Slashdot Mirror


Raspberry Pi Production Delayed By Factory's Assembly Flub

nk497 writes "The first shipment of Raspberry Pi devices has been delayed, after the factory manufacturing the cheap educational computer used non-magnetic jacks instead of ones with integrated magnetics. The problem is already nearly fixed, but new jacks need to be sourced for subsequent shipments, so those could be delayed slightly. 'It's inevitable, isn't it — you're freewheeling along perfectly happily and then you get a puncture,' said spokeswoman Liz Upton, apologizing for the delay."

27 of 132 comments (clear)

  1. Why the magnetics? by tecker · · Score: 4, Interesting

    Can someone explain to me what advantage a magnetic 8P/8C connector has over a non magnetic one? I have no idea where this would be used. My cables have that little lock tab not a magnet. Does it not need the little tab anymore (that always breaks off)?

    --
    Procrastinating life a way at a rapid rate of speed.
    1. Re:Why the magnetics? by prefect42 · · Score: 4, Informative

      I had the exact same thought and googled magnetic jacks:

      Molex Magnetic Modular Jacks incorporate wire-wound components (magnetics) in standard RJ45 jacks. These integrated magnetics, resistors and/or capacitors filter common-mode noise to provide signal integrity, protect PHY chips, provide DC isolation and offer low-mode conversion.

      I'm assuming that's the case here, and the magnets are providing filtering (given the cable's got a predominantly plastic and copper end it's not going to do much to hold it in place).

      --

      jh

    2. Re:Why the magnetics? by Muad'Dave · · Score: 5, Informative

      As I stated in the other, non-annointed article and posted here, the magnetics are actually tiny transformers used to convert from differential to single-ended signals and to isolate. Additionally center taps can be used for PoE.

      "The magnetics in question aren't to hold the connector in like those in a Mac power cord, but rather the tiny transformers that are required for Ethernet differential signal isolation/transformation."

      --
      Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
    3. Re:Why the magnetics? by Anonymous Coward · · Score: 5, Informative

      I'm assuming that's the case here, and the magnets are providing filtering (given the cable's got a predominantly plastic and copper end it's not going to do much to hold it in place).

      They're not magnets. They're tiny transformers and inductors that magnetically couple the signals while providing 1.5 kV DC isolation and some filtering against common-mode disturbances.

    4. Re:Why the magnetics? by Dave+Whiteside · · Score: 3, Informative
      --
      who where what when now?
    5. Re:Why the magnetics? by fuzzyfuzzyfungus · · Score: 2

      Still reasonably common. I don't have exact figures or anything; but you'll still quite often see those distinctively chunky, rectangular passives placed in neat rows just slightly behind the ethernet jacks on devices where space constraints aren't a huge issue. They essentially double the board footprint of the jack, so I assume that they've been stamped out in laptops, classier switches where density counts, and the like; but cheapie switches, home router boxes, NICs of indifferent quality, and so forth are still using them. Sometimes even pin-through-hole DIPs, no less, not even surface mount...

      They do tend to have all the magnetics for at least one port, often two or four, crammed into one package, I don't think I've ever encountered discrete ones on anything remotely recent; but magnetics separate from jacks are still around.

    6. Re:Why the magnetics? by ifrag · · Score: 2

      For those cables, I think that would be a Ferrite Bead.

      --
      Fear is the mind killer.
    7. Re:Why the magnetics? by TheGratefulNet · · Score: 2

      isolation transfomers.

      had they said that, yeah, you want that in ethernet. products that omit that (popcorn hour, cough cough) have ruined NICs and bad performance for noise.

      in audio (spdif) you also want pulse transformers. same idea.

      --

      --
      "It is now safe to switch off your computer."
  2. Magnetics by Anonymous Coward · · Score: 5, Informative

    From the Raspi forums :

    "It doesn’t mean no network connection at all on all devices, but this board has been designed for a magnetic jack. The magnetic bits mean better signal integrity, better filtering and shorter transmission distances for data."

    "Magnetics refers to the presence of transformers and chokes which are used to isolate the Ethernet wires from the RaspPi’s power supply. and each other and probably to reduce high-frequency noise. Without them you would effectively tie the RX and TX signals together and probably turn the entire network into an aerial for Radio 2 reception."

