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**Th3_uN1Qu3** · 03-02-2011, 01:59 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

Are you sure you are using the x10 probe? Edit: Scratch that, the maximum sensitivity is only 10mV/div, with a x10 probe that would be 100mV/div... not barely enough to see ripple on a decent PSU. You're going to need to make your own compensated x1 probe. I had a few links, will look thru them and post them later.

**c_hegge** · 03-02-2011, 03:31 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

Thanks!

**c_hegge** · 03-02-2011, 06:27 PM

Re: Hantek DSO-2090 USB Oscilloscope problem

In case it helps, I've attached some images of the outputs. The first one is with the main probe connected to the +5v of a PSU with the small grounding wire clipped to the case. The second is with the main probe at the +5v with the ground not connected. The third is with the probe attached, but not connected to anything, and the fourth is with no probes attached at all. The first two look exactly the same no matter what PSU I connect it to and what output on the PSU I connect it to.

Attached Files

**Th3_uN1Qu3** · 03-02-2011, 11:47 PM

Re: Hantek DSO-2090 USB Oscilloscope problem

The grounding wire clipped to what case? I hope that was the case of the PSU. Anyway, try hooking it to a black wire of the PSU directly.

But first let's see if it's not broken. Using Sound Forge or Audacity generate a 1kHz tone. Unplug your speakers and plug into your soundcard a cable which you can attach your scope to. Hit play. See what you get.

**c_hegge** · 03-03-2011, 12:41 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

The ground wire was connected to the PSU's case for the images I posted before, but it was the same with it connected to a black ground wire. I found a spare audio jack cable and connected that to my sound card and generated a 1KHz tone with Audacity. I connected the black grounding wire from the probe to the ground wire in the cable and the main probe to one of the wires. I tried it at differrent Time/DIV settings. The first picture is at 40uS, the second at 200uS and the third at 400uS.

Attached Files

**Th3_uN1Qu3** · 03-03-2011, 12:53 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

Was the volume maxed? A soundcard puts out a fair bit more than 70ish Vpp, more like 1.something volts. If you are using a x10 probe this result is to be expected. Try the x1 probe.

**c_hegge** · 03-03-2011, 01:14 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

OK. Here it is with the 1x Probe. The First Picture is with no sound, Second with 1KHz at 40uS Time/Div, 3rd is at 200uS, 4th is 400uS

Attached Files

**c_hegge** · 03-03-2011, 02:14 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

It looks like the whole problem might have been the 10x probe. I connected it to an Antec which I knew had bad caps on the 5vsb with the 1x. Here's how it looked when connected to a cheap PSU tester. First Pic is the +5 output, second is the +12 and the third is the 5sb rail with 3.4V of ripple. Any ideas as to why the big spikes on the +5v and +12v rails? Maybe it needs the two caps in parallel with it?

Attached Files

**Th3_uN1Qu3** · 03-03-2011, 05:02 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

Yes, intel testing procedure is 2 caps in parallel one lytic one ceramic but i don't know from memory. Google it.

**c_hegge** · 03-03-2011, 02:47 PM

Re: Hantek DSO-2090 USB Oscilloscope problem

Pretty sure it's a 10uF electrolytic and a 100nF/0.1uF ceramic.

**severach** · 03-03-2011, 09:20 PM

Re: Hantek DSO-2090 USB Oscilloscope problem

Originally posted by c_hegge View Post

with the small grounding wire clipped to the case.

Don't do that. In a switching power supply the placement of the ground is as important as the placement as the probe. Place the ground and probe across the cap being tested and know that the waveform only applies at that point. As you move along the trace or plane the wave will change.

**Th3_uN1Qu3** · 03-03-2011, 10:48 PM

Re: Hantek DSO-2090 USB Oscilloscope problem

Originally posted by severach View Post

Don't do that. In a switching power supply the placement of the ground is as important as the placement as the probe. Place the ground and probe across the cap being tested

The computer doesn't feed directly off the caps you know. Maybe you meant the probe and ground on the rail being tested.

**severach** · 03-04-2011, 10:36 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

Originally posted by Th3_uN1Qu3 View Post

The computer doesn't feed directly off the caps you know. Maybe you meant the probe and ground on the rail being tested.

Testing at any random point along the rail isn't very useful. You need to test at the points where you can improve something or where the power is being used.

**c_hegge** · 03-12-2011, 03:52 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

OK. I got the two small caps and it seems to work great. I've made a few adjustments to the load tester too. I soldered a few extra wires to the ATX Connector (1 for each rail + 1 ground) which go into a 6-way switch, allowing me to select which rail to monitor. I tested a Bestec ATX-300-12Z. Here's how it looks when overloaded to 405W. The ripple was in spec, but the primary switcher exploded after about 5 minutes. Pictures, from left to right are 12, 5, 3.3, -12, 5sb. Thanks Th3_un1qu3

Attached Files

**Th3_uN1Qu3** · 03-12-2011, 07:55 AM

Re: Hantek DSO-2090 USB Oscilloscope problem

Good job.

@ severach i'll say it again - you should always test at the end the load is hooked at. Otherwise the numbers are meaningless.

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Hantek DSO-2090 USB Oscilloscope problem

Hantek DSO-2090 USB Oscilloscope problem

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