Siglent SDS804X HD - No USB Power From Scope ? *Got Power But Trips Port*

[TomKatt]

I recently procured a Micsig DP10007 Differential Probe (older model) that requires a 5V USB power source.  I assumed that one of the two USB jacks on my SDS804X HD scope would work as a power source for the probe, but it fails to run when plugged into  either USB jack on the scope.  The probe powers up correctly when plugged into a USB AC adapter.  The probe spec sheet indicates it only requires 1.25W of power, so I can't believe that the USB jacks on the scope are limited to less than that.  I tried two different USB cables and neither worked with the scope.

I know the USB ports on the scope work as I have used usb drives to transfer files and update the firmware and did not encounter any issues.

Is there a 100ma power limit on the scope USB ports?  1.25W should only be about 250ma, which I would have expected to be sufficient.

EDIT - After testing again with a thumb drive, initially the drive was not detected.  I power cycled the scope at which point the usb drive was detected and I was able to browse the drive through the file manager on the scope.  I then swapped the thumb drive with the differential probe and it powered up normally.

Very strange.

[TomKatt]

There's definitely something wonky going on here - not sure how I managed to get the probe to power up once, but now every time I plug the probe into the scope it fails to power up.  Occasionally I can see the trace drop in cycles as though the probe is attempting to fully power up, but it never does.  Once I plug the probe into the USB port for power (and it fails to power up), if I then plug the thumb drive into the scope it does not detect it any longer.  Power cycling the scope appears to reset the USB port and the thumb drive is once again recognized.  But as soon as I plug the probe into the scope it's as if the probe trips some current limit and it seems to shut down the USB ports until the scope is power cycled.

For now, I'm going with the premise the the Micsig DP10007 probe requires more current than the scope can provide.  That still seems odd as I believe I have seen numerous videos of this probe being powered by scopes online.  I have an SDS1104X-E at work and I'll try this probe on that scope tomorrow.

EDIT - I always wanted to get one of those cheap USB power analyzers anyway...  I'm very curious how much current this differential probe draws...  There's not much to it - I'd be surprised if it took more than the 500ma USB 2.0 is rated for.

[tautech]

There's definitely something wonky going on here - not sure how I managed to get the probe to power up once, but now every time I plug the probe into the scope it fails to power up.  Occasionally I can see the trace drop in cycles as though the probe is attempting to fully power up, but it never does.  Once I plug the probe into the USB port for power (and it fails to power up), if I then plug the thumb drive into the scope it does not detect it any longer.  Power cycling the scope appears to reset the USB port and the thumb drive is once again recognized.  But as soon as I plug the probe into the scope it's as if the probe trips some current limit and it seems to shut down the USB ports until the scope is power cycled.

For now, I'm going with the premise the the Micsig DP10007 probe requires more current than the scope can provide.  That still seems odd as I believe I have seen numerous videos of this probe being powered by scopes online.  I have an SDS1104X-E at work and I'll try this probe on that scope tomorrow.

This.

Normal behaviour for a heavy USB load at boot.
Try other USB powered devices as you might find a sweet spot that when exceeded shuts down USB supply when booting.
IIRC after boot, 500mA was the trip point.

[Martin72]

Hi,

It sounds to me that the differential probe has an inrush current that is too high (for the scope).
The differential probe contains switcher circuits that process other voltages from 5V and these switcher supplies could have an initially “high” inrush current.
This will be very short, but possibly too long for shutdown detection.

[TomKatt]

Yes, both these replies align with my thoughts as well.  I powered the probe from my Siglent SPD1305X linear power supply and although the display isn't quick enough to display the inrush current, it hits 219ma (1.095W @ 5V) almost immediately.  So there must be some caps getting charged in the probe at power up that push things over the limit.  I'm a bit surprised that this is enough to trip the scope ports, but I guess I'd rather they are well protected instead of something damaging the more expensive scope.

Thanks for the input!  I should run the power through my multimeter set to peak ma just to satisfy my curiosity...

[Martin72]

It would be better to do this with a current clamp and oscilloscope.
I could do it, but unfortunately I have sold my Micsig DP probe.

[tautech]

Yes, both these replies align with my thoughts as well.  I powered the probe from my Siglent SPD1305X linear power supply and although the display isn't quick enough to display the inrush current, it hits 219ma (1.095W @ 5V) almost immediately.  So there must be some caps getting charged in the probe at power up that push things over the limit.  I'm a bit surprised that this is enough to trip the scope ports, but I guess I'd rather they are well protected instead of something damaging the more expensive scope.

