Rigol DG1022 Encoder Dial Bug - skipping

[xrunner]

Device is DG1022
Firmware 03.03.00.13.00.03.00

I have noticed a bug in the encoder dial in which it either double-steps per unit "click" or does not step up or down at certain points until you click the dial two steps. This happens in all the control menus be it amplitude, frequency, or other items where the dial is involved.

For example,

If you are at 1.00 V, you can rotate the encoder dial and find a place where it double-skips, say 1.5 goes to 1.7 in one click. Then if you go backwards you can find the place where it will take two clicks to increment the number by just 1. In this case it would be 1.4. So as you rotate the dial, it goes like this -

1.4, 1.4, 1.5->1.6, 1.7, 1.8 ...

It's not a mechanical issue, because if you notate the unit number where you are experiencing a double step or missed step, turn the device off and back on (do not touch the dial), and go to the exact same menu, the same value will still be there, but it will then increment normally, but the skips and double-steps will then migrate to other steps up the dial. If there was a bad place inside the encoder it would not be affected by turning the unit off and on.

It's like the encoder does not increment by exact units but has some uneven increment like 1.1 or something and this counter is reset when the unit is turned off. Like the count is not an integer. I know it sounds weird but it's not a mechanical problem as I've shown.

Has anyone else noticed this quirk or can verify it?  Just rotate the dial slowly in unit steps and see if it double-steps or takes two clicks to increment by 1. I have sent Rigol a bug report about it today.

[xrunner]

Rigol support says it needs to come back for repair :-(

[xrunner]

Got a call from a Rigol tech just a minute ago. He said that people have mentioned the double-skip before but no one has sent in a unit for examination. He said that ideally I was right - it should not do that, but even a new one out of the box will do it, so there is nothing "abnormal" about mine. But, it is something that does need to be addressed.

He is going to keep mine until Monday in case the product development group comes back with a quick fix, but in any case he's going to see if it can't be fixed in the firmware in a later update, since it's not a problem with the physical encoder.

 

[korjaa]

My Rigol DG1022 bought 2011 does exactly the same, very annoying to use.

It's been a while now, is anyone aware of a fix for this?

[xrunner]

My Rigol DG1022 bought 2011 does exactly the same, very annoying to use.

It's been a while now, is anyone aware of a fix for this?

I never got that unit back because they (Rigol USA) offered to give me a very good discount on a new DG1032Z. So I took that offer and was satisfied. 

[TurboTom]

The problem doesn't seem to be limited to the DG1000 series; my DG4000 shows the same behaviour. And I've heard of others reporting it. It's related to Rigol erroneously programming the "advance" of the encoder counter on the wrong phase change. The encoders used (on average) have two phase changes from one detent to the next. One line changes phase approximately half-way between the detents and the other approximately at the detents. As it seems, Rigol used the latter line for advancing the counter, and due to mechanical tolerances of the encoders, this causes the observed problem.

The encoders are decoded in a Lattice CPLD located on the Keypad PCB that apparently cannot be updated via the USB firmware update method - thus the issue can only be fixed by either replacing the keypad PCB, or possibly if Rigol would provide the users with a revised CPLD config file to be flashed into the chip (provided the user has the experience and the equipment to accomplish that task). Alternatively, a modified encoder might solve the problem. I experimented with tweaking the detent spring a little with some success, but chances are high to damage the encoder completely during such an attempt.

So actually, unless Rigol addresses the problem, there's little one can do about it. Looking back at the times when Rigol offered all users of the troubled DP832 PSUs with the "hot" voltage regulators (as identified by our host) a replacement board for being swapped in "DIY", this encoder problem doesn't seem to be severe enough for Rigol to take corrective action. Maybe on more recent units, the problem has been solved already. I've got to admit, I didn't contact them to get the issue solved, and now my DG4000 is long out of warranty.

[korjaa]

I never got that unit back because they (Rigol USA) offered to give me a very good discount on a new DG1032Z. So I took that offer and was satisfied. 

Probably a good call

[korjaa]

The problem doesn't seem to be limited to the DG1000 series; my DG4000 shows the same behaviour. And I've heard of others reporting it. It's related to Rigol erroneously programming the "advance" of the encoder counter on the wrong phase change...

Quite interesting. I wonder if a replacement knob could be changed/fabricated instead of fixing the software.