Atlantic Illumination Entertainment Lighting

AIEL Shop Tips

PAR LIGHT OVERHAUL

(Image Left: PAR Stage Light)     The PAR is the basic lighting fixture of the entertainment lighting world, especially for the touring musical act. It is a simple fixture typically consisting of an outer shell gel frame holder, and lamp access, electrics, a PAR (Parabolic Aluminized Reflector) lamp and a yoke. The fixture itself has no reflector or lens as these are integral to the lamp, although there are some models where the components are separate. Sockets are usually medium screw base, medium side prong, or mogul end prong, although some use screw or spade terminals. LED models have a plate in place of the lamp. On this are LEDs arranged in rows, typically every third one is red, green or blue for colour mixing purposes.

    Each lamp comes with a specific lens which may give a wide flood, medium flood, narrow spot or very narrow spot as the most typical beam spreads. There are others. Wattages range from 30 to 1000, but the typical stage units run from 90 to 1000, with sizes for these being PAR 38, 46, 56 and 64. The size numbers are based on an old measurement system of eighths of an inch. Thus, the ~200 millimetre PAR 64 has a bulb face in old measurements of 8 inches.



Table of Contents for this Page

Preliminary
Disassembly Inspection and Reconditioning Electrical
Painting Reassembly and Lubrication Alignment





INFORMATION BELOW MAY NOT BE REPRODUCED
WITHOUT PERMISSION FROM THE AUTHOR ©

Be aware that neither Atlantic Illumination, nor its owner or
employees will be responsible for any problems encountered as
a result of following or not following the procedures here. This
is strictly a guideline. You must decide the suitability of the
instructions and be responsible for the results of your work.

 

* PRELIMINARY

    PAR fixture maintenance is the simplest of the lot. This article assumes the fixture a non-LED model and is to be completely refurbished, and thus will be disassembled. However, you may only require to do a part of what is outlined here, so simply skip to the pertinent section(s). The instructions on this page can be adapted if you have LED models. Essentially, one would remove the LED plate and electrics and follow the rest of the overhaul procedures.

    Read through this article before starting so you'll have an idea of what is required. You may find that some steps are better done out of order for your particular model. Also, make notes or drawings, or have another unassembled fixture available for ease of re-assembly if you are unfamiliar with the particular model on which you are working. However, given the simplicity of the fixture, this will only likely be required if you are completely new to fixture maintenance.

    Set up a work space with proper lighting and the tools required. See our Work Area Setup article to help with this. Have some numbered containers available in which to place the parts from each disassembly step. This will benefit you when it comes time to put the unit back together again. Lay some clean newspapers on the bench to protect both the bench and the fixture. The light colour also helps to contrast small parts which may be dropped during the overhaul operation, and makes for a nice work surface.


    You should have these items available:  

* DISASSEMBLY

    A reminder that if you are new to this to keep track of the disassembly by making notes, using numbered containers or a muffin pan to hold the parts removed during each step, and by having an assembled fixture available for reference.

These instructions are for working on the larger PAR
fixtures that have push-on/pull-off sockets. For LED
or screw-base units, modify the instructions accordingly.


  1.     With a room-temperature fixture, first place it on the bench in an upright, face-down position. Most have an access door at the rear. Open this. Be cautious: Some poorly designed fixtures only secure the lamp via this door. Opening it may send the lamp crashing to the floor if the fixture is in any position other than face down.

  2.     Carefully pull the socket free from the lamp's connectors. Hopefully, it won't be seized. If it is, you will need to turn the whole unit in such a way that penetrating oil can run down into the socket. Let this sit for a while and try to disengage the socket again. If it's completely seized and the socket is of the type that is bolted together, unscrew these bolts and separate the socket halves. You will then have to work to separate the contacts and the end prongs of the PAR lamp.

        Be prepared that you may have to destroy the lamp, the socket, or both if they have become welded together. This is particularly so if the socket halves are riveted together. If you can, try to save the more expensive lamp unless it is burnt out.

        Now remove the lamp. This is done either via holding back a release while the lamp is taken out, or a retainer ring must be squeezed and removed past nipples in the side of the lamphouse. Then the lamp may be removed. Place it in your safe place, as discussed in our Work Area Setup.

        For those models of PAR fixtures that use ellipsoidal- or fresnel-style lamps and sockets with separate reflectors and lenses, you will have to remove each separately. Place breakables in your safe spot.

