Measuring Power Supply turn on glitch with Siglent 1202X-E

[mikepa]

Just received my Siglent 1202X-E and first task was to measure the power-on glitch of my HP E3615A power supply. So far I've failed to make the measurement!

Lab supply is set to 5v, trigger at approx 1V.  I have the scope setup for single shot. When I turn on the supply, the scope triggers, but shows zero volts (See pic).

But if I leave the supply on, and I connect the scope to it, I see a 5v step (See 2nd pic)

Whats going on?

(BTW, I got the scope for $311 from Amazon Warehouse Deals.  Was supposedly "Used - Very Good condition with minor marks".  Looks flawless to me, was still in original plastic and "startup times"on system menu is 1.)

[nctnico]

Well you found your first mains induced spike! Look closely at the screen (turn up the brightness, enable peak detect to see it better).

[pascal_sweden]

How much did you save from the listed retail price?

How is the warranty policy for Amazon Warehouse Deals?
Do you get the full 2 years or are you completely on your own?

Where do you need to send the unit to for service or repair?

[StillTrying]

"Lab supply is set to 5v, trigger at approx 1V.  I have the scope setup for single shot. When I turn on the supply, the scope triggers, but shows zero volts (See pic)."

Probably EMI from the switch on. Try moving the trigger level higher 4V? Turn 20MHz BW limit on? Try trigger HF reject. Use a slower X speed.

Edity:
Now I've had a very close up view, I can see the spike in the first pic. it's 1.25 divisions high.

[klaff]

Set the trigger to Normal, then turn on your supply. Then press the History button and you'll be able to switch between the last frame (with the trigger you wanted where the supply really came up) and the previous frame (with the trigger caused by the arcing of the power supply power switch).

[tautech]

On the captured waveform (Stop'ed) increase the timebase to view what happened at the Trigger point.

[mikepa]

Thanks guys. I tried klaff's history suggestion, but there is only one frame, the power switch arc.  The supply coming up to 5v isn't captured; I tried different trigger levels, no joy.   (This is my first DSO, had analog scopes in the past.)

pascal_sweden brings up a great point as far as Amazon Warehouse deals warranty goes .... I incorrectly assumed it came with full warranty, but it doesn't!  Standard Siglent warranty is three years, so I guess the $311 Warehouse price (vs $379 from Amazon) maybe not quite as good as I thought. 

Very happy with scope so far.  Only minor quibble is the buttons are a little too soft.

[StillTrying]

The scope will easily capture what you want. Move the trig position from the center quite a few divisions to the left, and turn the X speed down to 20ms/div or 50ms/div.

[mikepa]

Thanks StillTryin, the slower timebase did the trick. PS rise time is 4mS.

FWIW, the HP does a good job with no overshoot.

[TK]

The spike can be larger... try chaging the timebase to see the spike in more detail.  I don't think @ 1ms you can see it. Or try another capture setting the trigger over 5V and see if the scope triggers.

As nctnico says: There are small lies, big lies and then there is what is on the screen of your oscilloscope.

[StillTrying]

Try setting a low current limit (50mA - 100mA) on the power supply, and see if its 5V rise time is slower.

[klaff]

Thanks guys. I tried klaff's history suggestion, but there is only one frame, the power switch arc.  The supply coming up to 5v isn't captured; I tried different trigger levels, no joy.   (This is my first DSO, had analog scopes in the past.)

Hmm.  I tried to duplicate this and the History behavior isn't always the same. Sometimes I'll get 2 frames (or a lot more depending on samples, sweep speed, etc.) but sometimes it only has 1.  I'm not yet sure about the rules here. I've had the scope for a couple of weeks. There are a few bugs but there's supposed to be a firmware update coming and it's very useful as is.

[tautech]

Thanks guys. I tried klaff's history suggestion, but there is only one frame, the power switch arc.  The supply coming up to 5v isn't captured; I tried different trigger levels, no joy.   (This is my first DSO, had analog scopes in the past.)

User error or just no knowledge of the power of a DSO.

Thanks StillTryin, the slower timebase did the trick. PS rise time is 4mS.

Your pic looks like it was captured with Normal triggering.
Earlier ones are OK too, you just have to adjust the timebase to see the fine detail after the scope has captured the event.
There are a few ways to get the results you seek, you just need to learn them. 
Have fun.

[mikepa]

Thanks again for the assistance guys, I learned a few DSO lessons here, not to mention a caution about Amazon Warehouse sales.

