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Old 10th December 2012, 11:19 PM   #1
Einric is offline Einric  United States
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Default Help with an ATX Power Supply Low 3.3v

I have a quite nice 850W "single rail" supply that just started giving low 3.3v.
It just started reading below 3v here in the past month.
As a result my computer has not been reliable.

So....I cracked it open to find two domed capacitors.
!WHAT LUCK!
What ya think my chances are that I replace the caps and everything starts working again?
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File Type: jpg Dome Cap 1.JPG (223.7 KB, 124 views)
File Type: jpg Dome Cap 2.JPG (162.7 KB, 118 views)
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Old 10th December 2012, 11:37 PM   #2
Einric is offline Einric  United States
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!EVEN MORE LUCK!

It looks like the fuzzy capacitor down in there in pic. 2 is attached to the 3.3v pin on the 24pin mainboard connector.
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Old 11th December 2012, 12:53 AM   #3
gmarsh is offline gmarsh  Canada
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Here's your problem - Capacitor plague - Wikipedia, the free encyclopedia

You should replace every electrolytic capacitor in the supply - or at least everything on the secondary side of the supply. They probably all came from the same manufacturer/series - and your +3.3V cap could have failed first, but your +5V/+12V/etc caps could be very close to failing also.

Based on the size of those main transformers and heatsinks, I seriously have my doubts that this an 850 watt supply - and a fake label generally indicates a lot of other bad things about the design. I wouldn't trust it, even with new output capacitors. I think you're best bet is to pick up a good, known brand power supply.
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Old 11th December 2012, 01:05 AM   #4
freax is offline freax  Australia
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What brand is it by the way?

It should be noted that I only trust Seasonic brands, know why? because Seasonic manufacture/design all of the pcb's and power supplies for every other brand of power supply out there.

If you pop open the lid of a Seasonic 430w and the lid of an Antek 430w you will notice they are the same pcb, the only difference is that the Seasonic has good brand capacitors in there and the Antek doesn't.

Antek actually lied to my face back in 2004 and told me that my power supply would last forever what with its 3 year warranty and good brand japanese capacitors, know what was in there? Fuujyuu brand.. and it was recommended to be a reliable brand, bla bla bla, sure enough 1 day before the warranty was to expire the computer started acting up (Watercooled AMD Athlon XP 2000+) and then the motherboard regulators blew up.

It should also be noted that I own 4 Seasonic psu's across 4 systems, 3 of them are 430w SII's and one is an x900, all of them except for one that I blew up by accident are still working 4 years after I bought them.

The X900 tho didn't have a ball bearing fan, it had a sleeve bearing fan which had to be replaced at about the 2.5 year mark (when it started making noise)

Unfortunatley every brand will try and cut corners somewhere and put in a little planned obsolescence, Seasonic have their fans and Antek and the like have their capacitors, I'd much rather have a fan die in one of them than a capacitor...or none at all, far less chance of damage to my computer then.
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Last edited by freax; 11th December 2012 at 01:18 AM.
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Old 11th December 2012, 03:51 AM   #5
Einric is offline Einric  United States
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It is a Silverstone DA850.
I am a little miffed about the False Advertising I have found in this supply.
It was marketed as a "Single Rail" supply but inside I found 12V 1,2,3&4.
It says it is an 850W with 70A of continuous 12V @50deg C.
Inside I found the main board marked for 750 with daughter boards marked 650.

I have had it for about 5-6 years now and has performed FLAWLESSLY at least 8 hours a day ever since.
That alone says alot with about 15k hours on the thing.
For the first 3 years I had at least a 50A load on the 12V "rail" most of the time.

These Teapo SC caps are only rated for 3000hrs, I am replacing them with Panasonic FR's that are rated at 10k hours @ 105C with ALOT more ripple.
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Old 11th December 2012, 03:58 AM   #6
Einric is offline Einric  United States
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It is OEM'd by Impervio
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Old 11th December 2012, 12:01 PM   #7
Einric is offline Einric  United States
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The first pic is a 2200uf 10V cap, it only measured 350uf.
The second pic I removed all three they are 470uf 16V, the domed one measured 220uf the other 2 still measured 511uf.
I ordered extras for the 470's I was thinking about doubling them up.
It would lower the ESR even more and double the ripple capability.
What do you think?

Last edited by Einric; 11th December 2012 at 12:08 PM.
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Old 11th December 2012, 12:48 PM   #8
MarianB is offline MarianB  Romania
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I would not hurry to double the caps, nor to modify the ESR, in fact i would try to get caps of the same ( or closest ) ESR possible and identicall capacity, cus both of them are used to calculate the compensation network and i doubt that there would be too much headroom for them, so in other words you could ( an d i stress could ) come up with an unstable PSU.
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Old 11th December 2012, 05:54 PM   #9
Einric is offline Einric  United States
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The FR's ESR is close to the Teapo SC, The FR is a little better ESR but way longer life and more ripple capability.
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Old 17th December 2012, 12:07 AM   #10
Einric is offline Einric  United States
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Well.....The parts showed up yesterday and I have just finished installing them.
I now have unloaded voltage readings of, 12.23, 5.11 & 3.42
I am feeling lucky so I will now shut down this computer and swap the Power Supply back into it.

EVERYBODY CROSS YOUR FINGERS.
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