        During this procedure, don't be worried about touching the bulb. You will be cleaning it later. Put the lamp or assembly in your safe place.

  3.     Now detach the yoke, remove any clamp or stand adaptor, and place them aside. You may prefer to do this step before lens and lamp removal, which is fine. Just be sure to protect the lens and lamp from damage. With some models, the removal of internal nuts may be required to get the yoke free. In that case, the lamp will have to be removed first, anyway.

  4.     Remove the electrical plug, if possible. Take off the electrical cord connector. Most PARs allow removal of the socket and wiring this way. It is done by having the line cord pull through the body, permitting the socket to be taken out with line cord intact. For those fixtures with moulded plugs, you will have to decide if you want to remove the electrics or tape them up for the fixture painting phase of this overhaul.

  5.     After pulling the cable out, remove the strain relief. Now remove the lamphouse access cover (door) if possible. This step may be unnecessary if the fixture is in good shape. Otherwise, for straightening or for certain other maintenance purposes, it's handy to not have to deal with an access cover flopping around. If the hinge is welded and the pin cannot be removed, the access door will have to stay with the main fixture body for the rest of the overhaul.

  6.     Remove any remaining brackets. You should now be left with just the body shell.
 

* INSPECTION and RECONDITIONING

  1.     Look at the body to see if there are any dents or bent parts. Repair as necessary. To pound out dents, use a wooden form and rubber mallet to lessen metal damage as compared to a direct hammer blow. Inspect the screw mounts for the yoke; they should not be worn or damaged. If so, then it means a trip to the machine shop to have it re-threaded. Note that some models use a "grab plate" locking nechanism, so the yoke mounts are free to pivot, thus stripped screw mounts are less likely to be a factor.

  2.     Do the same for the yoke. Note any burrs that should be filed off, and then straighten the yoke, if necessary.

  3.     Now place the body into a plastic set tub or use rubber mats to protect an enamel one. Scrub the unit using hot water and dish soap. Use a tooth brush to get into small areas. Remove rust with a wool-type soapy scouring pad. For stubborn rust, use a sanding sponge or emory cloth. Rinse. (A one-metre length of garden hose is good for this.) Dry with an old towel. Don't use a new one as some rust will likely come off. Hang the unit up to air dry inaccessible areas. Repeat this procedure for the yoke.

  4.     For a severely corroded body, and for tarnished hardware, employ a narrow paint scraper and use a bench grinder with a wire brush to buff the finish. A brass brush is preferred over steel. If no grinder is available, use an electric drill with a lockable trigger. Clamp the drill into a vise. You will likely find that clamping the drill and holding the parts against the rotating brush works better than clamping the parts. It saves having to clamp and unclamp each part, and having to put the drill down to do the re-clamping. Use a pair of pliers, preferably the locking type, to hold small parts. This will give you more control and also keep your skin away from the rotating bristles. Work gloves are recommended, as are hearing protection and goggles or a face shield.
        (You might now wish to skip to the "Painting" section so that the first coat on the fixture body will be drying while you continue with the steps below.)

  5.     Clean and buff all metal hardware including the pipe clamp or stand adaptor. Take the clamp apart to do this. Repaint as necessary. Replace any severely rusted parts. Oil the hardware with a light machine oil. Polished aluminum can be buffed with fine steel wool or a commercial anti-tarnish product.

  6.     PAR lamps may be washed in the sink with soap and water. If reflector, lamp and lens are separate, wash each in turn. Wool soap pads may be used on metal reflectors, but test on the rear to confirm it won't scratch the surface. Use a circular motion. If it polishes with a minimum of scratches, do the same on the front. You will have to decide if it's better to have a smooth but tarnished reflector versus a shiny, scratched one. I vote for the latter if it reflects more light without too much scatter, rather than leaving it tarnished. Rinse and dry.

        For glass reflectors and lenses, use only soap and water and clean hands. Watch for rough edges that might cause cuts. Some glass optics will have coatings that increase their efficiency. These can be destroyed if glass cleaner or alcohol are used on them. Use only soap and warm water. Whatever the material, when finished rinse and air dry. Place glass items into your safe place with cloths or paper towels protecting them.
 

* ELECTRICAL

  1.     Move to the socket assembly. Inspect the contacts. For side and end-prong versions, this can often be done by removing the screws and separating the socket halves, unless rivets were used. If it comes apart, the contacts will be completely exposed. Burnish off any corrosion there and inside the socket halves. If the contacts remain severely discoloured, you should replace the socket. For screw-base versions as would be seen in a PAR 38, use a smaller drill attachment to allow access right into the socket. PAR 36 models often have slip-on connectors or ring terminals. The latter can be burnished with the electric wire brush. Slip-on contacts are harder to access, though. Given their low cost, they can be replaced using a crimp tool. Be sure to buy the right size and type to fit the lamp's contacts.

