1 3 4 5 6 7 231 Replies Latest reply on Sep 25, 2012 5:22 AM by Roger Wolff Go to original post
      • 60. Re: RG1 1.8v regulator

        . I'd love one of those IR cameras though... They'd be a bit harder to find in someones junk bin.

        Definately... I even went and looked at prices for a new one

        • 61. Re: RG1 1.8v regulator

          I think the argument "you get what you paid for" is very lame,

          Possibly true.  My take on it is that something that's agressively designed down to a very low cost inevitably leads to compromises, doesn't matter if it's the RPF or IBM.  You have to account for that somehow and expecting the same results as something designed to a 10x greater cost with a huge R&D budget behind it just isn't realistic.

           

          We may not like all the compromises, but it's done now. Hopefully a potential version 2 can improve things.

          • 62. Re: RG1 1.8v regulator

            "Our perfect and faultless design is now even more perfect and faultless!".

            That particular aspect of the mantra is one that really annoys me. Especially when Pete comes here with the 'flaws and fixups' thread and seems quite open that there are issues he's looking at.

            • 63. Re: RG1 1.8v regulator

              If they were wanting to

              find bugs and mature the product, they would have a highly visible

              bug tracking system,

              Yeah, it's long past the point where the blog and forum format outlived it's usefulness - I'd argue mid April when the first boards were delivered was when it should have changed. The Raspbian site makes them look so much better and they probably have less people and resources, so it's not hard.

               

              Jamodio ought to be a hero on the RPi forum for finding what is probably

              the most serious design error. 

              Agreed. I haven't looked recently, but I noticed that they basically just blanked him when he posted it which, to me, says a lot.

              • 64. Re: RG1 1.8v regulator
                Tooms

                Troy Mackay wrote:

                 

                Tooms wrote:

                 

                i will love to try out the hack Troy mackay has done also and then test again with that fix on the board, but i have looked into this and i most say it is very well done by Troy as i think it is to small for me todo and i done have an microscope as need for this.

                 

                so yes if some one can findout where to make an cut to split the LAN9512 1v8 from the lod 1v8 then i will try this also.

                 

                 

                Tooms

                The microsope is really handy (and didn't cost me a cent), you'd be surprised what you can do when you can see what it is you are doing. I haven't even done a lot of SMD work. I'd love one of those IR cameras though... They'd be a bit harder to find in someones junk bin.

                 

                Hi

                 

                yes i am only having an magnifying lamp the glass ones with 40 leds and it is not very good so i have been missing this for an long time..

                 

                I ask my local hacker space if they hade an good microscope but they only got an older fix one, have not seen it.. so i have now my own microscope on the way and hope it will be here in 7 days time and then i can try do the hack you have done..

                 

                I can see you only have split the VDD1V8CORE but what about the other VDD1V8ETH and VDD1V8USB ?

                 

                 

                Tooms

                • 65. Re: RG1 1.8v regulator
                  Tooms

                  selsinork wrote:

                   

                  My IR thermometer arrived yesterday

                  I was looking at picking one up, but noticed that even rather expensive ones seem to have a minimum measurement 'spot' of something around 20mm which is rather larger than the lan9512. I was wondering just how that affects the readings..  Presumably they average the total emissions over whatever is in the sensors view somehow.

                   

                  Like you I don't have a Pi that runs as hot as some reports, and without one it's difficult to form a theory on what the cause is.

                   

                  yes the IR meter have there issues and you have to know it to get good readings and i have even an very good Fluke 568 there is on the high side of them and i dont use muchs because they crude in eletronics work and it is better to use an IR cam

                   

                  The Fluke 568 IR meter i am having is having and IR spot of (the number is is IR spot size and the distance from the surface)

                  Spot 19mm @ 300mm distance

                  Spot 18mm @ 900mm distance

                  Spot 42mm @ 1500mm distance

                   

                  you also has to hold it at an right angle

                   

                   

                  next time i will do some testing i will take both some IR images and use the IR meter and let you know what it is showing, but in the mean time try look at the images i have posted there is an graf showing the temparatura across the surface of the chip and you can clearly see the edges of the chip and that there is an very tinny hotsport at the center of the chip.

