I have a strange issue of Lecroy SDA 6020, could you please help, thanks! - Page 1
Forum section: electronics / testgear

author: xbaby
author_rank: Contributor
timestamp: August 07, 2017, 01:50:49 pm
content: I have an used SDA 6020 oscilloscope, which I guess it should be similar like lecroy Wavemaster 8600?The problem is, without any input signal connected, it display some test pattern waveform as following photo (sin wave, square wave, triangle wave, and pulse for each channel) . Have you expert meet with similar issue ever? was this just a configuration issue (and how to fix this?), or was there some hardware defect (e.g., ADC or FPGA related) cause it? Thanks very much.

author: alm
author_rank: Super Contributor
timestamp: August 07, 2017, 01:57:40 pm
content: I find it hard to believe that a hardware defect would produce these signals. Looks like a textbook demo mode. Not sure how to disable it on those scopes, is there anything about it in the manual?

author: xbaby
author_rank: Contributor
timestamp: August 07, 2017, 02:07:05 pm
content: I haven't found any instruction in the manual yet. anyway I'm still not so familiar with operation of this machine as it's quite complex. thanks

author: lukier
author_rank: Unknown
timestamp: August 07, 2017, 02:33:18 pm
content: Hmm maybe it is LeCroy's internal scope? There seems to be a SW simulation mode (for LeCroy's internal use) built-in in the X-Stream software. AFAIR it can generate fake data to test things.

author: xbaby
author_rank: Contributor
timestamp: August 07, 2017, 02:38:36 pm
content: so you mean this is a simulated SDA 6020 even without real FE/ADC hardware inside? that's crazy.

author: lukier
author_rank: Unknown
timestamp: August 07, 2017, 02:45:56 pm
content: Quote from: xbaby on August 07, 2017, 02:38:36 pmWell, from what I understood from the time I was poking around the X-Stream app - yes. It seems it is possible to run the app on a standalone PC and set the HW to simulate and do other things - but this (enabling the simulation) requires special LeCroy keys in the system somewhere, probably even the hardware license dongle and enabling the developer mode to configure the model and test waveforms. I never managed to "trick" the X-Stream app to run in this mode, I always get "Not authorized to run on this platform" (i.e. missing hardware - PCI card etc).

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 07, 2017, 03:08:08 pm
content: Quote from: xbaby on August 07, 2017, 01:50:49 pmTo some extend, yes.QuoteThis is no defect, it's an internal simulation mode which produces a display of the four common standard waveforms - sine, square, triangle and pulse. This mode is normally not user-accessible so it's not clear how it was enabled on your scope.What should fix it is a removal and re-installation of the X-Stream package which should reset these settings to their defaults. So download the latest X-Stream package for your scope from the LeCroy website, uninstall the X-Stream package that is currently on the scope, reboot and then install the new package.

author: lukier
author_rank: Unknown
timestamp: August 07, 2017, 03:26:02 pm
content: Quote from: Wuerstchenhund on August 07, 2017, 03:08:08 pmOut of scientific curiosity, xbaby, can you see something related to this simulation mode in the windows registry (under Software/LeCroy) or something similar that might enable that? Or some file under C:\Program Files\LeCroy or in D:\ that could enable that?If reinstall of the app (as Wuerstchenhund) suggests doesn't help, the complete reinstall of the OS should - but in this case it is of critical importance to back-up the calibration data (D:\Calibration)!

author: xbaby
author_rank: Contributor
timestamp: August 07, 2017, 11:08:25 pm
content: thanks for all your help. I'll try to reinstall the scope software. And before that, I need to do a full disk replication for backup and further investigation of this issue.

author: xbaby
author_rank: Contributor
timestamp: August 10, 2017, 11:17:16 pm
content: Hi, all. Some updates here.I've already cloned the original disk, removed all old Leroy software and reinstall the latest version xstream software (downloaded from official website), but the issue has no change :-(So I guess it's not related with software configuration, but something in the hardware had issues. Need to further investigate. Have you some other ideas about the issue? Thanks.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 11, 2017, 05:35:35 am
content: If it's not a software problem then the most likely cause is a problem with the PCI acquisition interface card. These cards sometimes died because of overheating, usually killing some of the memory ICs on it or the FPGA itself.This is the time where it would help a lot if you had access to alternative parts for swapping and testingStrike that, when typing this I actually had a different problem (of someone else with also an SDA6020) in mindThis internal simulation is normally only available if a specific option (DEV, not to mix up with XDEV which is something different!) is installed, and this option is only available for LeCroy's developers and contracted external developers. It is *NOT* available for the normal user.Have you checked what options are installed on your scope? If you find DEV then the solution would be to just uninstall it (which you can do if DEV is installed).

