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Repairing Lightning damage

Discussion in 'Electronic Repair' started by Puckdropper, Jun 29, 2007.

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  1. Puckdropper

    Puckdropper Guest

    I have a Zonet ZSR1104WE Wireless Broadband Router. It's about 3 years
    old, and until last night worked just fine. After a storm last night,
    the router quit working. It shows no signs of life.

    I've tested the AC adapter with a meter, and it's showing 16V (no load.)
    So, I opened the case up and started tracing the circuit. One diode (D1,
    IN5.... (can't see the numbers)) near the power input has shorted (tests
    open both ways), but my question is where to go next? I've looked
    unsuccessfully for a fuse of some sort, the next components in the
    circuit are a B1412 transistor (Q5) and a choke (L1.)

    From the B1412, the circuit continues to RT34063a (u9) and then to a
    series of resistors (R9-R5).

    Any help would be appreciated.

    Puckdropper
     
  2. Eeyore

    Eeyore Guest

    Is it open or short ? It can't be both.

    Replace that first and go drom there.

    Graham
     
  3. Wolfi

    Wolfi Guest

    Am 29.06.07 01.22 schrieb Eeyore:
    The diode has shorted, hence opened the path both ways ;-)
     
  4. Puckdropper

    Puckdropper Guest

    Yeah... Something like that.

    I should have said: The meter reads 0 both ways, just like a wire.

    Puckdropper
     
  5. Puckdropper

    Puckdropper Guest

    $:

    *snip*
    Ok, I've got another question: I've got only 1N400x series diodes in my
    parts collection. Is it worth the trouble substituting one for the
    1N500x series diode in the circuit? The AC adapter is rated at 12V
    1000mA.

    If it works, I'll definately order the proper replacement, I just hate to
    blow components when I don't have to.

    Puckdropper
     
  6. What? Is this some sort of zen linguistic challenge?

    Leonard
     
  7. Meat Plow

    Meat Plow Guest

    A 1 amp diode should be ok for a test but I think you've got problems
    further down the line from my experience with lightning damage warranty
    repairs. I hope you don't though :)
     
  8. If it works, use it and don't worry about the diode. :)

    12 V at 1 A can't hurt a 1N400X.

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
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    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
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  9. Puckdropper

    Puckdropper Guest

    The diode was a 1N5817, a schottkey. Out of the circuit, though, it
    tested fine. Guess that means there's problems somewhere else.

    I tried putting it back in, but ran in to problems with one of the holes
    filling with solder.

    My guess is there's problems on down the line, and they're network side
    related. All three network devices I had (2 routers and a switch) are
    acting funny.

    Puckdropper
     
  10. Meat Plow

    Meat Plow Guest

    Yeh I've replaced loads of switches and other net appliances after
    lightning strikes when I worked for a networking company several years ago.
    Those things just don't tolerate it well.
     
  11. w9gb

    w9gb Guest

    Need a little more experience in sodlering -- don't you? Good techniques
    can be demonstrated in 5 minutes or less to a 'newbee' or garage tree home
    repairer -- and I have seen these devices ruined due to frustration, lack of
    patience and anger management issues.

    Get some good solder wick and a sewing needle.
    You may not have taken a direct hit -- it may have been an "induced" power
    surge.

    You may also have damage through your Ethernet (10/100) ports.

    I have seen an induced surge (from lightning striking within 500 feet of
    location) vaporize copper traces right off serial (RS-232) cards from
    external modems. That strike had no effect on AC, but rather came through
    phone lines -- right through external modem (back to Hayes) and to serial
    card (grounding through computer ground)

    Jumpered the missing traces -- and everything worked (in my case).

    gb
     
  12. Puckdropper

    Puckdropper Guest

    I was getting frustrated earlier, so I quit. I'll try it again later
    today, and hopefully get that hole cleared out without damaging the
    board.
    Everything you said sounds like it's what happened. There's NO physical
    evidence of damage on the boards, all three devices are acting strangely.
    (Well, except the dead router.)

    I've got a replacement router and switch on the way, I just wanted to try
    to repair the ones I have for the experience.

    Puckdropper
     
  13. w_tom

    w_tom Guest

    It is routine for a direct strike to leave no visible damage. Also
    routine is for many to assume a surge entered on phone line when
    unknown is a protector installed on all telephone subscriber lines
    (for free).

    Best evidence is the dead body. Damage is how a human learns where
    effective protection was missing; where a surge was permitted to enter
    the building.

