Pure Sine Wave UPSes for New Dell PCs

Hi!

1- Dell technical support reps don't know what a PFC power
supply is, and aren't sure whether any Dell computer has one.

I am not sure why that comes as a surprise. To them, a power supply is
a silver box with wires. They might know it has a fan or two inside.
They also know that when power supplies in computers fail, you send
out a new replacement.

Few people do component level repair on power supplies. I've been
incredibly frustrated in my attempts. The only reason I tried is
because the supplies in question aren't made any more, and I've been
losing them at a rate faster than I can replenish my supply. (In case
you're wondering, the supplies are the 335 watt Delta SMP-332AB units
from IBM PS/2 Model 95 computers. All I know about the failure is that
the controller is being told to shut down, and that was what someone
much better equipped than myself and more experienced had to say about
it.)

And it's dangerous--switching power supplies can supply enormous
amounts of electrical current, the high switching frequency can really
bite if you happen to come in contact with something operating at that
frequency and portions of the circuitry are directly line connected.
That last one makes for an extremely dangerous environment, as the AC
power in your home can deliver more than enough current to seriously
injure or kill you.

3- None of the big UPS makers will come out and say: You
can't use our home and small office UPSes if your computer
has a PFC power supply.

That's because it certainly *should* work. If I ever come into one of
these Dell machines where the power supply doesn't "like" a stepped
sinewave input, you can bet that I'll be doing a teardown.

I'm deadly serious:
http://greyghost.mooo.com/hdtunetakeapart/
http://greyghost.mooo.com/rx4109takeapart/
although I usually don't go to the trouble of making web pages, or
even ones really intended for public consumption.

Anyone want to send me one of the PSUs for an exam? Private e-mail can
be found from the above pages or wct atsign walshcomptech dot com.
I'll return it to you fully reassembled, and it's unlikely to be
damaged in the process because I take extreme care when doing these
things. I will test it prior to returning it, and should it not work,
I'll front the cost for a replacement.

(Yes, that's only my word, but it's all you need as I take it quite
seriously.)

4- None of the formulas, online calculators or techniques to
calculate or estimate the correct size UPS for your computer
arrive at the same conclusion.

Couple of explantions: 1) there's more than one way to skin a cat, 2)
everyone has a different idea, 3) some are more truthful than others.
I'd put more faith in a calculator constructed by someone who *uses*
UPS units than I would someone who is *selling* them.

5- Nobody agrees on the correct method to calculate or estimate
the correct size UPS.

See above.

6- No OEM will tell you: If you are thinking about purchasing this
particular computer, consider this: It will require a UPS that will
cost you half as much as the computer itself for adequate power
protection.

It'd cost them the sale, and maybe in the worst case, even land them
in a court of law to defend their actions. When a computer from the
competition can be proven to operate perfectly on stepped sinewave
output, why won't theirs?

Not saying that's correct, but you can be sure it's how the average
consumer is going to view it.

7- No UPS maker will say whether they'll honor their warranty
if you use a stepped approximation unit with a PFC power
supply.

If the warranty to which you refer is the one that covers the UPS
itself against any failures or issues, they don't really have a choice
outside of snubbing the customer or coming up with an allegation that
you were abusing the unit. There are some pretty strict laws governing
what can and cannot be excluded or limited in a warranty, at least in
the US. It's unlikely that the UPS would be damaged even if the
computer failed to operate correctly from the power supplied by said
UPS.

As for any such "connected equipment warranty", these are practically
worthless. You should not buy power protection equipment based on what
any such policy might claim. I suppose that someone, somewhere has
received a payout from one of these policies, but when you think about
it, only a fool provides a multi-thousand dollar warranty for the few
tens or hundreds of dollars that represent the profits from the sale.
If you haven't, look at the fine print in one of those things
sometime.

I apologize for ranting.

No problem. Sometimes you just gotta speak your mind. :-)

William

Daddy,

Great summary. I'll wait for your recommendations.

