Rigol DS1102e issue

[kilomono]

I bought a DS1102e about a year ago. This week I used the self-calibration feature and since that time I have had a terrible problem!  Whenever I turn the oscilloscope on I see a periodic signal on the scope with a frequency of about 100 MHz. A signal appears on both analog inputs and it changes shape, but not frequency, when channel 1 or channel 2 is switched on/off. When the timescale is greater than or equal to 500 ns/div this problem manifests itself as a DC offset. The signal persists even when nothing, other than the power cord, is connected to the scope. I have retried the self-calibration and also reset the scope to the factory default settings and the problem persists. More interesting still, the waveform scales with the vertical scale; i.e. its pk-pk amplitude always appears to be about 6x the vertical scale (e.g. 1 V/div scale: 6V pk-pk amp,  10 V/div scale: 60V pk-pk amp). I have attached shots of the waveforms

I've Google searched this issue (which turned up this forum) and I've also searched this forum and been unable, in all my searching, to find a solution. I've also contacted Rigol Tech support, but haven't heard back from them yet. I'm running firmware v. 3.01

Has anybody else seen this issue? Does anyone know how to fix it?

Thanks!

ATTACHMENTS:
Figure1: Signal on channel 1; nothing connected to input
Figure2: Signal on channel 2; nothing connected to input
Figure3: Signal on channel 1 when both channels are on; nothing connected to inputs
Figure4: Signal becomes a DC offset at timescales greater than or equal to 500 ns/div
Figure5: Signal scales with the vertical scale. Note: Fig. 1 is 1 V/div, Fig. 3 is 10 V/div, Fig. 5 is 2 V/div

[kilomono]

Rigol's technical support said they had never encountered my problem and asked me to ship my scope to their nearest office. I didn't want to do that, however, so I tried some more things to fix the scope on my own. I ended up connecting a probe to channel 1 and shorting the probe to its ground clip. For some reason this idea kept pressing on my subconscious and I had to fulfill it. I ran the self-calibration with the shorted probe connected to the scope and after the self-calibration finished the problem was gone. Now I can't reproduce the problem and the scope seems to work normally. I have even tried the self-calibration feature without the probe connected (like I originally did when the issue first arose) and have had no success in reproducing the problem. I wouldn't say what I did was the solution to the problem; however, the problem is gone for now.

[Mark_O]

Cool!  Thanks for sharing your experience.

[mcinque]

Thanks for sharing, this could be useful. Just for reference: wich firmware version do you have installed?

[kilomono]

You'll see in the first post I specified that I am running firmware 3.01

[kilomono]

One more note on this issue. I very seldomly use the autoscale feature on my oscilloscope, however the phantom signal problem has very intermittently repeated itself since I "fixed it" on February 4. When I have noticed it happening again I've just pressed the autoscale button and the issue disappeared back into the recesses of the scope and out of my view.

It seems there has to be some internal signal in the oscilloscope that is bleeding over into the measurement circuitry. I have noticed that there is some correlation between the clicks the oscilloscope makes when it is changing scales (presumably relays switching states) and the persistence of the problem, but I have not yet been able to pin down and achieve repeatability of that correlation. If I ever get a second oscilloscope I may dare to dismantle this one and see what I can find out; however this scope is presently my workhorse and any downtime is a great inconvenience. I'm tempted to do a firmware update, but when I contacted tech support I was notified that a firmware update voids the warranty on the scope unless it was advised by tech support to fix a known bug. So if I update the firmware and the problem gets worse I can't be sure they'll cover it under warranty.

[Mark_O]

...when I contacted tech support I was notified that a firmware update voids the warranty on the scope unless it was advised by tech support to fix a known bug.

That's bullshit, plain and simple.  Who the hell told you that nonsense?

[kilomono]

That's bullshit, plain and simple.  Who the hell told you that nonsense?

Maybe I worded that too strongly in my post. I don't think I ever read that it voids the warranty, but it seemed like they could use it as an excuse to say my problem isn't covered under the warranty. Nobody ever said that verbatim, I just pieced it together from the document they sent me with the new firmware. What do you think?

If you choose to perform an upgrade and your unit is damaged, Rigol is not responsible
for the repair or shipping costs. The User assumes all responsibility.

Before the upgrade, please contact RIGOL Technical and Support Department to confirm
whether the current firmware version can be upgraded to the target version.

3. Important
During the installation process, please do not disturb or remove the USB drive, and make sure
the power supply is stable; otherwise, it may corrupt the firmware and cause the oscilloscope to
be unusable, and require factory support^{Note 2.}

Note 2: Service charges may be required, regardless of validity of warranty, if upgrade is not an
necessity of bugs, application failure, system feature malfunctioning.

[Mark_O]

Maybe I worded that too strongly in my post. I don't think I ever read that it voids the warranty, but it seemed like they could use it as an excuse to say my problem isn't covered under the warranty. Nobody ever said that verbatim, I just pieced it together from the document they sent me with the new firmware. What do you think?[/quote[

OK, that's a very different story than being explicitly 'told by a tech support person'.  Comments embedded below, in red.

If you choose to perform an upgrade and your unit is damaged, Rigol is not responsible
for the repair or shipping costs. The User assumes all responsibility.

Standard: if you screw up the reflash process, it's your responsibility.

Before the upgrade, please contact RIGOL Technical and Support Department to confirm
whether the current firmware version can be upgraded to the target version.

Somewhat important: with older versions of Rigol scopes (the C, and CD models at least, maybe the E and D too?) Rigol went through several different board revisions.  Each required slightly different firmware, and not all were cross-compatible.  That's why they recommend you ask first.  Putting, e.g. (made-up versions) a 2.1.17 firmware into a scope only designed to handle up to 2.1.13 could "brick it", requiring a trip to the service center to open it and fix it by reprogramming via JTAG.

3. Important
During the installation process, please do not disturb or remove the USB drive, and make sure
the power supply is stable; otherwise, it may corrupt the firmware and cause the oscilloscope to
be unusable, and require factory support^{Note 2.}

Very true: power interruptions or bumping the memory stick were probably the most likely problem scenarios, short of loading an incompatible version.  Wise not to try it during a thunderstorm. 

[Oh, and the reason this was more critical with the older 1000E series than the newer 100Z/2000/etc. is because those older models did a reflash that replaced everything, down to the base BootLoader code.  Newer models have a 2-level system, and even if the AppLayer gets hosed (what users reprogram in), the BootLoader doesn't get touched, and can recover.  So interruptions are acceptable in the newer, but not the older.]

Note 2: Service charges may be required, regardless of validity of warranty, if upgrade is not an
necessity of bugs, application failure, system feature malfunctioning.

Worthless scary comment: if newer versions of the firmware exist than you already have in your scope, the reason they exist is to fix bugs or upgrade features.  Rigol doesn't create new firmware versions for the hell of it, and users don't load them just because it's a fun activity.

Bottom line is if you load a compatible version of Rigol firmware into your scope, you're not voiding the warranty.

[TMM]

I would imagine the disclaimer is more to protect themselves against people who have goofed up the firmware flashing progress, rather than the upgraded firmware causing a problem after it was flashed successfully. Rigol don't want to have to be re-flashing everyones scopes for free when the firmware upgrade fails.