                   

                   

                  Tooms

                  • 66. Re: RG1 1.8v regulator

                    it is better to use an IR cam

                    I'd love one.. I looked at prices. No way can I afford one

                     

                    The Fluke 568 IR meter i am having

                    Yeah, that's the one I was looking at, it was the only one I could find that gave a good explanation of the D:S relationship and that was what decided me not to bother getting one - my dodgy sensor stuck to the top center of the IC is likely more accurate

                    • 67. Re: RG1 1.8v regulator
                      PeteL

                      Hi

                       

                      If it has a different signal name it is not connected to the 1V8 plane.  Like most good CAD systems it does 'mostly' what it's told.

                       

                      I've been travelling again and not been able to get to my lab but I'm now in 'full' duplex conversation with Microchip (ex:SMSC).

                       

                      I see the issue with 'higher' temp but now I get the feeling you are looking to fix something else with this mod?  Can you confirm?  There is mention of the USB issue - point me at it please and anything else you think is connected.

                       

                      Cheers

                       

                      Pete

                      • 68. Re: RG1 1.8v regulator
                        PeteL

                        Has anyone found the emissivity coefficients that we should use for the encapsulant on the chip (0.92 has been suggested)?

                         

                        I've asked a few chip suppliers FAEs and been met with a blank stare!  I guess that's why I still use thermocouples, but they are messy as I always gunk them up with heatsink compound.

                         

                        Cheers

                         

                        Pete

                        • 69. Re: RG1 1.8v regulator
                          Tooms

                          Hi

                           

                          I am using the 0.95e on my Fluke 568 as this is the default one and it is for black plastic

                           

                          the 568 build in tabel has:

                          0.93 paint

                          0.95 plastic

                          0.93 water

                           

                          an book i have about IR is having

                          0.85 Brick, common

                          0.94 Brick, refractory rough

                          0.95 electrical tape black plastic

                          0.92 Glass

                          0.93 lacquer, bakelite

                          0.94 paint average oil based

                          0.94 paper black

                          0.93 rubber

                          0.92 tar paper

                           

                          (I have only listed the values there seems usagbol to this as the list is alot longer..)

                           

                          So based on this i will say around 0.93-0.95 so a good point will be 0.94e but as other users here is having IR meters and they are very likly fixed at 0.95e so i think it is best to use 0.95 so it is easyer to compire the results there is posted.

                           

                           

                          Thomas

                          • 70. Re: RG1 1.8v regulator
                            jamodio

                            coder27 wrote:

                             

                            Jamodio ought to be a hero on the RPi forum for finding what is probably

                            the most serious design error.  Instead, he is banned as a concern troll.

                             

                            I don't think I have to be considered a hero, somebody else would have noticed and reported the error(s) if RPF had released the schematics and Gerbers before sending the boards to production.

                             

                            There is another major issue with the quality of some of the components as I reported before. In particular the LDO voltage regulators that on the beta board were from NXP and now are from some Chinese knock off.

                             

                            In my company we are moving away from buying some cheap components produced in China, it is well known in the electronics community that counterfeiting of components have been increasing substantially, like one of the more known cases being the Nichicon aluminium electrolytic blowing up on monitors and computer switching power supplies since the counterfeit part used a very low quality dialectic and the part does not meet the specs.

                             

                            To tell the truth this is not a complex board in number of parts, signals, nets, and we engineers often make errors, that's why when we work professionally we have a review process before we commit to large scale production. In this case the process didn't exist or some people were not paying attention.

                             

                            What really concerns me (after all I'AM a "concern troll") is that this type of situation serves as a learning experience so we don't repeat the same errors or wrong processes, but I doubt that if there is ever a new revision or version of this board, we'll have the opportunity to review it before the hype-pi 2.0 starts.

                             

                            My .02

                            -J

                            • 71. Re: RG1 1.8v regulator
                              PeteL

                              Seems like a good suggestion - as you say at least we can compare results with some confidence, I think the issue on resolution, spot size is also a complicating factor.  From what I understand you will get the average of the spot size so any real hot spots will be averaged away.

                               

                              I've been trying to find a IR lens that will give 10mm x 15mm as the total field of view.  Interestingly it gets even more complicated when you look at effective touch temperature and we need a gizmo called a "thermesthesiometer probe" but these are not commercially available as far as I have found - if you find one let me know.

                               

                              NASA (slightly old but the most recent I could find) have suggested that 45C is tolerable (indefinitely) for polished metal with an effective infinite heat capacity, and obviously a very high thermal conductivity, but this does not play well to our circumstances unless we measure less than that.