    How large was the surge? Routers already have effective internal
    protection. The surge had to be so large as to overwhelm that
    internal protection. The surge found earth ground, destructively, via
    that router. That is a direct strike.

    Long after surge electricity was flowing through everything in a
    path from cloud to ground, only then something in that path failed.
    What died inside that router? What was the path through that router?
    A destrutive electical circuit formed by overwhelming internal
    protection because a direct strike was not earthed before entering the
    building. Learn from that damage so that future damage need not
    occur. It is routine to have direct lightning strikes and no damage;
    when an effective solution is installed. Use information from the
    'dead body' - the electrical path in and out of the router - to find
    and eliminate the problem. Where did a surge enter the building?
    That is where a solution is installed.
     
  14. TMI

    TMI Guest

    Dear PD,

    The transient that BBQ'ed the router, could have scrambled the
    settings down stream. Follow the manufacturers instructions to reset
    defaults.

    It hardly seems worth your trouble but I know the Holy Grail Syndrome
    all too well. No doubt, there are caps to ground, electrolytic,
    tantalum, film or ceramic, that are placed both before and after the
    diode. This should be the source of your short if the diode is in fact
    OK. You need to use the 200 ohm setting on a good meter to narrow
    things down. Touch the probes to each other to set or at least see
    zero ohms then probe each component directly, looking for the least
    resistance, then unsolder to verify.

    Get yourself some solder-wick, rosin soldering paste and some quality
    solder (Sn 63 multicore tin/lead if you have a choice). Clean your
    iron's tip with scotchbright until you break through any dark oxide.
    Sometimes scraping lightly with a single edged blade is better. This
    is lead so, no food, wash hands etc. Do not scrape through the
    plating.

    Heat the iron and dip it in the rosin as it's getting warm. Hold a
    piece of solder against it. As soon as it begins to melt, quickly coat
    the entire tip. Wipe the hot tip to remove excess solder and rosin,
    then apply a bit more solder. This is how the tip must look before it
    is put away and just before you use it, Bright, shiny and fully coated
    with a slightly noticeable bit of extra solder near the very tip.

    The solder must be wiped and renewed just before each operation.

    Touch the iron to the hole in question and add a bit of solder.

    Remove the heat when it begins to flow.

    Place the solder wick on top of the hole and press the iron on top of
    the wick. The solder should be drawn into the wick.

    A solder sucker could also be used but fresh solder wick is a better
    bet for a beginner.

    Tom
     
  15. Eeyore

    Eeyore Guest

    That's a SHORT.

    An OPEN is when the meter reads 'infinity'.

    Graham
     
  16. Chris Jones

    Chris Jones Guest

    The terms "short" and "open" mean specific things in the field of
    electronics and people will misunderstand you if you use them
    interchangeably for anything that isn't working. "shorted" means that
    something does conduct electricity, "open" means that it does not conduct
    electricity.

    Chris
     
  17. HapticZ

    HapticZ Guest

    i concur, impulse emf from millions of amperes flowing nearby does indeed do
    some remarkable things!

    almost as if by majic, i had a coiled extension cord on a bare plank porch,
    it was clear of anything and completely unconnected to anything. after a
    strike about 30 feet way, it was melted and fused together, no copper showed
    any hint of black conduction damage, only the nice clean smell of lotsa
    heat!

    better u spend time finding a replacement router than hours trying to fix
    this!
     
  18. Puckdropper

    Puckdropper Guest

    *snip lighning story*
    You're probably right... However, some of this is a bit of a learning
    experience. I never realized there were 1N5x series diodes, let alone a
    1N5817 being a schottkey.

    I've got a replacement router ordered, it should be here in a couple
    days.

    Puckdropper
     
  19. Puckdropper

    Puckdropper Guest

    I shall endevour to be more careful with the terms in the future. Thanks
    for not getting too confused. ;-)

    Puckdropper
     
  20. Puckdropper

    Puckdropper Guest

    I tried that first. I think it's press and hold reset for 20 seconds,
    but it could be longer. I'm hoping the memory isn't fried.
    There's about 5 of them near the power input. I'll give them a look and
    see what they're doing.
    I don't have the rosin soldering paste, but I do have ZnCl flux. Is this
    the same kind of thing, or do I need to go looking for the rosin
    soldering paste?
    I'll give your suggestions a try. I'm wondering if there's a lead free
    solder used on the board, due to the trouble I had desoldering the diode.
    (I had done other desolderings from other boards and this one was much
    more difficult...)

    Puckdropper
     
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