QA on Rohde & Schwarz oscilloscopes - Page 1
Forum section: electronics / testgear

author: fperona
author_rank: Newbie
timestamp: April 01, 2022, 11:52:54 am
content: Hello all,I had an issue with a new R&S oscilloscope and I would like to know your opinion.To make the story short, I bought an oscilloscope using this special offer (https://www.rohde-schwarz.com/de/produkte/messtechnik/oszilloskope/promotion/oszilloskope-sonderaktion_253927.html). After turning it on, I intermediately notice one damage pixel at the top left side of the screen (the pixel was always green). I contacted the distributor, and after a couple of weeks, they managed to replace the device with a new one. I received the new scope just yesterday, and I was completely annoyed when I notice that this one also has a defective pixel. This time it is in the bottom-right division, so it is another device. Now I'm wondering if just keep it and try to ignore that green point (it's quite visible) or ride again the journey across the customer service.- Have you had a similar experience with R&S equipment?This time the customer service also mentioned that three defective pixels are acceptable because it doesn't affect the functionality of the device. I have heard that in the past, but for cheap LCD screens, and I was not expecting an answer like that from a company that monetises their "excellent quality standard" with a substantial spread over a similar competitor.- Is the three pixels rule an industry standard?I'm struggling because the oscilloscope has good functionalities, and the special offer makes it very attractive and competitive. But it annoyed me the feeling that they are selling factory seconds without informing it.- What happened with other brands or devices? Is it normal to get defective pixels on a screen?Thank you for your comments!Felipe.-

author: Domitronic
author_rank: Regular Contributor
timestamp: April 01, 2022, 12:20:23 pm
content: Hello,I'm not aware of a "three pixel rule". But there is a ISO standard which defines different classes. Not sure if measurement equipment is in the scope of this standard. Usually manufacturers of displays, notebooks, TVs specify a class and customers have to tolerate the respective number of pixel errors.Here a link to the german Wikipedia page. It refers to another standard than the english version. Not sure which one is up to date:https://de.wikipedia.org/wiki/Pixelfehler

author: tv84
author_rank: Super Contributor
timestamp: April 01, 2022, 02:10:01 pm
content: Felipe,I wouldn't accept 1 bad pixel in a new 8k screen much less in a smaller than HD screen.I accept that a pixel could fail within some months. I don't accept that in such expensive device the pixel already comes bad. An alternative would be a nice discount... or a replacement.

author: 2N3055
author_rank: Super Contributor
timestamp: April 01, 2022, 06:23:26 pm
content: Quote from: tv84 on April 01, 2022, 02:10:01 pmI agree. If cheap Siglent, Rigol, Micsig can have screen with zero defects, and R&S can't, then the question is which is the premium brand then?

author: thm_w
author_rank: Super Contributor
timestamp: April 01, 2022, 09:25:56 pm
content: What model is it?Seems unusual for an old tech screen 640x480 (?) to have a stuck pixel IMO. Maybe they had to re-source or had supply issues?I'll go ahead and disagree though, 90%+ of people do not care about one or two dead pixels. If I bought R&S scopefor workand it had a stuck pixel, I would not care in the slightest.Acer for example will guarantee 2 or less stuck pixels. Dell guarantees none on their premium displays, but 2-5 stuck pixels on their regular monitors and laptops.

author: tv84
author_rank: Super Contributor
timestamp: April 01, 2022, 09:34:31 pm
content: Quote from: thm_w on April 01, 2022, 09:25:56 pmSo in your work you belong to the 90%, when you get home you cross over to the 10% group? Interesting...Is it because it's your money?

author: thm_w
author_rank: Super Contributor
timestamp: April 01, 2022, 09:54:25 pm
content: Quote from: tv84 on April 01, 2022, 09:34:31 pmExactly, not my money or property.Although would be nice for OP to provide a photo, to give us an idea of how bad it looks in normal use.

author: bdunham7
author_rank: Super Contributor
timestamp: April 01, 2022, 10:02:30 pm
content: Dead pixels on a high resolution screen, meh. A hot pixel, though, is pretty annoying. I'd be unhappy at rate exponentially proportional to the price. We went to see a movie (Dune) at a brand new IMAX theater and the screen there had a hot pixel. I thought it was was pretty amusing, and to me it stuck out prominently. Nobody else seemed to notice though.