                               

                              So I think there are three issue in this thread:

                               

                              1) Touch temperature concern.

                              2) Die temperature and effect on performance.

                              3) Effect on functionality of USB? (Circumstances yet to be determined)**.

                               

                              I have not seen any reports that making the suggested mod fixes anything, I'm sure you will let me know if I've missed it.

                               

                              As always - comments welcome.

                               

                              Cheers

                               

                              Pete

                              • 72. Re: RG1 1.8v regulator
                                In my company we are moving away from buying some cheap components produced in China, it is well known in the electronics community that counterfeiting of components have been increasing substantially, like one of the more known cases being the Nichicon aluminium electrolytic blowing up on monitors and computer switching power supplies since the counterfeit part used a very low quality dialectic and the part does not meet the specs.

                                I must have replaced thousands of those in PC's, but that particular problem seems to be solved - at least from what I see.

                                 

                                From the people I know who work for chinese manufacturers it certainly appears that a large part of going to china is to do with getting counterfeit parts - if not the whole device!

                                Part of the problem is quickly going to become - if it hasn't already - that your 'original' NXP LDO will have been made in the same factory, on the same equipment, and to the same design as the chinese one. Maybe both will use the NXP design, maybe the chinese one. As long as they're not totally flaky and outlast the warranty there's a part of me that thinks nobody will care - stuff dying sooner means you replace it sooner and someone makes another sale. The beancounters like that idea

                                 

                                Have we all seen this before ?

                                chinese-capacitor.jpg

                                I have no idea if it's real or someone just did a mockup to illustrate a point, but certainly made me smile

                                • 73. Re: RG1 1.8v regulator
                                  morgaine

                                  jamodio wrote:

                                   

                                  What really concerns me (after all I'AM a "concern troll") is that this type of situation serves as a learning experience so we don't repeat the same errors or wrong processes, but I doubt that if there is ever a new revision or version of this board, we'll have the opportunity to review it before the hype-pi 2.0 starts.

                                   

                                  +1.

                                   

                                  Feedback on issues is part of the engineering process.  That's alien to Liz's hype & fandom process.

                                   

                                  PeteL wrote:

                                   

                                  As always - comments welcome.

                                   

                                  +1

                                   

                                  I've been trying to quantify one particular area of faulty operation, RF mice on self-powered USB hubs .  With dozens of tested (device X hub) combinations, and all 8 of the data points for RF mice showing complete failure on Pi, it's a very black-and-white test bench for USB functionality.  I happen to have a hot-running LAN9512, so I may be able to provide relevant testing if the 1.8v issues are thought to couple to USB operation.

                                   

                                  Morgaine.

                                  • 74. Re: RG1 1.8v regulator
                                    PeteL

                                    J

                                     

                                     

                                    Connecting the two 1V8’s is a sub optimal piece of design (you can look that up in the engineering translation dictionary - starts with a 'c' ends in ‘up’), and I didn't think that was of debate.

                                     

                                     

                                    The design did go through extensive review within the 'inner circle' of supporters who 'know' and have worked with the chips before especially the BCM. Both prototypes and pre-prototypes had this same connection and that of course made it more difficult. I also suspect, had there not been some reason to go and look, it would have never been identified. Just for the record, your technical input is appreciated, but rather than just implying - you could have just asked? Maybe you did earlier and I missed it.

                                     

                                     

                                    We tried to do the best job possible with the limited support and resources that the early phase project had. (We were going to make 5000-10,000 beta boards max). None of the early stress testing revealed the issue and only a small population (sub 0.01%) are reported to run unbearably hot (although more may, just not flagged up because it does not concern their owner - they are just having fun with it). Of the returns I have for analysis, I have still have not found a real ‘steamer’. These could be in part due to poor underfill or even a short/defect elsewhere on top of what we are asking the chip to do.

                                     

                                    There is an implication in posts that this is responsible for something else to do with USB but to date no info is forthcoming? (Stop press - just seen that other thread - will go and look later).

                                     

                                    It doesn't matter if you spend £1 or $10M things slip through, and there have been some very high profile events in that $10M category in all walks of engineering!

                                     

                                     

                                    I remember saying at the outset that Pi would never be perfect - just doesn't happen in engineering there is always something to be optimised, improved. What we do need to do is measure, evaluate, garner input and decide what, if anything, needs to be done. And I do appreciate the work done by people on this thread already.

                                     

                                     

                                    Pete

                                     

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