50 Ohms impedance always disabled on Rigol DS2072a - Page 1
Forum section: electronics / testgear

author: breedj
author_rank: Newbie
timestamp: February 14, 2016, 02:39:06 pm
content: Can someone tell me why I cannot change the input impedance of my channels? The menu option is always disabled. Am I missing something here?Thanks in advance!

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: February 14, 2016, 05:49:02 pm
content: Are you sure you have a DS2072A and not a DS2072? I seem to remember reading about people who had the non A versions, around the time that the hack was figured out discovered an option that was supposed to enable the 50 Ohm mode, but since the non A versions do not have the hardware for it, 50 Ohm mode could not actually be turned on. Just the menu option would appear.

author: Muxr
author_rank: Super Contributor
timestamp: February 14, 2016, 05:54:33 pm
content: Quote from: CustomEngineerer on February 14, 2016, 05:49:02 pmThat would make sense, because I've never run into grayed out 50 Ohm option on my DS2072A.

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: February 14, 2016, 06:38:50 pm
content: My other thought is if breedj "upgraded" his scope, or if it was purchased used maybe the previous owner "upgraded" the scope, and used one of the codes for the non A models. I'm not sure if there really are different codes for A and non A versions, but I know (aka think) the 50Ohm is considered an option, and can be "turned off" if a code is used that does not include that option.

author: breedj
author_rank: Newbie
timestamp: February 14, 2016, 07:40:40 pm
content: CustomEngineerer. You are actually correct. I just bought the DS2072A secondhand already upgraded to 300MHz with all other options like memory, trigger, decoding, etc as well. It is now a DS2302 model.I've searched a little further and the 50 Ohm not being selectable seems to be the only downside of the upgrade, like you mentioned. So now I've to buy some impedance adapters instead. No problem of coarse.

author: Muxr
author_rank: Super Contributor
timestamp: February 14, 2016, 09:11:08 pm
content: Quote from: breedj on February 14, 2016, 07:40:40 pmMy guess is whoever did the upgrade (unlock hack) missed a step or used the wrong unlock code. Here is mine with all options unlocked.

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 14, 2016, 09:27:39 pm
content: Quote from: CustomEngineerer on February 14, 2016, 05:49:02 pmI have a non-A model that has the hardware for the 50 Ohm mode, but I never found a way to enable it.

author: Muxr
author_rank: Super Contributor
timestamp: February 14, 2016, 09:29:54 pm
content: Quote from: PA0PBZ on February 14, 2016, 09:27:39 pmThe OP has the hardware for it (the A version), but for some reason the software doesn't recognize it.

author: breedj
author_rank: Newbie
timestamp: February 15, 2016, 07:20:45 am
content: Yes, I think it has the wrong unlock code. The scope is a model A, but unlike Muxr's scope the firmware does not have an A behind the model. Is it possible to redo the unlocking? Or is there a risk in loosing the upgrades or bricking it?

author: breedj
author_rank: Newbie
timestamp: February 15, 2016, 05:52:32 pm
content: It seems that I have hardware version 1.0. I did not know about that there were two versions. So mystery solved. My version does not contain the hardware to switch to 50 ohm. So there is no need to change the firmware as well.

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: February 16, 2016, 05:10:08 am
content: If yours is actually an A version, then it does have the hardware for the 50Ohm inputs. You should go through the "upgrade" procedure, you probably don't need to uninstall the current "upgrade" first, though if you do its as easy as sending a single SCPI command.Follow the steps here:https://www.eevblog.com/forum/testgear/unlockinghacking-the-rigol-ds2000a-series-scope-the-short-post/msg759941/#msg759941Edit: Also wanted to add, there is no risk in doing this. If you manage to do something incorrectly and get an invalid license key, the scope won't take it so you will still have your current upgrades active. And if you do things correctly, but choose the wrong code, then you can always use a different code. Once you have gotten to the point of the upgrade procedure that you have your license keys generated correctly, you can freely switch between/uninstall/reinstall as many times as you want. Don't let the fact that its called "hacking the scope" scare you, its a very simple and safe procedure. Just check the last page of that thread I linked, many users (including guys completely new to the scope and scopes in general) received their scopes and had them upgraded within a few hours at most.Edit2: If you do try the procedure listed in the thread above and have any problems/questions feel free to post them in that thread. Also may want to read through that thread if you run into any issues, chances are whatever problem you may have has already been answered when someone else ran into the same thing.