author: 2N3055
author_rank: Super Contributor
timestamp: April 01, 2022, 10:05:46 pm
content: There is a difference when you have 1 Mpixels and 4 or 8 Mpixels. Or super high pixel density. Or very large screen where it is hard to keep manufacturing tolerances over a more than a square meter of glass.Screens on scopes are class of devices comparable to tablets. Today even cheapest 10" tablets (that cost a fraction of the money of one R&S passive probe) can be had with IPS screens with good picture quality, contrast and no dead pixels..That is why I made sarcastic remark. R&S is more expensive because it is supposedly a premium brand. We could argue that a 300€ scope with one dead pixel is something you can live with, because, well, dead cheap. And it still measures and does the job. So acceptable compromise.On something costing several thousands, where screen, frankly, should not be large part of BOM, that is something not really acceptable. Not because it will prevent you from using the scope. It won't. But because it is premium price. We get to be demanding. Otherwise, drop the price to quality level you're providing, not the one you pretend to give..

author: bdunham7
author_rank: Super Contributor
timestamp: April 01, 2022, 10:09:50 pm
content: Quote from: 2N3055 on April 01, 2022, 10:05:46 pmPerhaps that is what they are doing? If you look at the link, they have some pretty fierce discounts.A hot pixel probably isn't the worst defect a scope can have, it is just one of the hardest to overlook for some.

author: 2N3055
author_rank: Super Contributor
timestamp: April 01, 2022, 10:34:37 pm
content: Quote from: bdunham7 on April 01, 2022, 10:09:50 pmHmm you could be onto something... Those are not bad discounts for them.No, dead pixels are not show stoppers. White pixels are annoying but not showstoppers either. Many years ago pretty much all LCD screens had some dead pixels. It was accepted that process is imperfect. But today, not really, not acceptable for a premium brand.

author: nctnico
author_rank: Super Contributor
timestamp: April 01, 2022, 10:53:42 pm
content: Maybe it has to do with the part shortage that they are using screens that have a few dead pixels. Better than having nothing to sell.

author: tv84
author_rank: Super Contributor
timestamp: April 02, 2022, 09:27:45 am
content: Quote from: nctnico on April 01, 2022, 10:53:42 pmSure, as long as they adjust the pricing. I wouldn't mind having some dead pixels in a LeCroy/R&S at Rigol/Siglent prices...

author: EEVblog
author_rank: Unknown
timestamp: April 02, 2022, 10:13:36 am
content: Dead (or stuck) pixels used to be a thing in the 90's when LCD technology was still improving, and you often had to accept those as part of the sale. But this hasn't bene a thing for decades.I remember at Keycorp in the early 90's we used start of art at the time 800x600 colour LCD screens and the manufacturer would only warrant under a certain number of dead pixels. I think it was a differnt spec for stuck ones which were more annoying.

author: EEVblog
author_rank: Unknown
timestamp: April 02, 2022, 10:16:12 am
content: Ask them for a some software upgrade options as compensation!

author: fperona
author_rank: Newbie
timestamp: April 03, 2022, 01:01:17 pm
content: Hi again,Here are the pictures of both oscilloscopes, so you can make an impression. The location of the stuck pixel in the second device is easier to overlook, so at least there is an improvement in that sense. I also have tested a big part of the functionalities and apparently, the pixel is the only defect it has.Quote from: thm_w on April 01, 2022, 09:25:56 pmIt is the first one, RTC1002. Which comes fully loaded (300 MHz, waveform generator, 8 digital inputs, pattern gen and communication protocols decoding). So @EEVblog, there is no more to ask for. Maybe an extension of the warranty.Quote from: 2N3055 on April 01, 2022, 10:05:46 pmI think the same. Because one defective device can happen, but two in a row.... then it feels suspicious. In the end, there are two options: a) There is no final quality check. Because the minimum test they can do is to turn on the equipment and see the screen. Or b) they sell the rejected device in special promotions in the retail. I feel inclined to the second, of course. But at the same time, I think it is a bad practice not to make it clear as a B-ware selling.Maybe if they had been transparent from the beginning I would have bought it anyway, without feeling that I'm getting cheated. Because, although it is a good amount of money, the price is quite good. It is similar to a 200 MHz Keysight DSOX1202G but you get in addition the digital channels, highest bandwidth and double of points in the FFT.Well, thanks for the inputs, I have a more clear picture now. I will talk tomorrow with the distributor to see what can they offer.Cheers!Felipe.-