author: alm
author_rank: Super Contributor
timestamp: August 11, 2017, 11:42:08 am
content: Would they really display demo signals in case of hardware failures? Are any self tests failing? Are any boards missing? Could the demo mode be switched on through a hardware jumper or persistent data (calibration)?

author: xbaby
author_rank: Contributor
timestamp: August 11, 2017, 12:51:40 pm
content: I have swapped the PCI interface card (the card with six high speed serial lane to mother board) with another working WM7300A scope, and it's confirmed the PCI card is good, and the issue is still there after swapping card. stuck again...

author: xbaby
author_rank: Contributor
timestamp: August 11, 2017, 12:55:20 pm
content: Quote from: alm on August 11, 2017, 11:42:08 amhaven't found any self test failing indication yetQuoteNo.QuoteThat's the key point I'd like to know answer or some hint.thanks.

author: alm
author_rank: Super Contributor
timestamp: August 11, 2017, 01:37:10 pm
content: I have no direct experience with these scopes, so I will definitely defer to Wuerstchenhund for that. But if I was designing a scope, I would make demo mode either:Be enabled through software (apparently not the case), as is the case with most equipment that has a demonstration mode.Be enabled through the calibration software: could it run without calibration data or with data from a different scope? Obviously values will not be accurate, but at least it might show if it starts showing real signals.Be enabled by removing the acquisition hardware (no point in putting expensive acquisition hardware in a 'display model'). That is the only way I could see a hardware failure triggering this. But I would expect self test errors if it can not reach the acquisition hardware.Be enabled through a hardware jumper. Not sure how to find those except studying the service manual if available, or visually inspecting the boards for jumpers.

author: TandMTy
author_rank: Newbie
timestamp: August 11, 2017, 02:15:12 pm
content: It for sure looks like simulation software for demonstrating the oscilloscope or simulating screenshots as I have seen these waveforms before in their marketing material. Have you tried contacting LeCroy directly? They are pretty helpful in general and can probably direct you to a solution. techsupport@teledynelecroy.com

author: lukier
author_rank: Unknown
timestamp: August 11, 2017, 02:18:12 pm
content: Quote from: alm on August 11, 2017, 01:37:10 pmI doubt there are any hardware jumpers in modern (X-Stream) LeCroy scopes, at least there are none in my WaveRunner 6100A.Removing the acquisition hardware, or just running the X-Stream app on a normal PC/virtual machine should result in a message like this:But if the SW simulation mode is enabled the PCI card detection is skipped I'd guess. I still haven't figure out how to enable such mode. I have various traces from API monitor and it seems quite complex, the software gets MAC number, HDD serial number, computes HostID, but also tries to read the HostID from the registry. There are some RPC calls related to that as well (I believe it is called LeCroy Stethoscope), as the whole app is one big DCOM-OLE interprocess mess. This is handled by the same module (and seems that in similar manner) that is responsible for options (HostID is used to compute option keys) - therefore a delicate subject on this forum, every thread discussing that in public would get removed immediately, as we've seen many times before.That's why I suggested complete OS reinstall, because reinstalling just the app might not remove some magic registry keys or files that enable this mode.

author: alm
author_rank: Super Contributor
timestamp: August 11, 2017, 03:14:25 pm
content: I missed that xbaby only reinstalled the software, not the entire OS. Then I agree that a registry key or other software setting (e.g. overriding a DLL file) is still a possibility.Could it be the demo mode is installed as an option?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 11, 2017, 03:24:25 pm
content: Quote from: alm on August 11, 2017, 03:14:25 pmThis internal simulation is normally only available if a specific option (DEV, not to mix up with XDEV which is something different!) is installed, and this option is only available for LeCroy's developers and contracted external developers. It is *NOT* available for the normal user.@xbaby: Have you checked what options are installed on your scope? If you find DEV then the solution would be to just uninstall it (which you can do if DEV is installed).

author: robert_
author_rank: Regular Contributor
timestamp: August 11, 2017, 04:23:37 pm
content: Can you look at the installed option keys (also those that are hidden, these become visible once you enter the service menu, the codes for which can be found by using google, i cant post anything related to this here)?

author: lukier
author_rank: Unknown
timestamp: August 11, 2017, 04:40:49 pm
content: Quote from: robert_ on August 11, 2017, 04:23:37 pmAt your own risk. dxl posted these codes on this forum a while ago and as you might imagine the thread doesn't exist anymore (but is still present on taptalk/google cache), so there.Which is funny because even the developer level of access doesn't let you circumvent the option system (i.e. installing options without the correct key), at best you can mess up your scope in some of the menus there. The access codes are not particularly well hidden in the XStream, contrary to the option system.I wouldn't because the EEVblog forum is too valuable and I don't want for Dave to get in trouble with DMCA and similar crap.

