EMRFD Message Archive 3694
Message Date From Subject 3694 2009-10-30 11:56:14 chrisethompson USB Oscilloscope
It worked fine for about an hour when I got it back. Now it's broken again. Same issue. The scope was not even connected to the circuit when it stopped working.
Have others used and had issues with a USB scope? Does RF get into it and cause issues with the power supply? I'm about ready to buy a new non USB scope, but it seems a shame. It worked fine for about 4 months.
Chris
W2/G0KLA3696 2009-10-30 12:02:37 chuck adams Re: USB Oscilloscope
>I have 3 USB scopes and haven't had any problems with them.
> I'd like to check if others in this group have used a USB oscilloscope
> for RF work. I have a Link Instruments MSO 19 and it's giving me
> trouble. It stopped working a week ago. The blue power-on light did
> not come on. I sent it back to them and they fixed it very quickly for
> free. They said something about being "fuses" inside and that they
> sometimes get blown by the USB port.
>
> It worked fine for about an hour when I got it back. Now it's broken
> again. Same issue. The scope was not even connected to the circuit
> when it stopped working.
>
> Have others used and had issues with a USB scope? Does RF get into it
> and cause issues with the power supply? I'm about ready to buy a new
> non USB scope, but it seems a shame. It worked fine for about 4
> months.
>
> Chris
> W2/G0KLA
>
>
At what power levels are you working? The scopes do have a
relatively low peak-to-peak input restriction on the order
of 35V. Since you brought up the issue, I may take the
one that I have not used at all in over a year and reverse
engineer it, just to get an idea of how they did it.
"No servicable parts inside. Do not open. ... "
Of interest is just how much front end protection they
did provide. As you know, it is impossible to get the
schematics and block diagram of the internals. They
truly are 'black boxes'.
chuck3698 2009-10-30 12:21:02 chrisethompson Re: USB Oscilloscope
A quick check of the internet shows that others have had similar issues. The scope is not isolated from the computer, which is in turn connected to the earth of the mains. If this is at a different potential to the earth of your circuit then damage can result to both the scope and the computer. Maybe I am lucky my laptop was not damaged.
Chris
3699 2009-10-30 12:33:01 Jonathan L. Polan... Re: USB Oscilloscope
>I have one that works FB. Never had a problem. I am concerned by the
>
> I'd like to check if others in this group have used a USB oscilloscope
> for RF work. I have a Link Instruments MSO 19 and it's giving me
> trouble. It stopped working a week ago. The blue power-on light did
> not come on. I sent it back to them and they fixed it very quickly for
> free. They said something about being "fuses" inside and that they
> sometimes get blown by the USB port.
>
comment that the fuses might have been blown by the USB port. Is it
possible that you are connecting the scope through a USB hub that isn't
powered and is drawing too much power from the hub? I could see that
causing problems. My scope draws too much power for a single USB port
and comes with a USB cable that has 2 connectors on the computer side.
Both need to be used.
Or perhaps you have some other USB problem.
jon N0WL3700 2009-10-30 12:33:36 tetranz Re: USB Oscilloscope
I'm interested in buying something like this. Somehow I missed the MSO 19 when I was searching around recently. It seems like the best value for money if it lives up to the brochure although Chris' experience makes me a little nervous.
Are there other similar products I should look at?
Thanks
Ross KB1KGA3701 2009-10-30 12:38:56 chrisethompson Re: USB Oscilloscope
Chris G0KLA
3702 2009-10-30 12:40:13 chrisethompson Re: USB Oscilloscope
Chris
3703 2009-10-30 12:48:36 chuck adams Re: USB Oscilloscope
>http://www.alikaelectronics.com/
>
>
> Hi all
>
> I'm interested in buying something like this. Somehow I missed the MSO
> 19 when I was searching around recently. It seems like the best value
> for money if it lives up to the brochure although Chris' experience
> makes me a little nervous.
>
> Are there other similar products I should look at?
>
> Thanks
> Ross KB1KGA
>
>
>
The above is a link someone sent to me. I have the
DSO-2150 and DSO-2250 and both have worked well for
me. But I'm not a serious experimenter like many in
this group. I dabble and tinker a lot.
This would be a good starting point for pricing info.
IMHO.
Hope this helps.
chuck3704 2009-10-30 20:01:26 Stephen Wandling Re: USB Oscilloscope
http://www.taomore.com/. I just looked on their site and the DSO-2250
is $305 (up about $15 in the year) and shipping would probably be about
$30-35. Steve found that their delivery was very quick.