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: February 16, 2016, 06:33:59 am
content: The hardware version 1.0 has been bugging me so I have been looking around at other rigol threads. It seems maybe, and I'm still not completely clear on this, but from the best I can tell, hardware ver 1.0 = non-A models, and hardware ver 2.0 = A models.breedj, how do you know that you have an A model? Does the sticker at the top of the scope have an A at the end of the model number like in Muxr's picture above? If so does it look like the sticker has been tampered with at all? Since you purchased this scope second hand it I'm assuming you don't have a warranty for the scope so it might make sense to open it up. The hardware version should be printed on the main pcb once inside. Also you could check for the actual 50Ohm hardware, my understanding is you would see a relay & 50Ohm resistor for each channel right by where the bnc connects to the pcb. I believe on the A models you would also find an unpopulated area on the pcb for the MSO hardware. If the sticker on the top of the scope does say its an A model, it could also be possible that the person that sold you the scope, originally bought non A model, then later bought an A model and swapped the guts so he could sell the non A as an A. Of course if it doesn't bother you, or you don't want to go through all this extra trouble, 50Ohm feed thru terminators are certainly an option. I'm really just hoping that the seller didn't rip you off, hopefully you paid close to what other used DS2072's are going for and didn't pay for the "upgrades" since they are so easy to do yourself. But thats between you and the seller, ultimately if you are happy with the scope and feel like you got what you paid for, then thats all that really matters.Edit: I'm still not very comfortable with my first statement, so please don't take it as fact. Maybe some non-A owners could chime in with their reported hardware versions?Edit2: Also meant to include this link to the SCPI commands to turn on and off 50Ohm termination mode if you scope has the hardware.https://www.eevblog.com/forum/testgear/rigol-ds2000-hardware-version-2-0/msg272887/#msg272887

author: Bud
author_rank: Super Contributor
timestamp: February 16, 2016, 06:50:47 am
content: 2072a has 50 Ohm feature by specification. Hardware version should not matter.

author: Muxr
author_rank: Super Contributor
timestamp: February 16, 2016, 07:11:58 am
content: Quote from: Bud on February 16, 2016, 06:50:47 amYup, I would repeat the hack procedure if I were him. It may have been one of the earlier hacks he used which didn't give him the right unlock code.

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 16, 2016, 08:20:28 am
content: Quote from: CustomEngineerer on February 16, 2016, 06:33:59 amI did but it was ignored as being irrelevant.

author: breedj
author_rank: Newbie
timestamp: February 17, 2016, 11:53:40 am
content: It was all a mistake of me. First of all I was at work creating this thread. In my mind I thought I had an A-model. That does not seem to be the case, I have a not A-model. I was confused because I downloaded the A-model User manual. I could not find the non-A model manual on the rigol site. The non-A model seems to be not existing on their site. The second thing was that, as I programmer, I learnt not to disable buttons on an interface if people are never able to use them. In the case of the Rigol firmware, they show the option but it is disabled and will never be enabled. That's a bit confusing, to me anyway. If it was hidden than it would be clear to me that the option was not on the scope.There are also some other disabled options in the firmware like sample speed and the sampling mode. I wonder if that is also because of the hardware version. These options look like a software implementation to me. As far as I know the 50 Ohm is the only difference, but I don't think they made a new hardware version just for that.Sorry about all this.