googling, and it seems the capacitors may indeed be in bad shape - could use some clarification.)

 

[tcsenter]

I had a Corsair CX400 (based on Seasonic S12II internals) just vented/popped two caps yesterday, upon powering it on first time since 2017. I first put it into use same year as a testing station/technician PC, probably used it a grand total of 80 hours before other things took my time away. I found the invoice - 2009! So it was in my closet NIB from 09 to 17, used about 80 hours, then mothballed (in climate controlled closet) until yesterday.

Funny thing is that voltages check out OK with multimeter, but then there is little load on it. I am going to recap it but wondering how long the other caps will last, just from age even though they look fine.

It reminds me of when I had about 15 mobos in storage NIB dating from the mid-2000s, most from the 'bad cap' era circa 2004 ~ 2008. Never used, except to update the BIOS, run some stress tests/benchmarks on CPU and RAM for several hours or overnight, then put back into the boxes. None were premium/enthusiast boards, all of them were for mid-range/budget builds.

Several years ago, I was pruning my hoard of components and went through them, most had bulging or leaking caps especially around the VRM, just from sitting/age. None were really worth recapping so I sat them out for the electronics recycler to pickup.

 

[mindless1]

^ At a bare minimum I'd replace all caps on the 5V and 12V rail, and the 5VSB cap, then consider replacing 3.3V and then anything else electrolytic that's not one of the top brands like Nichicon, UCC, Rubycon, Panasonic, Hitachi. Replace Capxon, Teapo, Taicon, Samxon, OST, Elite, G-Luxon, Su'scon, Lelon, Fuhjyyu, Ltec, etc (any other you don't recognize).

I usually don't replace the big high side cap(s), they tend to last a very long time unless a brand you've never heard of. Well I wrote "caps(s)" but I no longer repair the ancient non-APFC design PSUs that use two caps for a voltage doubler and have the voltage selection switch on the back.

 

[IntelUser2000]

I'm just wondering if any of the PSUs may be an issue; could any of the capacitors (which I understand are the first things to go in a PSU) be on the way out (or already gone)? Or do PSU capacitors only age/burst at significant levels if they're being used?

They will ALL fail after some time, and not just capacitors inside. It's just a simple fact of life and you can even call it fundamentals of physics.

Have it inside a moisture-sealed bag, over time it'll fail and moisture will kick in since even from the beginning you cannot completely eliminate moisture and you cannot completely seal it. Hence they have a time which they recommend you should use it in your designs.

Also proper designs are important, even if you use all-Japanese high quality capacitors.

The thinking older electronics being reliable may be based on sound reasons. Larger components, leaded versus the brittle lead-free solder. Higher cost so it has higher quality components. Not speccing the design to the limit of the individual components.

 

[JEDIYoda]

They will ALL fail after some time, and not just capacitors inside. It's just a simple fact of life and you can even call it fundamentals of physics.

Tell my PC Power and Cooling 500watt PSU that I bought new back in 2005....... that is still running strong!!!

 

[mindless1]

^ Yeah it's a complex topic, having many different discrete components, all with their own lifespan vs running temperature considerations.

However, "typically", at any particular ( meaning normal operating) temperature, everything else will live more than double the lifespan of the electrolytic caps subject to high switching frequency (and fan), unless something else goes wrong like a fan failure gone unnoticed for a while, power surge, or bad design, defect, counterfeit parts, or it's 5PM on Friday.

You can only combat the inevitable wear items.. The rest, you roll the dice even if you elect to replace the PSU instead of continuing to use or repair it. Except there's also infant mortality for a new replacement... If I have a PSU running well for its purpose and can identify a fault, I have a fair amount of confidence that it will continue to suit its purpose if the fault is corrected, as long as it didn't damage the load when it failed.

In other words, "usually" I find that only fan or capacitors fail, before the powered equipment becomes obsolete, but I do take a fairly conservative attitude about what obsolete means, in no way do I consider something obsolete just because something shinier and faster comes long, rather does the widet (or computer in this case) serve its purpose, and if it doesn't serve my purpose, is it still of value to anyone else. Heh, here we tend to have high standards and hardware we retire, someone else would gladly have to use. Keeping hardware that "someone" would use, working, helps to reduce eWaste.

 

[jonnyGURU]

In other words, "usually" I find that only fan or capacitors fail, before the powered equipment becomes obsolete, but I do take a fairly conservative attitude about what obsolete means, in no way do I consider something obsolete just because something shinier and faster comes long, rather does the widet (or computer in this case) serve its purpose, and if it doesn't serve my purpose, is it still of value to anyone else.

Actually, outside of catastrophic failure, I've seen a number of examples of the TIM on SR MOSFETs drying up after a decade and causing OTP to trip when the PSU is relatively "cool" (cool being relative because an SR MOSFET easily hit 100°C).

One of the issues I have with using full package MOSFETs because you tend to only use a smear of paste as opposed to a thermal pad.

 

[mindless1]

^ of course that's possible, but seems like a smaller % of the herd, and when I refurb a PSU, I don't expect to use it at the original ratings, is demoted to some secondary use.

Many variables involved, for example I don't even bother buying/using a PSU if it doesn't have double the load rating of the system it'll be in, so all else equal, the fets have lower thermal density and pump out the TIM fluid less.

Then there's on/off system cycling, yet another variable...

In my niche applications, I've never had the TIM drying out, be a fault. I'm sure it is for some percentage of the herd in some situations...

It's highly subjective, where if someone doesn't know what to do, a new, HQ PSU is always the more conservative, safer option, but then there is education and conservation. Reuse what you can.

 

[JEDIYoda]

^ of course that's possible, but seems like a smaller % of the herd, and when I refurb a PSU, I don't expect to use it at the original ratings, is demoted to some secondary use.

Many variables involved, for example I don't even bother buying/using a PSU if it doesn't have double the load rating of the system it'll be in, so all else equal, the fets have lower thermal density and pump out the TIM fluid less.

Then there's on/off system cycling, yet another variable...

In my niche applications, I've never had the TIM drying out, be a fault. I'm sure it is for some percentage of the herd in some situations...

It's highly subjective, where if someone doesn't know what to do, a new, HQ PSU is always the more conservative, safer option, but then there is education and conservation. Reuse what you can.

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