Pow­er Con­trol — Know and con­trol the state of both ac line volt­age and dc pow­er

sup­plies. Phys­i­cal­ly dis­con­nect line cords and oth­er pow­er cables when you are not work­ing on live equip­ment. Use a lock­out on cir­cuit break­ers. Dou­ble-check visu­al­ly and with a meter to be absolute­ly sure pow­er has been removed.

Inter­locks — Unless specif­i­cal­ly instruct­ed by the manufacturer’s pro­ce­dures to do so, nev­er bypass an inter­lock. This is rarely required except in trou­bleshoot­ing and should only be done when absolute­ly nec­es­sary. Inter­locks are there to pro­tect you.

The One-Hand Rule — Keep one hand in your pock­et while mak­ing any mea­sure­ments on live equip­ment. The hand in your pock­et removes a path for cur­rent to flow through you. It’s also a good idea to wear shoes with insu­lat­ing soles and work on dry sur­faces. Cur­rent can be lethal even at lev­els of a few mA don’t tempt the laws of physics.

Patience — Repair­ing an ampli­fi­er isn’t a race. Take your time. Don’t work on equip­ment when you’re tired or frus­trat­ed. Wait sev­er­al min­utes after turn­ing the ampli­fi­er off to open the cab­i­net — capac­i­tors can take sev­er­al min­utes to dis­charge through their bleed­er resis­tors.

A Ground­ing Stick — Make the sim­ple safe­ty acces­so­ry and use it when­ev­er you work on equip­ment in which haz­ardous volt­ages have been present. The ground wire should be heavy duty (#12 AWG or larg­er) due to the high peak cur­rents (hun­dreds of amperes) present when dis­charg­ing a capac­i­tor or trip­ping a cir­cuit break­er. When equip­ment is opened, touch the tip of the stick to every exposed com­po­nent and con­nec­tion that you might come in con­tact with. Assume noth­ing acci­den­tal shorts and com­po­nent fail­ures can put volt­age in places it shouldn’t be.

The Bud­dy Sys­tem and CPR — Use the bud­dy sys­tem when work­ing around anye­quip­ment that has the poten­tial for caus­ing seri­ous injury. The bud­dy needn’t be aham, just any­one who will be near­by in case of trou­ble. Your bud­dy should know how to remove pow­er and admin­is­ter basic first aid or CPR.

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