author: robert_
author_rank: Regular Contributor
timestamp: August 11, 2017, 05:21:00 pm
content: I wouldnt see a problem posting a screenshot or just listing something you have seen with service mode enabled.Service mode does show all options, including the normally hidden ones (such as the ones that set bandwidth or model on some scopes, normally invsible). I would expect that demo mode option to be the same. Also, service mode enables you to remove installed options (can be reinstalled without any problem, just write down the code).BTW, i never posted the service pwd here, nor did i give out any info to anybody, so please calm down. My Edit was completely unrelated to that.

author: xbaby
author_rank: Contributor
timestamp: August 12, 2017, 03:07:13 am
content: hi, all. thanks for your help. right now, I have already disassembled the scope, so it's not convenience to check the x-stream options now. I'm sure this is mainly a hardware issue, as many power rail on the motherboard have no voltage, and even one DC-DC power supply brick was removed before. I'll first tackle the power supply issue, then any software related problem or further research lately.BTW, before I disassembled the scope, I have done some experiments in the services menu. I can disable the simulation for each channel (one check box per channel). but when the simulation was disabled, there are some error messages popup, something like "acquisition board no response", "Arm failed" (not remember precisely). this phenomenon is consistent with the no power supply issue.stay tuned.

author: xbaby
author_rank: Contributor
timestamp: August 12, 2017, 04:12:47 am
content: I have attached a picture to summary the current situation of power supply issue.* PS1-PS4 are cables come from main power supply. PS1-PS3 have normal voltage, but PS4 has no voltage (0.0v). PS1 has 48v voltage to supply DCDC1 and DCDC4, so I guess PS4 should also has another (isolated) 48v voltage to supply DCDC2/DCDC3* DCDC1-DCDC4 are some DC/DC power brick with input voltage of 48v. they are all in same size and pin map. but the model number is unknown as I haven't fully taken out the mother board.so here are some question or information I need your help,1. what's the nominal voltage (48v?) and rated current of PS4, and the pin map of 4-pin PS4 socket.2. the model number and spec of DCDC1-DCDC4, especially the removed DCDC43. the nominal voltage / current of the output rail of DCDC1~DCDC44. is the mother board here same as other LeCroy scope like wp 7xxx(non-A), wm 8xxx(non-A) ?5. any ideas or similar experience are welcome.PS. I have contact with Lecroy support but they haven't given me a response.thanks very much.

author: lukier
author_rank: Unknown
timestamp: August 12, 2017, 09:45:53 am
content: Huh, I didn't realise that your scope is in such condition. It doesn't sound good, more like somebody tried to repair things in panic, removing point of load converters and such. Maybe it was the seller that enabled the simulation to fool the customer?I cannot help with this issue, as I don't have WaveMaster/SDA, maybe other forum members can chime in.Best luck!

author: alm
author_rank: Super Contributor
timestamp: August 12, 2017, 09:54:58 am
content: I am surprised that all self tests passed!

author: xbaby
author_rank: Contributor
timestamp: August 12, 2017, 10:59:02 am
content: just check my options in the services menu using developer code, there is no option "DEV" there.Quote from: Wuerstchenhund on August 11, 2017, 03:24:25 pm

author: lukier
author_rank: Unknown
timestamp: August 12, 2017, 11:08:12 am
content: Quote from: alm on August 12, 2017, 09:54:58 amWell if my theory that if simulator mode is enabled the HW is not enumerated/initialized is correct then there would be no self-tests probably.

author: xbaby
author_rank: Contributor
timestamp: August 12, 2017, 11:19:34 am
content: Quote from: lukier on August 12, 2017, 09:45:53 amThat's quite possible.I just happen to run the scope with the PCI interface card unplugged, the same unauthorized message was displayed. so I guess there were no secret switch/option to enable simulation mode on normal PC.

author: alm
author_rank: Super Contributor
timestamp: August 12, 2017, 11:21:13 am
content: If xbaby already found a way to disable simulation through the service menu, I guess that mostly solves that mystery. It seems plausible that someone enabled simulation mode to hide the hardware faults (why else would you do it?).If you can figure out the voltages and pin-outs, I would consider feeding them from a (current-limited) external power supply to see if this is a power supply issue, or if the power supply was damaged due to a short downstream.

author: xbaby
author_rank: Contributor
timestamp: August 12, 2017, 11:35:10 am
content: Quote from: alm on August 12, 2017, 11:21:13 amThat's what I'm planning, but I have no current-limited power supply on hand which can output 48v.I have measured the resistance from output of each DCDC to GND, they are all in the range of 20-30 ohm. so I guess there were no short circuit.

author: xbaby
author_rank: Contributor
timestamp: September 02, 2017, 04:28:00 pm
content: this scope is already repaired. please visit this post for detailshttps://www.eevblog.com/forum/testgear/on-board-power-supply-issue-of-lecroy-sda-6020-scope/. it's because of the xstream software can't detect the acquisition board so it automatically run into simulation mode. it's a normal feature of xstream I guess.