HX620 power graphs

[Phantoms]

Was bored tonight and had my PICO 4423 scope home from work, so I thought I'd take it after my Corsair HX620W PS and see just how steady the volts are. Note that this is with all the peripherals hooked up and the PC running. The PICO is hooked to my work laptop.

So lets get started. Let's start with a 5 second capture of the 5v and 12v rails. 5v is blue, 12v is green.

Let's zoom in some....

A little more.....

Heck, this will take all day, let's zoom in on the 12volt line showing a positive and negative peak and see what it shows:

Hmmm, interesting. Markers in place and it shows from neg. peak to pos peak we have a variation of about 1v. It shows the approx. 44ms between the neg. peek and pos. peek.

Let's zoom in on the neg. peak:

This shows a neg. spike of nearly .5v with a total screen time here of approx. 76µs (thats 76/1000000 of a second, the PICO is one hell of a powerful scope).


Let's take a look at the 5v rail neg. peak to pos. peak:

This shows an time from neg. peak to pos. peak of approx. 80ms and a low peak to high peak difference af about .55v

Let's zoom in on the pos. peak:

This shows about a .3v pos. spike and this entire screen is approx. 77µs.

One more pic:

This shows the entire 5 second capture of both rails, with the max variation on the 12volt rail showing about 1.3 volts and the max variation on the 5v rail showing about .71 volts.

I did run an A/C ripple test which showed some nice ripple, but didn't save any of those screens. Please note that this capture was taken with the PS in the PC and operating, drives running, etc. The overall pattern looked pretty decent. Not extraordinary, but not as bad as some crap PS either. I just thought some here would enjoy a good capture of the older Corsair 620W (been in service about 2 yrs.) .

 

[Phantoms]

And if you want to know just how powerful the PICO 4423 is, take a look over this thread. You will not find a much more powerful DSO.

 

[[Spectre]]

What probes did you use? Where did you probe the wires? What capacitors did you have in place?

 

[Phantoms]

Paul, I hooked up probes to the 12v + and - and 5v + and - of an empty drive lead. I hooked up to channels A and C of the scope to be able to use the full resolution of the Dual 80MHz ADCs (one runs channels A-B, one runs channels C-D). No capacitors were used and doing so would only skew the results.

This is one very powerful scope and would show much the same (I believe even for the HX800W you just tested) for most high quality Power Supplies. This was a single capture of 5 seconds with a resolution down to a microsecond (µs) without any info being lost. At this high a resolution you can capture these micro spikes that happen in approx. 1µs. You also have to consider this PS is hooked to a system that is operating, not a constant load device. This means HD activity, GPU activity, CPU activity and all that can cause quick variations and spikes in the power being supplied.

If you want to see just how powerful this scope is, go to Pico for the latest release of their software (http://labs.picotech.com/ for the latest beta) which is full featured. You can run it in Demo Mode for all the available PICO DSOs (I'm running the PICO AUTOMOTIVE Scope with a 4423 unit) and see it's capabilities. It has a streaming mode and block mode (block mode only without an actual scope hooked up). I use this scope for work and there is not a more powerful Automotive DSO around. PICO does make more powerful non-automotive scopes but with the specs the 4423 has, you'd be hard pressed to find a place where you'd need one in it's place.

 

[[Spectre]]

No capacitors were used and doing so would only skew the results.

No the results would have be specification compliant had you used the proper probes and capacitors.

As it stands those large drops and spikes are most likely due to probe noise and/or are artifacts.

 

[Phantoms]

Paul, maybe with what you are using, buffering the signal with a capacitor is required for the type of results you are trying to capture.

I was not measuring to any specifications or trying to allude that I was. I was taking a extremely high resolution capture to show micro spikes that are present in all Power Supplies. I'm sorry if you misunderstood.

The probes are low noise and shielded extensively end-to-end. It is not random noise you are seeing in the signals. I test in an automotive environment where noise is everywhere requiring only the best of scopes and leads to keep it out. The only noise picked up in that capture is off the wires themselves and that is not that uncommon at this high a resolution to be able to see it.

 

[Phantoms]

Paul, I captured some noise for you at work so you can compare. This is in a shop environment with cars running, shop fans, etc.

These are captured at the same settings with the leads attached and open to the air.

Here's the 5 second capture:

and here's the zoomed capture showing in a few µs:

As you can see the noise peaks at about 40mv, no where near the half-volt spikes that were showing on the PS captures. These few mv of noise would shrink to well less than 10mv hooked up to a circuit.

 

[[Spectre]]

That is fine, having worked with SMPS for a while I can tell you .5V changes are most likely artifacts and not inherent in the design.

 

[timme]

Umm... is that good?

 

[Phantoms]

Paul, they are an artifact in the sense that it is actually introduced in the power wires by system components operating.

Timme, you have to consider these .5v spikes are occurring for less than 1/1000000000 of a second (the PICO can actually measure down to 80 Million samples per second), and most likely a spike caused by some change in the system (a drivehead moving, etc.) since these captures are from a running system. This means the PS is catching and regulating the voltage change in that time period. To catch system instability, you'd measure under a much slower timebase with as constant a load source as you can find. As I said at the beginning, I was bored and had the scope at the house so decided to do some high speed captures. Used at my work I usually capture at the same settings for most things, but do not need to zoom in to as high a resolution to find the common problems (a crank sensor signal dropping out, etc.), the same as Paul doesn't need to test at such a high resolution to tell the stability of a PS.