What is a safe way to test a non-working 'torchiere lamp'?

Discussion in 'General Electronics Chat' started by steveray, Jul 14, 2008.

  1. steveray

    Thread Starter New Member

    Jul 14, 2008
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    I have a non-working torchiere lamp. As far as I know the halogen bulb is okay, so I assume there is a fault either with the bulb connectors (contacts) or the switch.
    *** What is a safe way to test the circuit at both sites (i.e., at the bulb connections and at the switch)? ***
    I have a simple 'continuity tester.' Is it safe to use that (to check the bulb connectors) with the lamp 'on'?

    I'm a novice with electricity and mainly want to make sure I don't electrocute myself.

    (Actually, I guess if I can safely test the bulb connectors and those seem okay, I can just conclude from that that the fault is in the switch. But I assume that to do that, the power has to be on?)

    Thanks. Replies appreciated.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Do not use a continuity tester with the lamp plugged in, as the continuity tester will have it's magic smoke let out, possibly with a loud "BANG!" and a bright flash. :eek:

    Unplug the lamp from the wall, and remove the lamp. Check for continuity through the lamp, and from each prong of the plug to the lamp socket/bulb connectors.

    I've found that the inexpensive torcherie lamps one usually finds at discount stores go bad at the switch. The contacts get burned, and they stop working.

    Warning: Finger oils on the bulb can cause it to shatter when it gets hot. Handle the bulb with a clean, dry cloth or paper towel. You can clean the bulb with isopropyl alcohol.
     
  3. steveray

    Thread Starter New Member

    Jul 14, 2008
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    Thanks. By "remove the lamp" did you mean remove the "bulb"?

    Also, what exactly does "check for continuity through the lamp" mean? (I really am a novice, sorry.)

    Does "from each prong of the plug to the lamp socket/bulb connectors" mean that I should connect one probe of the continuity tester to each plug prong and the other probe to each bulb connector? If so, should the tester light up only with one connection for each probe if it's working properly?

    Thanks again.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Yes.

    Put one probe on one bulb terminal, and the other probe on the other terminal. You should show continuity. If not, the bulb is burned out.

    Yes.

    Start with one of the probes on one of the bulb socket's connectors. Try one prong of the plug. if no continuity, try the other prong of the plug. If you don't get continuity either side, then the lamp cord, the switch, or the plug itself is defective.
     
  5. steveray

    Thread Starter New Member

    Jul 14, 2008
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    You wrote "If not . . . [etc.]" but don't you mean that the bulb is (probably) burnt out if they do show continuity (assuming the problem isn't with the lamp switch rather than with the bulb or with the bulb terminals)?

    BTW, don't the lamp's bulb terminals themselves sometimes 'go bad' -- I mean even just from collecting grime over a long period of time, resulting in their not making good contact with the bulb's contacts?

    Thanks again.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    Incandescent bulbs have continuity through them. The filament is generally made of tungsten. It has a low resistance when cold. As it reaches operating temperature, it's resistance increases.

    If there is no continuity between the bulb's terminals, then the filament is burned out. There really isn't a good way to repair them.

    That's where the isopropyl alcohol comes in. If the contacts are not bright and shiny, you can use a clean pencil eraser to scrub off any corrosion, then clean off the residue with isopropyl. Allow the bulb to dry completely before applying power.

    Note that isopropyl alcohol burns with a flame that is almost invisible. It's not that hazardous per se, but it is flammable. Use appropriate precautions.
     
  7. steveray

    Thread Starter New Member

    Jul 14, 2008
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    I think you were referring to the bulb's contacts while I was referring to the lamp's. The bulb should be okay because at one point I checked it in another lamp and it worked. However, I thought the contacts in the lamp itself (i.e., those that the bulb's terminals fit into when the bulb is inserted) might not be making proper contact with the bulb's.

    What I want to do is rule out the possibility that there is a problem with the lamp's contacts (i.e., with the bulb terminals), in which case I think I can assume the problem is instead with the lamp's switch.

    Again, I think you're referring to the bulb's contacts, rather than the lamp's. But presumably the cleaning method would be the same.

    Thanks again.
     
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