    1. Re:Magnetics by Muad'Dave · · Score: 4, Informative

      Without the intervening transformer, the TX- and RX- lines would be tied together at ground on the device. In the diagram below, the differential RX+/- and TX+/- signals are turned into single-ended RX and TX by the transformers. Removing the transformers connects RX- and TX- to ground, which is a Bad Thing(tm).

      RX+_____3 E_______RX
                    3 E
                    3 E
      RX-_____3 E_____GND

      TX+_____3 E_______TX
                    3 E
                    3 E
      TX-_____3 E_____GND

      --
      Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
    2. Re:Magnetics by Anonymous Coward · · Score: 3, Informative

      Radio 2: UK radio station broadcasting crap music for housewives.

    3. Re:Magnetics by petermgreen · · Score: 2

      They also crucially provide center taps to provide a path for DC currents from the transmitter to ground and to give the receive signal the correct common mode level. Also because of the aforementioned center taps the pinouts of a jack with integrated magnetics will almost certainly differer from a plain jack.

      http://www.smsc.com/media/Downloads_Public/lan9000/9512_sch.pdf

      (that is a reference design for the lan chip the Pi guys are using)

      So without the correct magnetics things are unlikely to work at all.

      --
      note: i'm known as plugwash most places but i screwd up registering that here somehow in the past and now can't register
  3. Before anyone makes any silly comments... by Muad'Dave · · Score: 4, Informative

    The magnetics in question aren't to hold the connector in like those in a Mac power cord, but rather the tiny transformers that are required for Ethernet differential signal isolation/transformation.

    --
    Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
    1. Re:Before anyone makes any silly comments... by eclectro · · Score: 2

      It would have been more informative to call the internal circuitry "filters" rather than "magnetics," which is conceptually more accurate.

      That said, this has to be great advertising for Molex.

      --
      Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
    2. Re:Before anyone makes any silly comments... by Muad'Dave · · Score: 2

      They're not just filters, they're transformers that (as a result of their inductance and capacitance characteristics) also act as filters. I chose molex simply because they were first on the search and seemed informative.

      They've been called 'magnetics' in this context for quite a while - I guess it's a bit of an industry standard. They also have cute terms like PHY and MAC.

      --
      Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
  4. Re:How wrong I was! by Anrego · · Score: 3, Insightful

    I can understand this critisism as I've had it many times over many different periods of "omg, not another <whatever> story".

    But I'm way too damned excited over the Rasperry Pi to care! Kinda fun being on the other side of things for a change :D

  5. Fucking magnets. by Chrutil · · Score: 5, Funny

    How do they work?

  6. Re:Seems reasonable enough by ledow · · Score: 4, Interesting

    Someone in China (the same guys that did the mistake in the first place, which most mentions have assumed to be a deliberate cost-saving measure rather than a true accident) has to receive those units back, hand-unsolder 10,000 connectors and hand-solder 10,000 correct connectors back into place before then packaging them up and sending them back to the UK.

    Where, still, as far as we know, there's been no tests of functionality other than networking (i.e. they haven't seen if similar issues affect the other ports like the display, etc.). And then someone has to test a good portion of them again before sending them onto the suppliers.

    Meanwhile, they have to source a supply of 100,000's of the proper connectors for future runs, which they are just starting now. And hope that the network WAS the only problem.

    In effect, they did no actual testing of the actual device functionality ("it'll all just work if the factory did their job") until the entire first batch was opened in the UK. The testing in the manufacturing facility was purely electronic and COMPLETELY missed this problem (surprise, surprise). And immediately upon opening them here, they spotted a problem, which took FOUR DAYS to isolate (and was isolated only because they were baffled and broke one of the connectors open and happened to spot the difference) and now it all has to be sent back for more work.

    That's a mite more than a "minor bump". Not irreconcilable, but certainly not a bump. More like a hard jolt with metal grinding. I sincerely hope it doesn't turn into another OP, but given that we've gone from "No preorders" to well, pre-orders, and a full launch to, well, we'll tell you when we have a working device in the same country as our distributors, the slippery slope has certainly started. Of course they can recover the situation. The question is, what other mistakes have they made in their supply chain of making 10,000 bare PCB's with components (something that happens thousand-fold times every day).

