blowing electronics

Discussion in 'The Projects Forum' started by GARYN, Jun 28, 2010.

  1. GARYN

    Thread Starter Member

    Sep 4, 2009
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    I have had many differant contradicting precautions that need to be taken when welding on machines containing electronic components and PLCs. These have come from welders, fitters and electricians but i would like to know from you electronic experts what are the dangers and why and how to weld in the knolwedge that you will not destroy anything.

    I have heard the following -

    remove PLC from panel
    just switch PLC off
    put earth clamp near to point off weld and dont do anything
    etc etc

    If you do put the earth return clamp near the weld and give it a good contact why would it try to travel through a PLC further away, is this because some componets have the 0v grounded, and when some people say disconnect a PLC, is the mains power and earth enougth or every input and output? If someone could give me some info on the this it would be greatly appreciated- i could not find much on the net.
     
  2. PackratKing

    Well-Known Member

    Jul 13, 2008
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    215
    The safest way whenever possible, is to disconnect and remove all printcircuit's from the object being welded upon.

    I'll defer to Sgt. Wookie here, and ask how much effect an arcs corona might have on the likes of cmos chips, which I have often wondered about anyway. :rolleyes:
     
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  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    You also have to consider the type of welding being done. I can image that a TIG welder with HF for starting might pose a different problem than a DC stick welder.

    John
     
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  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Arc welding is safe for electronics as I have seen this done in the gulfcraft lauch factory here.
    The current will flow to earth rod.

    But I donno about CMOS. and uPC's
     
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  5. GARYN

    Thread Starter Member

    Sep 4, 2009
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    Thanks for the answers but is the problems caused by current flowing directly through the components or inductive pick up when the arc collapses.
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    I think it's ESD
     
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  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    The problems, if any, are probably unpredictable. My comment about TIG was based on the fact that when one returns an argon tank in the USA, the dealer always checks the tank for signs of an arc over -- a little spot where an arc momentarily jumped to the tank. I am not exactly sure how that happens. It was explained to me that the HF can somehow find a way to do that. My guess is that a poor or broken ground on the piece being welded could do that. I surmised that a piece of electronic equip might be subject to similar HF effects if it were near the welding and had a good ground. When I have returned argon-CO2 tanks used for MIG, they were not checked.

    In my personal experience, however, I have used TIG to repair engine mounts and exhaust headers on small aircraft without removing the radios and there was never a problem. Also, there must be welding being done on board large ships without removing all the electronic gear. In both situations, the welding ground is considerably closer to the workpiece than any electronic equipment is.

    Since I have never actually experienced a problem and was only surmising that it might occur in a TIG situation, I can't say whether that is at the beginning or end. HF is usually used for starting the arc.

    John
     
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  8. Bosparra

    Member

    Feb 17, 2010
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    Interesting question, especially considering welding on a motor vehicle where allot of electronics are grounded through the chassis. You can disconnect the battery, but there are too many other grounding points to disconnect everything.
     
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  9. BMorse

    Senior Member

    Sep 26, 2009
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    I have welded with mig welders on electronic enclosures with the circuits still in them, and have not had any problems with it. Just as long as the welder ground is placed as close to where you are welding... and the earth ground (mains power also) is disconnected...... but don't take my word for it, what worked for me may not work for you... but I have destroyed a couple of cell phones while welding and / or using the plasma cutter (by just having the phones on my person while welding), apparently just being too close to the equipment really messes up the cell phone circuits.....

    My .02

    B. Morse
     
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