[pascal_sweden]

pascal_sweden brings up a great point as far as Amazon Warehouse deals warranty goes .... I incorrectly assumed it came with full warranty, but it doesn't!  Standard Siglent warranty is three years, so I guess the $311 Warehouse price (vs $379 from Amazon) maybe not quite as good as I thought. 

The standard Siglent warranty is 3 years. How much warranty did you get?

When you buy the scope from an official distributor, you can send the scope to them for service or repair.
Where do you need to send the scope for service or repair?

[mikepa]

Hi Pascal_sweden.  According to https://www.amazon.com/gp/node/index.html?ie=UTF8&marketplaceID=ATVPDKIKX0DER&me=A2L77EE7U53NWQ&merchant=A2L77EE7U53NWQ&redirect=true

  Do products come with a warranty?
  No. Used products generally do not come with a manufacturer's warranty but all of our items are backed by Amazon’s return policy. If
  you would like additional protection, you can purchase a warranty from Square Trade to cover certain items.

I don't see a list of dealers on Siglent's web site, so I'm not sure how one finds out if Amazon is authorized or the other store (Sealig) that is mentioned in the Amazon listing.  (Is Sealig a siglent company store?).  It sure looks like I don't have any warranty at this point, so have to give consideration to returning the item and repurchasing with a warranty.

[pascal_sweden]

If you can still return the unit, I would return it and ask my money back.

It's better to buy a brand new Siglent scope from an official distributor.

This way you have full support and full warranty.

How much dollars did you save? Not many if I read correctly.
So again, I would return the unit and ask my money back.

It does not make sense to drop a 3 year warranty period and free support, for the peanuts that you saved.

[Kleinstein]

There likely is nothing wrong wit the scope or the supply. It is just a matter of the initial spike from the mains turn on that triggered the scope. To resolve this the different settings seem to have worked. Also the cabling to the scope can make a difference.

[colorado.rob]

(Is Sealig a siglent company store?).  It sure looks like I don't have any warranty at this point, so have to give consideration to returning the item and repurchasing with a warranty.

Not only are Saelig an authorized seller, they are active on EEVBlog and provide EEVBlog members a discount if you ask for one here: https://www.eevblog.com/forum/testgear/equipment-discounts-from-saelig/

[StillTrying]

I had a google for the warranties of amazon's warehouse deals myself and thought it looked like a nightmare. I think it would be a very good idea to find any faults well within the first 90 days.

www.amazon.co.uk/Amazon-Warehouse-Deals/b?node=3581866031

[TK]

If the manufacturer does not stand behind its products, it is not worth the $$$ you apparently are saving... Keysight, Rohde&Schwarz and other scope manufacturers honor the warranty per instrument, they don't ask where you purchased it, if you purchased it used, etc.  Chinese scope manufacturers seems to avoid offering transferable warranty on their products.

[rf-loop]

Thanks guys. I tried klaff's history suggestion, but there is only one frame, the power switch arc.  The supply coming up to 5v isn't captured; I tried different trigger levels, no joy.   (This is my first DSO, had analog scopes in the past.)

Hmm.  I tried to duplicate this and the History behavior isn't always the same. Sometimes I'll get 2 frames (or a lot more depending on samples, sweep speed, etc.) but sometimes it only has 1.  I'm not yet sure about the rules here. I've had the scope for a couple of weeks. There are a few bugs but there's supposed to be a firmware update coming and it's very useful as is.

This preliminary table show max segments in sequence mode. Also it show maximum history waveforms with different timebases (memory lengtht).  If you want more waveforms in buffer with slow time bases you need reduce one waveform memory length ( of course it also reduce samplerate, it is pure math with one waveform length and timebase. Example if timebase is 1ms/div there is 14ms long wavefrom. When memory is 14M it can use 1GSa/s because there is 14000000 memory places for samples. 14000000 x 1ns = 14ms )

[mikepa]

Amazon Warehouse Sales has its own website listing all their deals - some like the Tektronix 1052B scope specifically list a five year warranty is included for the $442 price.

I just found Siglent America has its own site, kind of hidden.  Amazon is not listed as a dealer.   I have written to Siglent asking if Amazon and AWD are authorised distributors.

[Siglent America]

Amazon is considered an authorized distributor although they don't normally have the same technical support that most other distributors do.

As long as an instrument has not been damaged, modified or abused and the calibration seal is intact then it will still have its standard 3 year warranty. Most customers who have blown out a meter or scope due to excessive input voltage, for example, have been honest about it when they first contacted us.