author: thm_w
author_rank: Super Contributor
timestamp: April 05, 2022, 12:25:18 am
content: Quote from: fperona on April 03, 2022, 01:01:17 pmI am certain they would do a quality check. But, on our products, I would never reject a screen for a single stuck pixel. That said I've never noticed one either... just more obvious display issues where full horizontal rows are not present or the entire screen is affected. And if customer complained I would send a screen that I actually checked was OK.The R&S screen is 6.5" 640 × 480 pixel for anyone wondering.Up to you at this point how big of a deal it is.

author: EEVblog
author_rank: Unknown
timestamp: April 05, 2022, 11:21:50 am
content: Quote from: fperona on April 03, 2022, 01:01:17 pmBummer.Those stuck pixels in the photos would really annoy me. I can't believe they'd let that slide.

author: Caliaxy
author_rank: Frequent Contributor
timestamp: April 05, 2022, 12:34:01 pm
content: I have an RTC1002 exactly as yours, bought at a heavily discounted price from a reputable US dealer (with a 6% eevblog discount on top of that) and it doesn’t have any dead pixel (or any other issue I could identify).

author: fperona
author_rank: Newbie
timestamp: May 23, 2022, 04:08:12 pm
content: Hello all,I wanted to update this post, maybe it is useful for someone.Finally, I sent the second device to the distributor (reichelt.de) and I asked for a refund. After about three weeks of silence, and to my surprise, instead of transferring the money, they sent the second device to the R&S service to replace the LCD. I receive it for the third time and guess what ..... it also has stuck pixels (see photo). So, they exchange one defective LCD with another defective LCD .... Why do they waste their time in that way? I don't know ...Now I'm stuck because Reichelt doesn't want to refund the money but give me a credit note (but I don't want to buy a single resistor from them again). Also, I contacted R&S but they insist on the excuse that some pixels are OK in an LCD.So ... I keep trying to get a decent solution.Best,Felipe.-

author: EEVblog
author_rank: Unknown
timestamp: May 24, 2022, 01:17:53 am
content: Quote from: fperona on May 23, 2022, 04:08:12 pmR&S, seriously

author: xrunner
author_rank: Super Contributor
timestamp: May 24, 2022, 01:27:40 am
content: Quote from: fperona on May 23, 2022, 04:08:12 pmThat's simply ridiculous. For this to happen twice, then for them to know (or should have known) that you were experiencing this issue and to let it go back out with againthe same issue.Who is the repair schmuck that is looking at the screen?Simply ridiculous and unacceptable.

author: james_s
author_rank: Super Contributor
timestamp: May 24, 2022, 06:25:45 am
content: I remember back when it was just expected to have a few dead pixels on active matrix LCDs but these days even really cheap panels are usually 100% defect-free. I'm surprised one, let alone two scopes came with imperfect displays.

author: tv84
author_rank: Super Contributor
timestamp: May 24, 2022, 10:59:17 am
content: Quote from: james_s on May 24, 2022, 06:25:45 am3 and counting...

author: skander36
author_rank: Frequent Contributor
timestamp: May 24, 2022, 03:08:33 pm
content: I bought a few panels this and last year for some projects from various sources (Aliexpress, Banggood, local market). They are really cheap 9-12 $, at 1024x600 or even 800x480 but none of them have dead or stuck pixels.From where did R&S found these panels ? I am curious ...In those days is an achievement to find dead pixels, may this is an added value

author: Wim_L
author_rank: Regular Contributor
timestamp: May 25, 2022, 10:40:15 am
content: Low resolution screen, and the defect is in the measurement area. That's not a good look.