  7. Bye Bye Raspberry Pi by Oswald+McWeany · · Score: 4, Funny

    Bye Bye, my Raspberry Pi,
    I thought that I might buy you,
    but the warehouse was dry,
    those good old boys say just wait one more month,
    but you keep running into delays,
    yeah, you keep running into delays.

    --
    "That's the way to do it" - Punch
  8. Re:So, delayed anyway. 20-30% increase in cost... by ZeroSumHappiness · · Score: 2

    Blame the extortionate tariff on importing components versus the lack of tariff on finished goods for production being outsourced. Here's a direct petition on the matter: http://epetitions.direct.gov.uk/petitions/27158 -- that is the direct reason manufacture is being outsourced. From what I understand of the Foundation's statements on the matter no economy of scale could overcome the cost of the tariff because the bill of materials cost would be too high to be profitable at the desired price point as a result.

    And I don't see any cost increase. Model As are $25 before tax and shipping. Model Bs are $35 before tax and shipping. That has never changed.

  9. Re:So much for opensource hardware taking off... by Ritz_Just_Ritz · · Score: 3, Informative

    Actually, no. This is what happens when you outsource manufacturing to vendors in countries like China where it is common practice for them to quietly substitute parts between the reference design stage and when the device hits production. Sometimes, you get lucky and they even tell you in advance that they're doing this and you have a chance to evaluate impact on the design. Most times, they simply do it and pocket the difference in cost while hoping not to get caught.

  10. How's that cheap Chinese production looking now? by Rogerborg · · Score: 3, Insightful

    Still good value?

    What about when the returns start flooding in because a 1 cent component failed when a 2 cent one might have soldiered on? Budgeted for handling that?

    I know these guys are amateurs, but do they really need to keep demonstrating it?

    --
    If you were blocking sigs, you wouldn't have to read this.
  11. Re:So, delayed anyway. 20-30% increase in cost... by Anonymous Coward · · Score: 2, Insightful

    Perhaps you would be interested to find out what the tariff actually is? Or perhaps your definition of "extortionate" isn't the same as mine. Hint: the upper limit across the various electronics tariffs, last I checked, was 14%. Broadcom does not deserve the blind trust geeks seem to be awarding it over this Raspberry Pi project: even though some of the characters may be familiar, we're a long way from the days of the BBC B where a bunch of bright uni students got together with academic entrepreneurs.

    It is, of course, quite absurd to charge on components but not on finished computers. A tariff should be a function of rights imbalance and amount of work involved. So a relatively free nation would not be subject to significant tariff, whereas a nation like China would be subject to a high tariff, the tariff increasing for completed products as more work was done under conditions not acceptable to the consumer nation. I cannot think of a better way to get developing countries to improve their citizens' fortunes. Can you?

  12. Re:Seems reasonable enough by Dave+Whiteside · · Score: 4, Informative

    Quotesdfrom the forum
    ''Jamesh is right – they sent us test units which *did* have the right part on before they moved to a larger batch. "

    --
    who where what when now?
  13. Re:How's that cheap Chinese production looking now by ColdWetDog · · Score: 2

    This sort of thing is precisely why the standard Slashdot rant of "all they did was put x, y and z together, this isn't innovating!" is so much silliness. It's not easy to mass produce things. It takes planning and more planning. It takes money and more money than you planned on because some small aspect of Murphy's law is going to pop up and rip your balls off.

    It's why the Motorola Xooms of the world come with stupid little missing bits and even why our fearless denizen of perfection, Apple, still screws first releases up 99 times out of a 100.

    Production electronics is not building a Heathkit in your bedroom.

    --
    Faster! Faster! Faster would be better!
  14. Re:Seems reasonable enough by Anonymous Coward · · Score: 2, Informative

    I hate to stereotype, but this is quite typical for China. You need to watch them closely or they will cut corners whenever possible.

  15. Inductors? by Dan+East · · Score: 2

    I have only dabbled in electronics, but I don't care for the term "magnetics" (nor I have ever heard it before). I would think "inductor" would be a better term. Anyone who actually knows what they're talking about care to illuminate what the difference is between "magnetics" and inductors?

    --
    Better known as 318230.