How to Change Lamps in Theater Instruments

There are two basic configurations of lamp bases in stage lighting instruments. Pin or prong bases are common in ellipsoidal reflector spotlights, or ERS, and parabolic aluminum reflector, or PAR, lights. Bayonet bases are common in Fresnels. The methods for changing these two lamp base types are slightly different, but in both cases, you must avoid touching the lamp glass with your fingers. The oils from your skin cause the lamp to concentrate heat in one area, shortening the lamp life and sometimes causing the glass to explode. Wrap a rag, the lamp packaging or your clean sleeve around the glass and handle the lamp by the base only.

Pin and Prong Bases (ERS and PAR)

• 1

  Unplug the light for your safety, as you will be handling metal parts.

• 2

  Open the base of the lighting instrument by loosening the nut that holds the base of the instrument in place. On ellipsoidals, you can generally do this by hand, but on older instruments, you may need a screwdriver or wrench. Source IV brand PARs open the same way as ellipsoidals, while other PARs generally have a simple latch similar to a lunchbox latch and a hinged lid.

• 3

  Pull the old lamp straight out of the socket. Wiggle it back and forth if necessary. Don't worry about touching the glass unless the lamp is still good and you are simply changing to a different wattage. On PARs, you may have a porcelain base that attaches to the lamp. Pull this straight off. PARs may also have an open ring holding the lamp in place. Remove this by pinching the ends toward each other between your thumb and forefinger to shrink its diameter slightly, then pull it out the back of the instrument.

• 4

  Push a new lamp into the base or porcelain socket and push it in as far as it will go.

• 5

  Replace the base on the lighting instrument. For PARs, remember to replace the ring after you set the lamp back into the housing by reversing the process you used to take it out.

• 6

  Tighten the latch or bolt that holds the base onto the light. Plug the light back in.

Bayonet Bases (Fresnels)

• 1

  Unplug the lighting instrument.

• 2

  Open the front end of the Fresnel lighting instrument. Remove a screw or unhook a latch if necessary, then the lens and its housing will swing open on a hinge.

• 3

  Remove the old lamp by pushing downward on it and then twisting until the tabs that held it in place line up with the open spaces in the socket. Pull up and out to remove the lamp.

• 4

  Line the tabs on the base of the new lamp up with the socket openings, then press the lamp down and twist it in the opposite direction from the way you turned it to remove the old lamp. Keep twisting until you can't turn it any farther, then release. The direction for this varies by manufacturer.

• 5

  Close and latch the lens housing and plug the light back in.