Why 99% of Power Supply Reviews Are Wrong

[ChampionLLY]

Introduction

With computers (and users) asking for better power supplies, nothing more natural than reviewing websites publishing power supply reviews. But contrary to other hardware parts like CPUs, motherboards and video cards, one must have deep electronics knowledge in order to test a power supply. Since most reviewers are simply users with a above-the-average knowledge in computers – but not in electronics – almost all PSU reviews posted on the web are completely wrong and they do more harm than good, as some websites recommend products that are really flawed. In this article we will explain in details why 99% of power supply reviews posted on the web are wrong and we hope that reviewers learn more about the subject by reading this article and also that users learn how to identify a bad review.

The methodology most used to review power supplies is just adding a multimeter on the power supply outputs and measuring if there are any fluctuations on the voltages found there. Some websites even compare the voltages found with voltage levels found on competing products. The problem is, this procedure is wrong and tells us nothing about the power supply.

The most common problem with power supplies is their incapability of delivering their labeled current (and thus power). Measuring the output voltages will tell us nothing about this....

Read the whole article @ http://www.hardwaresecrets.com/article/410

stunning article!
quite technical i would say, but its a MUST read

[empire23]

Agreed, a real power supply test should rely on how much load the power supply can handle and the amount of harmonics it outputs at the same time.

BUT

- You'll need a programmable load, like one from Chroma or Agilent to present a load to a PSU either via dynamic or static load.
- You'll need an Oscilloscope, to detect harmonics and defects within the voltage output and transients.
- Crossload characteristics require you use a powershunt in conjuction with the above.
- IR themometer to see whether any of the bridge diodes, PWM transistors are going out of operational temp spec.
- Clamp for AC power draw and relative power factor testing comparing real and apparent power draw.
- Proper SPL metering for sound, not some A-weighting crap but a proper measurement standard like the ITU-468.

It's not a lack of knowledge per se, it's just that..................THAT SHIT IS FREAKING EXPENSIVE!!!! LOL, really, a Chroma can cost up to 4k-5k ringgit, an Oscilloscope (i'm looking at the 5400 ringgit Tektronix TDS2002B) for around 4k, IR thermometer for around 500 (around 780 for ones that can log variance), Clamp meter attachment (440i) for my Fluke for around 780, SPL meter for about 500 more (A-weighted, for ITU-468, expect to pay around 800).

But not is all lost, at least my F179 multimeter is professionally calibrated to ISO and IEEE specification (200 bucks for calibration, cry me a bloody river)

Nah, reviewers like me are competent, the only problem is that we're poor.

[Chai]

Read it before.

Well, proper testing always cost a lot of money.

[empire23]

We could rob those agilent dudes in penang, imagine the programmable DC loads, 6 ghz Infinium scopes, Spectrum Analyzers, Probes and cute female workers we could steal.

But if i do ever decide to make power supply testing my full time thing, for the price, i'd suggest the Chroma 6314 (5k ringgit give or take). Agilents are just too expensive and unneeded for SMPS testing (10k give or take). But there are stupider and cheaper ways, like buying 4 200USD 2nd hand Yokogawa dynamic loads and loading them across the voltage lines. And heck lemme give you a drawing of my dream setup, not totally high end, but relatively accurate.

[ChampionLLY]

very chim...

[Max_87]

way too chim

[empire23]

But this does give me the idea, if we actually did get this test equipment and provided very accurate tests and got more visitors, how long would it take us to repay it all? Hmmmmm veli intelesting one..!

Ask Dato Adrian sponsor me one Infiniband scope lah. My scope is coming, model TDS2002B (comes with data aquisition leh hehehhehe), IF my nefarious tax evasion schemes work out (In ur face Kastam Malaysia!), SPL meter next month, thermometers (IR and Bead) are ready.

So technically, all i need is a loader and a Variable AC supply. Budget ARP 2007 got provisions for this kah? After this, i'll have ze ultimate PSU test rig short of RF harmonic injectors and Spectrum analysis!

Aiseh, when it comes to testing and electronics, i just lose it and start jabbering away.

[Papercut]

Dare to dream...maybe you can be the next JonnyGuru

[ZuePhok]

nah..top sites can easily afford that.
it's just a question of whether they are willing to invest on expensive equipment or not..

[empire23]

Originally Posted by ZuePhok

nah..top sites can easily afford that.
it's just a question of whether they are willing to invest on expensive equipment or not..

More reason to rob the Russians and Anand lol.

Well, i do consider an investment in such equipment a long term one. I've seen people use Fluke 88Vs for 20 years without a hitch and HP Agilent scopes for more than that without much recalibration required. Anyways being in the business of EE and computers, as far as i'm concerned, these tools are the bread and butter of every engineer and that's why i try my best to save up for them.

There are even more insane ways to measure performance, but at the end of the day the only stat that matters is the stat on the box, since we aren't the circuit designers and thus can't put a performance level on it, is does it live up to the specifications on the box and how well does it do it?

So far Tektronix hasn't replied my mails requesting a quote, Christmas holiday i guess.