My question is in regards to USB 2.0 vs 1.0. I have an older Pentium
III, 500 Mhz box with 1Gb of memory, and USB 1.0. Is this going to be a
bottle neck for me? Would installing a USB 2.0 card solve the problem?
Thanks
Stephen
VE7NSD
chuck adams wrote:
> On Fri, 2009-10-30 at 19:33 +0000, tetranz wrote:
>
>>
>>
>>
>> Hi all
>>
>> I'm interested in buying something like this. Somehow I missed the MSO
>> 19 when I was searching around recently. It seems like the best value
>> for money if it lives up to the brochure although Chris' experience
>> makes me a little nervous.
>>
>> Are there other similar products I should look at?
>>
>> Thanks
>> Ross KB1KGA
>>
>>
>>
>>
> http://www.alikaelectronics.com/
>
> The above is a link someone sent to me. I have the
> DSO-2150 and DSO-2250 and both have worked well for
> me. But I'm not a serious experimenter like many in
> this group. I dabble and tinker a lot.
>
> This would be a good starting point for pricing info.
> IMHO.
>
> Hope this helps.
>
> chuck
>
>
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>
>3705 2009-10-30 20:16:58 Andy Re: USB Oscilloscope
fuse. That shouldn't have prevented the whole thing from powering up.
Seems more likely they have a fuse on the DC power line from the USB,
and yours is tripping it. If you overdrove an input, you might make
that input go dead, but not the whole unit.
Is there any chance your laptop's USB port is putting out the wrong DC voltage?
Unfortunately, from what I've heard, all these USB scopes are Chinese
imports, and probably low reliability, lacking good engineering that
would make them higher quality. Nice if they work OK, but not so nice
when they don't. Are there any American or European companies that
make them?
The problem with connecting the probes to a point other than ground in
your circuit, is common to all scopes, unless you have a differential
probe or use two probes quasi-differentially and figure out what to do
with the instrument's ground. But I don't know if it would actually
damage your laptop, unless it was a high power circuit you were trying
to probe. Yes you do run that risk, just as you might damage a $50K
Tek scope by doing the same thing. Always important to THINK about
what your "grounds" are doing before you connect anything.
Andy3706 2009-10-31 08:50:21 John Shepherd Re: USB Oscilloscope
The User Manual states that it supports USB-2.0 and 1.0. It works on Windows
98/ME/2000/XP/Vista, needs 128 MB memory and a graphics card, MS DirectX
supported with screen resolution 800X600 and color depth 16 bit. It
supports plug-n-play with 12Mbp communications speed.
Hope this helps.
John
VA3AAD
3707 2009-10-31 08:50:33 John Shepherd Re: USB Oscilloscope
infrequently for group demos.
http://www.hantek.com.cn/english/produce_list.asp?unid=64
It came with no circuit diagram and minimal instructions, but I have had no
problems with it.
Does it look like your Link device?
The manual lists "Input Protection" as 35Vpk (DC + peak AC) < 10 kHz without
external attenuation.
John
VA3AAD
3713 2009-10-31 11:48:26 Stephen Wandling Re: USB Oscilloscope
Thanks
Stephen
VE7NSD
John Shepherd wrote:
> I have the DSO-2250.
>
> The User Manual states that it supports USB-2.0 and 1.0. It works on Windows
> 98/ME/2000/XP/Vista, needs 128 MB memory and a graphics card, MS DirectX
> supported with screen resolution 800X600 and color depth 16 bit. It
> supports plug-n-play with 12Mbp communications speed.
>
> Hope this helps.
>
> John
> VA3AAD
>
>3720 2009-11-02 14:43:48 chrisethompson Re: USB Oscilloscope
http://www.linkinstruments.com/mso19.htm
I called them up (they are in New Jersey luckily and not China) and spoke with one of their engineers. He had fixed my scope when it went in for repair previously. Apparently last time the 350mA 5V fuse was blown, but so was the USB chip. Usually the scope is able to shutdown fast enough to protect the chip, he said. Of 500 repairs, this is only the second time he has seen this. Well, it looks like I am about to send the scope back in and show him a third time. Luckily they are going to fix it again under warranty.
He said that most likely the circuit had a different ground potential to the laptop and asked me to measure it.
It also seems that running the laptop on batteries is a sensible approach in the future to avoid these types of problems. He talked about various isolation schemes that they have been considering (including wireless USB), but if the scope has a power supply, such as a USB hub, then it can always be a potential problem.
I have to say, that despite these problems (which don't seem to be comm