Thanks for the input!  I should run the power through my multimeter set to peak ma just to satisfy my curiosity...

Another purchase may be necessary to properly quantify initial peak current.......it's called a current probe ! $ $ 

Careful, it's another rabbit hole.

[TomKatt]

Another purchase may be necessary to properly quantify initial peak current.......it's called a current probe ! $ $ 

Careful, it's another rabbit hole.

LOL - I have an older Amprobe CT237B with banana plug leads that has 20A/200A ranges, but it might not be sensitive enough for such low current.  I've been considering something for lower current measurements, but don't often need to scope it out.  I'll have to poke around for suggestions - the Hantek CC65 is dirt cheap and supposedly goes down to 20ma, but you get what you pay for.

Thanks for the advice ;-)

[tautech]

You might get away with a shunt.....just be careful how/where you attach the probe reference lead.....not difficult for this particular need, given a little thought. 

[mawyatt]

Tom,

Just tried with our DP10007 and SDS800X HD without any problems, even tried using a cheap Yuanxin USB extender port (3) which has a Mouse Wireless USB also plugged in, with same results.

Scope boots up fine and can plug unplug DP without any issues.

Seems somethings not behaving with your items?

Best,

[TomKatt]

Tom,

Just tried with our DP10007 and SDS800X HD without any problems, even tried using a cheap Yuanxin USB extender port (3) which has a Mouse Wireless USB also plugged in, with same results.

Scope boots up fine and can plug unplug DP without any issues.

Seems somethings not behaving with your items?

Best,

Yes - I do think something is amiss.  Hopefully it’s the probe and not the scope.  I’ll try the probe on my other scope tomorrow and see what happens.  Although my meter isn’t fast enough to capture the complete spike, it still only registered a max of 264ma, which shouldn’t cause any issues.  But it's obvious the scope is NOT happy trying to power up the probe.  Finding another power source is a lot easier than trying to RMA the scope, which works perfectly in every other respect.  We’ll see how things progress.

Thanks for your input !

Edit - I've got more faith in Siglent than the Micsig probe lol.  I also just plugged a wired mouse into the scope and it works perfectly.  Granted the mouse probably uses less current, but still enough for an led, camera, ucontroller etc.  Nevermind - the mouse peaks at 25ma and immediately drops to 3ma...  A lot more power efficient that I'd have expected.

[Martin72]

Hi,

*Resolved*

And what is the solution now?

[TomKatt]

Hi,

*Resolved*

And what is the solution now?

Well, I've got power and the scope appears to be working correctly.... I didn't want to leave a post up inferring otherwise.

But you are correct - further investigation is needed and will continue.  I should have phrased that differently (done).

[TomKatt]

OK - now I'm a bit nervous...  Plugged the DP10007 probe into my SDS1104X-E and it immediately powers up and works exactly as it should.   So, my new SDS804X HD scope looks like it's overly sensitive for some reason.  As best I can tell, the probe only spikes no more than 300ma at power up and almost immediately falls to ~200ma - that should not be an issue.

I'm not sure if it's worth going through a warranty process for this as I have discarded the original shipping carton and realistically I can just use a dedicated power supply for the probe, which I use infrequently anyway.

Would anyone have ideas to better test this?  I'm trying to think of some USB devices that should work with the scope that consume more current than a mouse or keyboard, as those low power items work correctly...   Perhaps a portable spinning hard disk?  I don't have a low power current probe - I've only tried running the usb power through my BM235 multimeter set to capture min/max/avg.

Edit - should also mention that whatever 'circuit breaker' trips on the SDS804X HD affects both front and rear USB ports.  Tripping one with the probe shuts down both ports.

[pdenisowski]

You're overlooking the holy grail of T&M:  the opportunity to use a T&M instrument to troubleshoot itself ....   

But in all seriousness: a USB load tester like this might help

https://www.amazon.com/DROK-Electronic-Adjustable-Intelligent-Temperature/dp/B07FL3PS57

[TomKatt]

Yes - every troubleshooting task is an opportunity to expand the lab lol ;-)

I've already ordered a FNIRSI usb meter - I've been wanting one for a while but other gear was always prioritized...

[pdenisowski]

I've already ordered a FNIRSI usb meter - I've been wanting one for a while but other gear was always prioritized...

Oohh ... fancy!  Looks like this forum just cost me another 50 bucks

[TomKatt]

I've already ordered a FNIRSI usb meter - I've been wanting one for a while but other gear was always prioritized...