My XPS 420 has a 425 watt ps
Using an APC Back-Ups RS 1500
Under Power Chute Software it shows
121 watts of the available 865 watts @ normal usage

I live in an area with a flakey power grid
Power loss during a storm is pretty common

The computer works no different on battery.
No noises or any odd behavior

John
On Fri, 09 Apr 2010 20:04:31 -0400, Greg S
wrote:

On Fri, 09 Apr 2010 00:31:04 -0400, Daddy
wrote:

Tom Lake wrote:
I maintain that Dell is cheapskating on the quality of their power
supplies, and they may have a nasty backlash from doing so. (But then
again, I'm a pretty big believer in "do it right the first time" for
stuff like this.)

Not necessarily. The PS in the 9000 is rated for 475 Watts and puts out
a true 475 Watts. I've seen some name brand supplies put out less than
their rating.

Tom L

Well, I conducted my little experiment...pressed the power button on my
UPS to turn it off, and...my computer and monitor immediately shut off.

That's not necessarily because my UPS doesn't produce a sine waveform.
For one thing, at 550 VA, my UPS is way under-powered. For another, this
sissy little UPS probably doesn't have a fast enough transfer time.

By the way, don't waste your time asking Dell technical support about
power supplies or UPSes. They don't have a clue.

Daddy

The specs for my 6-month old Precision 3400 included the sine wave UPS
recommendation. While the 375W PS is smaller than many (yet more than
sufficient for my needs), my BACK-UPS ES 750 has always worked
flawlessly with this machine. Just one user's experience -- YMMV, of
course!

"William R. Walsh" wrote:
..... The fuser demands an
enormous inrush current whenever it fires, and this will overwhelm the
inverter in all but the very largest UPS units, causing it to shut
down (best case) or fail in an exciting way.

William


What's a "fuser"?

*TimDaniels*

A question about UPS. Say it's rated as 500 watts (watts not VA).

That means on battery it can run a 500 watt device for a period of time.

But, does it mean you can't plug a 1000 watt device into the non battery
side of the UPS? Or is that side of the UPS just like a power strip where
you can plug in a 2000 watt heater?

On Sat, 10 Apr 2010 09:08:18 -0700, "Timothy Daniels"
wrote:


"William R. Walsh" wrote:
..... The fuser demands an
enormous inrush current whenever it fires, and this will overwhelm the
inverter in all but the very largest UPS units, causing it to shut
down (best case) or fail in an exciting way.

William


What's a "fuser"?

The heating element that melts ("fuses") the toner onto the paper.

Hi!

That means on battery it can run a 500 watt device for a period of time.

A very *short* period of time, yes. It's not a good idea to run a UPS up
against its limits, because they are usually worst-case values that the unit
won't stand for too long.

But, does it mean you can't plug a 1000 watt device into the non battery
side of the UPS? Or is that side of the UPS just like a power strip where
you can plug in a 2000 watt heater?

The outlets on the UPS that do not have battery backup may be used as
conventional outlets, with any load that is suitable for them. In the US, an
outlet could safely supply 15 amps at 120 volts AC. As long as you do not go
over 15 amps total (add up the amperage ratings for each item, whether it's
plugged into the battery backed outlets or otherwise), you can put whatever
you want on the outlets that are not battery backed.

William

Hi!

I think you are deescribing the"Kill-A-Watt".

That's one (and it's the one I happen to have). There are some others that
are stocked by major electronics and parts dealers, sometimes under a
private label.

I know of a case where a UPS wouldn't supply juice if it wasn't
plugged into the utility mains. It was a "field day" exercise and the
intent was to power a WiFi repeater off the grid.

That might be a safety concern (floating ground) or perhaps the unit was not
cold start capable. Not all UPS units can start up their inverters without
first being on AC power, but most can. Older APC units in particular won't
do this--they must start from AC power first.

William

"who where" wrote:
"Timothy Daniels" wrote:

"William R. Walsh" wrote:
..... The fuser demands an
enormous inrush current whenever it fires, and this will overwhelm the
inverter in all but the very largest UPS units, causing it to shut
down (best case) or fail in an exciting way.

William


What's a "fuser"?

The heating element that melts ("fuses") the toner onto the paper.

OK, thanks. I do notice that my desk lamp dims for about
a half a second whenever my laser printer starts up. I guess
that's due to the fuser warming up.

*TimDaniels*

Thanks for that.

I have my UPS set for 1 minute on battery before it shuts the computer down.