Safety Tips For Working On Amps

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by stratman_el84, Oct 6, 2008.

  1. stratman_el84

    stratman_el84 Member

    Mar 16, 2008
    Kalamazoo MI area.
    I posted this as part of a reply in another thread. I thought it deserved it's own thread & post, as these amps we tinker with can easily seriously injure or kill you if you don't pay sufficient attention to safe work habits regarding electrical equipment containing lethal voltages and current.


    Here are some tips to working safely with amps:

    When working in a live chassis, especially if inexperienced, the most important thing is to not work alone. Make sure someone is there to kill power/knock you away if needed. Set a wooden-handled broom close, and instruct the other person to use that to push/knock you away if needed, and to NOT grab you bare-handed, as they'll get shocked too. Make sure there's a power-kill switch that kills power to the whole bench if possible, close and handy.

    Make sure the amp is well-supported and won't fall over. Keep the area clear of anything that might get in the way of your arms and body, or fall/get knocked into the chassis around where you're working. Clear away any wires/cables on the floor around where you'll stand/work.

    Plan each step of what you'll be doing and how you'll do it before starting. If possible, use clip-leads to attach meter leads to test points before applying power. Always keep one hand behind your back or in your back pocket so as not to provide a ground path through your chest and heart.

    Wear safety glasses. I know many will pooh-pooh this, but all it takes to realize the value of this is one time of having a cap explode or a violent short to happen when you've got your face down there.

    Triple-check your meter settings for correct measurement type and range before applying power, and also check meter leads are properly and tightly seated.

    If planning on working on the amp powered-down (replacing parts, attaching meter leads, etc), you can make a simple discharging tool of two lengths of wire, a 100K 1 watt resistor and two insulated alligator clips (available at Radio Shack). Solder a wire to each end of the 100K resistor, then an insulated alligator clip to the remaining ends. Put a piece of heat-shrink tubing over the resistor and its' leads (remember to slide the heat-shrink tubing on *before* you attach the second insulated alligator clip!).

    Attach one clip to the chassis FIRST! Clip the other end to the metal shaft of an insulated-handle screwdriver or you can use a piece of wood with a nail in the end, and attach the clip to the nail. Touch the screwdriver/nail tip against the hot side of each filter cap for about 30 seconds, starting at the lowest-voltage point in the series of caps and working towards the cap closest to the rectifier diodes or tube. Then attach the clip to the hot lead of the filter cap closest to the rectifier diodes/tube and leave it there while you work, for safety. DON'T FORGET TO REMOVE IT WHEN DONE!

    Here are some additional general rules to follow whenever working on or around any equipment containing dangerous voltages and current:

    NEVER work tired, frustrated, sick, hungry, impaired, distracted, or upset. Wait for another better time.

    NEVER rush or hurry! Always think two or more moves ahead. Be situationally-aware.

    Keep distractions to a minimum, and don't try to carry on a conversation/talk on the phone. Don't have a crowd around.

    Wear shirt-sleeves to avoid cuffs snagging. Remove necklaces/rings/watches/bracelets, etc.

    Keep tools out of the way, but handy. Don't stretch to reach things.

    Most importantly, try to relax. Be methodical. Make and follow a checklist if this is new to you. Don't fear electricity, but DO respect it.

    I've worked on equipment that contains extremely lethal voltages/current for most of my life and haven't been hurt because I developed safe work habits as described above, just as one must develop safe driving habits. Always think things through before you do them. Safety around electricity is a mindset, not a magic list.


  2. TweeDLX

    TweeDLX Member

    Mar 24, 2008
    Port Angeles, Washington
    This should be one of those "sticky" threads at the top of this forum. I've seen various questions about this many times. Great post![​IMG]

  3. JPF

    JPF Member

    Jan 4, 2002
    New England
    +1. Great post, Strat - thanks.
  4. Wheels

    Wheels Gold Supporting Member

    Apr 5, 2004
    Thanks for the detailed posting, Strat.

    Another reason why I should just play the damn things, not work on them!

  5. DucRyder

    DucRyder Member

    Nov 22, 2005
    not Detroit
    I have a 10K 1 Watt and a 100K 1/2 watt resistor. Can I use one of these? Radio shack didn't have the 100K 1 Watt...
  6. jawjatek

    jawjatek Member

    May 30, 2007
    Cumming, GA
    I would highly recommend actually studying and learning some electronics theory, if not getting at least a 2-yr tech degree. Ignorance can be dangerous. Based on what I've read here, a lot of folks seem to have skipped this part. :NUTS

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