Introduction: How to Change Fresnel Lamp Sockets


#2 Phillips Head Screwdriver

1/4 inch Flat Head Screwdriver

#1 Phillips Head Screwdriver

Replacement P28s Medium Prefocus Lamp Socket with Insulator

A small cup to keep track of parts


If you (like me) work in a small, old, or neglected theater space, you probably have a closet (or warehouse) full of old or broken lighting fixtures. In our case, we had over a dozen Colortran Theater fresnels with broken lamp sockets. With just a small investment of money (and a slightly less small investment of time) you can bring these excellent fixtures back to life and save yourself thousands of dollars in replacement costs.

These particular fixtures use what is known as a P28s Medium Prefocus Base to hold their lamps, and while it is easy to find lamp bases on the internet, it is important to note that not every fixture will fit every lamp base. For these Colortran fixtures, you need the Bryant model listed here: If you have Altman fresnels, there are lamp sockets marketed specifically for those fixtures which will fit them perfectly. No matter which manufacturer or model of light fixture you have, make sure that you are ordering the correct lamp base for your purposes.

This Instructable will be focused on the Colortran Theater Fresnel fixture, but the general procedure for changing the socket will be roughly the same no matter what type of fixture you are working on. You might consider using the process of replacing the socket to clean your fixtures, as well as it being a good opportunity to check for structural issues.

A word of caution: If you are not comfortable working with devices that carry electricity, don't. You are responsible for your own safety and the safety of the people who will come after you. On the other hand, you will also be responsible for how great your shows will look with your new stock of great fixtures. Enjoy!

Step 1: Remove the Lens Assembly

With the fixture placed lens-up on the work surface, unscrew the two long machine screws in the lens assembly hinge. Use the lens assembly clasp on the upper right side of the lens assembly to remove it, and set aside.

Step 2: Remove the Front Plate

Remove the remaining machine screws from the front plate of the fixture, remove the front plate, and set aside.

Step 3: Free the Bottom Plate

Turn the fixture handle side up, and remove only the two bottom center machine screws.

Step 4: Remove the Bottom Plate

Turn the fixture so the handle faces away from you, and gently pull the bottom plate towards yourself to reveal the underside of the lamp carriage.

Step 5: Unmount the Old Lamp Socket

Holding onto the lamp carriage, use the small #1 Phillips screwdriver to remove the two small machine screws that hold the socket on the lamp carriage. Be very careful to reserve these screws as they are very small, easy to lose, and typically must be reused with your new lamp socket.

Step 6: Remove the Old Lamp Socket

Gently pull the lamp socket out from under the lamp carriage, loosen both flat head contact screws on the bottom of the socket, and remove the wire leads from the socket.

Step 7: Inspect Old and New Lamp Sockets

With the socket removed, we can compare the old socket with the new. Note the corrosion on the contacts as well as the missing retaining flange on the old socket. Noting what has failed on old fixtures can help you more efficiently diagnose problems in the future.

Step 8: Attach the New Lamp Socket

Attach the wire leads to the contacts on the new socket, making sure to tighten the contact screws snugly with the flat head screwdriver. When reattached, place the insulator in the depression on the socket and using the reserved small machine screws, attach the socket to the lamp carriage.

Step 9: Reinsert Bottom Plate

Flip the fixture up as shown, and slide the bottom plate back into place, making sure that the lamp carriage slides into the rails on the bottom plate.

Step 10: Reattach Bottom Plate to Back Plate

Holding on to the bottom plate, rotate the fixture towards you, align the screw holes, and reattach the bottom plate to the back plate. Be careful to align the screw holes correctly, they are easy to strip or cross-thread.

Step 11: Reattach Front Plate

Flip the fixture so the open side faces you, align the front plate, and reattach it. Start with the corners, and make sure to check the alignment on the bottom and top plates carefully. Remember to leave the two screw holes on the left open for the lens assembly.

Step 12: Test Spot/Flood Knob and Reattach Lens Assembly

Take a moment to test your spot/flood knob for full range of motion, and if satisfactory, reattach the lens assembly with your two long hinge screws.

Step 13: Insert New Lamp and Test

Using a glove, insert a new lamp (in this case a 500 watt, long life BTL lamp), close the lens cover, and test your (hopefully) newly working fresnel fixture. Be sure to take a moment to bathe in the warm glow of a job well done.

Step 14: Good Job.

Thanks For Reading.