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So what's the truth about lead-free solder ?

Discussion in 'Electronic Repair' started by Eeyore, Jul 24, 2007.

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  1. PeteS

    PeteS Guest

    Another major issue is tin whiskers. We have hard evidence at
    $WeBuildAvionics (where I am currently consluting) that the current Pb
    Free / RoHS solder mixes have significant problems with growing
    whiskers, leading to wonderful issues such as short circuits developing
    under BGAs a few months after production. In a Flight control computer
    (don't laugh - in a fly by wire environment it's the ONLY flight control
    and virtually all late model airliners use it) this is Not a Good Thing
    [tm].

    The whole RoHS / Pb free thing is a political issue - the processes for
    Pb Free use more hazardous substances than they get rid of.

    Typical EU beauraucrats - unelected, overpaid and have to find something
    to regulate to justify their existence. [1]

    Cheers

    PeteS

    [1] Their existence, even from birth, might not be justifiable.
     
  2. Arfa Daily

    Arfa Daily Guest

    Aha ! So you are comparing wide bandwidth high bit rate satellite
    transmissions, displayed on your high res PC screen, with an analogue PAL
    signal. That is not quite the same as a low bit rate highly compressed
    digital terrestrial transmission, displayed on an ordinary household TV set.
    I do not have an issue with a setup such as yours producing comparable - or
    even possibly superior in some instances - subjectively viewed pictures. But
    that was not the comparison that I was making, when I voiced the opinion
    that the digital pictures ( now being foisted on the public via the
    terrestrial TV transmission network ) did not compare to the analogue PAL
    pictures that we have been used to.

    Arfa
     
  3. Arfa Daily

    Arfa Daily Guest


    It's good to hear at last from someone involved in the avionics industry,
    and it's also good to hear that this particular industry is identifying
    serious problems with the technology, as that might at least help to
    maintain their exemption for some years to come. I really hope that the
    industry has sufficient strength to stand up to this legislation, and to
    continue to maintain their position of refusing to use it on safety /
    reliability grounds. With my daily dealings with lead-free solder, and all
    of the problems that it has brought to consumer electronics, the thought of
    being held seven miles up in the sky by equipment using the same technology,
    is truly worrying to me.

    I cannot agree more that this whole thing is a poorly thought through
    example of 'bandwagon politics' and job justification.

    I would be interested in hearing any other input that you may have on the
    subject, with regard to the avionics industry. Both anecdotal and factual
    would be welcome, and I am sure that Graham (who started this thread) would
    like see more from you, as well.

    Arfa
     
  4. Eeyore

    Eeyore Guest

    I agree with you.

    The same holds for DAB too.

    Graham
     
  5. clifto

    clifto Guest

    I get regular breakups on cable, on multiple channels, at all times of day;
    picture plus sound, picture only, and sound only. Picture loss includes
    pixelization, cessation of action with partial pixelization, full loss of
    action for seconds at a time. A visit from the cable company can fix that
    for three or four days at a time.

    The video reproduction is very reminiscent of the old 16-bit PC video
    cards, especially in low-light scenes when it starts to look like the
    video has about 16 brightness levels (four-bit video).

    I used to get far better picture quality with rabbit ears from stations
    a hundred miles or more away. I can take the snow when I don't have to
    tolerate all the nasty artifacts in a digital picture.
     

  6. You're an idiot, and have yet again said absolutely nothing.
     

  7. Read it again. He said PROFESSIONAL, and NEWER equipment is inferred.
     
  8. Spot on.

    It is akin to a high end HD digital video card also carrying a composite
    output jack.
     
  9. Eeyore

    Eeyore Guest

    Since when did PROFESSIONALS not use PAL ?

    Don't talk about stuff you have no experience of. It makes you look even more
    retarded than normal. I was the technical manager for an editing equipment hire
    company some years back. I do know what I'm talking about.

    Broadcast TV isn't as wealthy as it once was and don't expect equipment to be
    'upgraded' on a whim.

    PAL (and especially UK PAL) produces a far superior picture to NTSC btw just in case
    you're getting confused.

