Burned out PSU x2

[rbsteffes]

My little sister at college has managed to kill two PSU's in under a year. She's in an old dorm with unknown wiring, but she swears she had them both plugged into a surge protector. Both PSU's were generic brands (I didn't see either of them) put in by a computer shop.

Last time she had to replace the motherboard too, this time she woke up to a "burning smell". I'm loathe to let her replace this PSU and go back and burn it out again. It's possible it's bad luck, but I'm still wary of the wiring at her school. What can I do, besides encourage them to buy a decent brand this time?

Would a cheap UPS "condition" the current enough to prevent a repeat? If it's the wiring, why wouldn't the surge protector, well, protect it?

Computers I'm good with, software I know. Electricity, well electricity and I don't get along very well. Anyone got any suggestions?

[kesv]

Would a cheap UPS "condition" the current enough to prevent a repeat? If it's the wiring, why wouldn't the surge protector, well, protect it?

Surge protectors need good wiring to work like they are supposed to. Particularly the grounding should be properly implemented, because that's where the surge protector is supposed to direct excess power (it can't really absorb it itself).

A real UPS where the power always flows through a battery should be a little better in this respect, however nothing can totally compensate for bad wiring.

[Talz]

I would get a brand name UPS, you can find some decent deals ($100 or less) if you look around. I would look for one that lists power conditioning as one of it's features or benefits like the APC ES series, though any decent UPS should do more than a standard surge protector in this regard. But you are on the right path imo, a surge protector doesn't do anything about bad quality power, only very large spikes and surges.

So yes a good UPS, Tripplite, APC or similiar. And get a good power supply, no good reason to cheap out there when you can find a good 300 watt for $50 or so.

[sthayashi]

If the AC voltage is sagging for some reason, it could easily burn out the PSU. MikeC has shown that a PSU can draw as much as 500W at 80VAC, when it would normally do 300W at 120. A good UPS should help here.

Another possibility is that her PSUs are burning up temperture-wise, before they give up the ghost electrically. Be sure she gets a brand-name replacement.

[MikeC]

PSUs are most stressed by brownouts and other often-short term drops in AC voltage. And grunge (distortions in the 60Hz wave). Chances are, the VAC in your sister's dorm is low/fluctuating.

Get her an AC power meter if you want to be sure -- Seasonic's new Power Angel or the KillaWatt would work.

The best way, technically, to deal with this is to use a true UPS -- one that uses the AC to charge a large battery, and for the PC to be driven off the battery's out (which has to be converted back to AC -- bit of a waste). But that's an expensive solution.

It might be cheapest / easiest for her to get a notebook, get 2 batteries, and always run the notebook off the batteries.

PS -- replacing the PSU with a quality model that handles low VAC well might be worth it. Where to get this info? Well it will be coming here in PSU reviews soon.

I've been playing around with an AC variac that lets me feed a PSU/PC with any AC voltage from 0~140VAC, even while the PSU is trying to draw enough power for full power output. Only a few have been tested, but I have found the Seasonic Super series have an amazing ability to keep pumping out power consistently even when the VAC drops below 90VAC. I have burned some other PSUs with this test.

[rbsteffes]

I'm guessing that's the problem. I need to keep the combined total as close to $100 bucks as I can.

I'm browsing the UPS listed on newegg as a point of reference. The numbers I need to look for are models that have a greater tolerance for input variance?

Say something like a:

BELKIN Office Series 550VA UPS, Model "F6C550-AVR" -Retail
VA Rating: 550VA
Battery Run-time: 28 Minutes
Battery Recharge Time: 8 - 12 Hours
Input Voltage & Frequency: 90–136 +/- 3V AC
Output Voltage & Frequency: 120V AC +/- 5%, 60 Hz
Protection: Thermal Breaker Device


would be better than

APC 350VA Back-UPS ES 350, Model "BE350U" -RETAIL


- Specifications -

VA Rating: 350VA
Battery Run-time: 8.1 minutes (100 Watts), 1.6 minutes (200 Watts)
Battery Recharge Time: Not Specified
Input Voltage & Frequency: 120V, 60 Hz +/- 1Hz
Output Voltage & Frequency: 120V
Protection: RJ-11 Modem/ Fax/ DSL protection (two wire single line)
Dimensions: 6.9" x 10.9" x 3.3" (LxWxH)


Or am I missing it?

[MikeC]

The UPS specs you cite refer to the VAC tolerance/range for itself -- not for the PC or equipment connected to it. All cheaper UPS models simply pass the AC straight through unless the VAC drops down far enogh -- the VAC point at which the UPS battery kicks in probably varies a lot, and there's no easy way of telling what this VAC point is for each model. For a poor VAC-tolerance PSU, you'd want the UPS kicking in at the slightest drop in VAC. For a top quality PSU that's tolerant of greater drops in VAC, it would be less critical.

I think the quality of the PSU is probably more important than the UPS/line filter, because most of those don't do much till you pay a LOT of $$.

[rbsteffes]

Thanks for the help. The feature I'm looking for, for the benefit of others stumbling through this thread, is "AVR".

The model I'm looking at now is the "Belkin Office Series 550VA UPS Part # F6C550-AVR" unless anyone has any strong feelings or good advice in another direction.

[Talz]

Really don't have much to say about Belkin, it should be decent at least. The only widely distributed brand I would specifically avoid is Newpoint. I had one of those melt a hole in its housing and feel pretty lucky that it did not catch the house on fire while I wasn't around.

[MikeC]

OK, I'm not trying to confuse you here -- or promote Seasonic: So the mfg says Automatic Voltage Regulation, but what does that really mean? There are no detailed specs to expalin that. And how effective is it? How about in comparison with another brand? Without at least a bit of this info, are you not just buying on the basis of a PR claim -- much like "Ultra Silent" to repeat a claim made by some PC component brands.

I still think if you budget is <$100, you're better off getting a higher power Seasonic Super model & keeping your fingers crossed. I don't think that a cheap AVR UPS is much better, because we don;t even know the real causes of the the PSU breakdown in your sis' PC. You might also suggest to her to turn the PC off and even unplug it (or turn off the swtich on the powerbar / surge protector) when not being used.

Again, I'm not trying to promote Seasonic, it's just one of a handful of PSUs I tested at reduced VAC, and it was consistently the best performer by a good margin. (Others in the mix: Fortron [same as Zalman & Nexus], Antec, Chill Innov)

[rbsteffes]

Appreciate the concern Mike. Ultimately though, the solution I went with played as much into psychology as physics.

I bought the Antec Ralf had listed in the Dealer/Surplus post, which may be able to handle the problem itself. The USB is as much for peace of mind as it is likely to help anything. My Mom is now convinced after being told that she needs a UPS for my sister by the computer store that she now needs one. It'd be far easier to convince her to buy two devices that she's been told she needs, than one for twice as much as she thinks it should cost.

Here's to hoping the combination works, even if it isn't clear which did the job. Besides, I figure it's only got to give her time to save one paper if her power goes out before it's worth the $50.