Oohh ... fancy!  Looks like this forum just cost me another 50 bucks

More pixels = more betterer 

But the biggest thing is that I believe this tester allows for a separate pc monitoring connection outside of the source and supply ports.  I'll need something like this because as soon as I test the probe it's going to trip the USB port on the scope, which would otherwise shut down the meter as well, rendering the test useless.

I'll probably end up getting a current probe as well - still leaning towards the Hantek CC65 given it's price & features.  Reviews show this probe has a bit of a drifting issue, but given my infrequent need it's probably the best bang for the buck.

[TomKatt]

You might get away with a shunt.....just be careful how/where you attach the probe reference lead.....not difficult for this particular need, given a little thought. 

Has anyone ever tried using the shunt inside a multimeter?  Like if I use the meter inline on the ma setting and then use the scope to probe both sides of the meter jacks?  I could perhaps use 2 scope channels with math difference between the two if I test the positive rail, or perhaps if I shunt the negative rail (which should be scope ground) then I could use a single channel on the DUT side of the meter shunt?  Obviously cannot connect channel ground to any portion of the positive rail ;-)

I'll have to poke around to see if any meters spec their shunt resistances... 

[KungFuJosh]

This one has Bluetooth: https://www.amazon.com/dp/B0CWLM4159/ 😉

[Martin72]

Oohh ... fancy!  Looks like this forum just cost me another 50 bucks

The forum just cost me €16:

USB Cable Tester

 

[watchmaker]

OK - now I'm a bit nervous...  Plugged the DP10007 probe into my SDS1104X-E and it immediately powers up and works exactly as it should.   So, my new SDS804X HD scope looks like it's overly sensitive for some reason.  As best I can tell, the probe only spikes no more than 300ma at power up and almost immediately falls to ~200ma - that should not be an issue.

I'm not sure if it's worth going through a warranty process for this as I have discarded the original shipping carton and realistically I can just use a dedicated power supply for the probe, which I use infrequently anyway.

Would anyone have ideas to better test this?  I'm trying to think of some USB devices that should work with the scope that consume more current than a mouse or keyboard, as those low power items work correctly...   Perhaps a portable spinning hard disk?  I don't have a low power current probe - I've only tried running the usb power through my BM235 multimeter set to capture min/max/avg.

Edit - should also mention that whatever 'circuit breaker' trips on the SDS804X HD affects both front and rear USB ports.  Tripping one with the probe shuts down both ports.

I just tried my DP 10013 in my SDS824 using the Siglent supplied USB cable to connect to the A connector on the probe.  Both the rear and the front USB ports provide power no problem.  Latest scope FW.

Also worked with my 1204.

[TomKatt]

Oohh ... fancy!  Looks like this forum just cost me another 50 bucks

The forum just cost me €16:

USB Cable Tester

 

I've gone down rabbit holes numerous times because a usb cable looked ok but was either damaged or was one of those evil 'charging cables' that lacked data lines...  Might as well add it to the shopping cart 

[TomKatt]

I just tried my DP 10013 in my SDS824 using the Siglent supplied USB cable to connect to the A connector on the probe.  Both the rear and the front USB ports provide power no problem.  Latest scope FW.

Also worked with my 1204.

Thanks!

It would seem that the problem is in my new SDS804X HD scope...  At this point I'm just working through the issue to satisfy my curiousity but I doubt there's anything I can do to resolve it short of trying to RMA the scope, which is probably more of a hassle than anything.  Though I'll always wonder if this is some kind of indication of future issues down the road - a difficult decision.

[TomKatt]

And the mystery continues 

Got busy and left the DP10007 probe running on my SDS1104X-E all day.  Brought the probe home and figured I'd just see what happens with my SDS804X HD...  It powered right up no problem.  Unplugged it and plugged it back in several times, works fine.  Powered off the scope and rebooted - works fine 

The DP10007 probe is new, but old stock - I think it was produced in 2022 or earlier and yesterday was the first time it was powered on since it was shipped from the factory.  What are the odds that some power supply caps went a bit south and running it for 8 hours gave them an Italian tune-up or something?  I know that capacitors shouldn't fail like that in just a few years, but with some of the cheap components these days I wonder.

Anyhoo, things are looking good and I ended up ordering some new test gear in the process.  I've had worse days 

Edit - now that everything is operational I got the chance to use the DP10007 on the vacuum tube scope I'm working on.  I know the DP10007 has some CMRR issues from Dave's investigation, but for my use at frequencies <100KHz it actually seems to work quite well, and definitely a lot safer than standard probes in several hundred volt circuits.  For the price I paid, it's a bargain