    Graham
     
  10. US Digital. WalMart. Made by Hisense, model DB-2010. ($200) Broadcast
    only, NOT capable of the cable format. Ready for a single antenna,
    multi-channel subscriber reception planned for the future in some cities.
    It has been out for over two years now, and it looks amazing on an old
    standard set, not to mention on an actual HD set.

    Broadcast digital reception is flawless, and should be the standard...
    Oooops... to late... It is!

    It has component out and composite, and SVHS.

    Two channel audio only.

    Great reception with either a standard set top antenna or a
    preamplified unit, not to mention a rooftop job.

    The "several" remark was just an assumption, but one would think that
    others would include such a feature in their units.
     

  11. SHOCK.... and AWE!
     

  12. Both terrestrial broadcast, as well as satellite uplinks are 6MHz wide
    STANDARD channel slots and transponder slots. That was one of the rules
    of the game back when all this started.

    So, on "terrestrial", one can expect the best picture, as it is "single
    channel per carrier" (SCPC), whereas a satellite uplink from a service
    provider is going to be a "multiple channel per carrier" (MCPC)
    implementation, in 99.9999% of the cases.

    Artifacts are a product of bit error rate. If the bit error rate of
    your reception in zero, you WILL get ALL of the data.

    The other source of artifacts are pre transmission compression.

    In the old MCPC setup, only 6 or 10 channels per carrier could be
    pumped, and it was an MPEG-2 compression schema and a 480i schema.

    Now, they put up to 12 channels per carrier (per transponder) into the
    uplink for 24 or 64 channels per transponder total.

    With HDTV, much more data per frame needs to be dealt with. FEC is
    your friend.
     

  13. Bullshit. That is EXACTLY where the multiple channel per carrier thing
    gets implemented.

    In terrestrial schemes, it is only ONE channel per 6MHz wide carrier.

    Your tuner may say that there are 3 PBS channels on the number 15, but
    the actual frequencies of those channels are all on separate 6MHZ wide
    slots with MAYBE only one which as actually on the channel 15 assigned
    frequency.
     
  14. clifto

    clifto Guest

    Thanks. I'll have to take a look.
    HDTV sucks, at least the little I've seen. The artifacts are too distracting
    for me to watch the picture. When you can get a camera to stand still while
    focused on a still object, so the compression isn't blurring everything,
    there's improvement in sharpness and no snow and, if you're lucky, a
    minimum of aliasing. When you get off the still life and start watching
    conventional programming, the picture goes to hell. I watched a bit of a
    football game while sitting in a furniture store and got a headache from
    seeing the crowd go into and out of focus.
    Wouldn't do me any good. I couldn't get a permit for the fifty-foot tower
    I couldn't afford to put up. Far too many buildings between me and the
    transmitting antennas at Sears Tower.
     
  15. Eeyore

    Eeyore Guest

    'Arfa' is in the UK. There is no 'PBS' here.

    We do have the BBC though, although it's been degraded terribly in the last few
    years on the cross of 'political correctness'.

    Graham
     
  16. clifto

    clifto Guest

    Aw, not so shocking.
     
  17. You must be in a different multiverse location.

    Satellite service gives you 300 plus channels by putting up to 12 6MHz
    wide "channels" into each 6MHz wide slot.

    http://www.tech-faq.com/mcpc.shtml

    http://www.webopedia.com/TERM/M/MCPC.html
     

  18. Damn. You actually made a post that I agree with 100%.

    Seems one must fully encapsulate a finished assembly in transformer
    varnish under vacuum to lock out the whisker growth.

    Serviceability... right out the door.

    Stink factor... worse than it was.

    The whole fucking thing stinks.
     

  19. That is your fault for not calling them and complaining about your
    obviously poor strength feed. That or the dopes actually think they can
    send it out that way from the head end to everyone. That would be really
    sad, and point toward the need for a class action suit. started at a town
    meeting, and including the City Manager.
     

  20. That is referred to as "posterization".

    Remember posters that were of "photos" or "pictures", but could only
    give you a 16 color palette? Distinct lines of separation to "create" a
    gradient.
     
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