  2.     Should the line cord be melted, frayed, or brittle, it will require replacement. Some may use fibreglass sheaths. Replace or repair as necessary. If the damage to this is external to the fixture body, you may use electrical tape or heat shrink. If it's internal, cut off the bad part and slide a good section inside. Make up the shortfall on the other end with an appropriate length of sheathing coupled via heat shrink or electrical tape. When the light is fully assembled, the sheathing should run from the socket assembly, along the line cord and into the plug at the other end.

        If the fixture uses asbestos wiring, install a new line cord. Asbestos conducts electricity when wet and is hazardous to breathe. Put the wiring into a plastic grocery bag and send to recycle or to your local Hazardous Waste Facility.
 

* PAINTING

    Should any parts be rusted or discoloured (other than electrical or the reflector), painting will be required. The usual colour would be flat black, which I do recommend for all interior parts in order to minimize unwanted reflections. The interior paint should also be one which can handle directly radiated heat, such as barbeque paint.

    However, you may consider another colour for the exterior to dress the light up or to better identify your lights from those belonging to others, and to give your show a uniqueness. Even so, try to stay with a darker colour to minimize external reflections. I recommend a satin (semi-gloss) finish regardless of the colour chosen. Now, gather your paint materials as per the preliminary list near the start of this article and do the following:


  1.     Being sure it is dry, place the body in your paint booth or area, as discussed in the Work Area Setup. Note that natural and polished aluminum will need to be dulled with sandpaper and a base coat (aluminum primer) applied before the final colour is put on. If you intend to leave this finish, polish it with fine steel wool or a fine sanding sponge.

        Shake the spray paint can well and begin to coat the interior in even strokes, stopping the spray at the end of each pass and then re-starting as the stroke returns. If the exterior colour is the same, you may also coat accessible areas at this time. Keep the coat thin. Allow it to dry and then do a second or third coat, if necessary, following the instructions of the can regarding re-coating. Use paint solvent to clean overspray. Allow to dry. Repeat for the yoke and any other parts requiring paint.

        If the exterior is to be a different colour, after the interior has dried, coat the former using the technique above. Keep overspray to the interior to a minimum. You may have to touch up the inside after the exterior has been completed. Allow to dry overnight to get a harder, more durable surface.
 

* REASSEMBLY and LUBRICATION

  1.     You should now have a number of sections and parts which are clean, non-damaged and possibly repainted. Being careful of your new paint work, start to reassemble the fixture in reverse order, beginning with any internal sections. Regarding paint which is dry, but fresh, it may take a day or so for it to harden completely, hence the caution when handling.

  2.     Reinstall the socket assembly along with any strain reliefs and pull the cable through the body. Ensure any outer covering or sheathing goes inside the plug's strain relief and tighten all body and strain relief screws. Adjust the sheathing so that the slack goes inside the PAR body and up to the socket. Tighten the socket strain relief if one exists.

  3.     Replace any internal brackets or fittings and lubricate all hardware with a light oil. Keep oil from soaking into your work bench. An oil soaked bench is not a good environment for lighting fixtures because it will work its way into areas where it is not wanted.


  4.     Restore the lamp. If the reflector. lens and lamp are separate components, clean the quartz bulb with methanol alcohol to remove finger oils. PAR lamps may be cleaned with soap and water or glass cleaner, as discussed earlier. (Silicone may be necessary. See the "Alignment" section next.)

  5.     Do the final assembly using the remaining parts, but you may elect to leave the yoke and pipe clamp off until after testing is done.
 

* ALIGNMENT

  1.     No alignment is required for PAR fixtures because the lamp/reflector/lens is a pre-aligned unit. However, test the light. Shine it onto a white screen and check the focus. Most PAR lamps have an oval beam pattern and can be rotated to align that pattern with what is being lit. Confirm that these lamps can rotate freely. If not, silicone the edge of the bulb where it contacts the fixture so as to allow smooth turning. For fixed lamps, such as PAR 36 and 38 models, ensure that the socket and/or lamp is seated properly to allow the light to exit the fixture in a straight line without shining on to the fixture's interior on the way out.

        For separate components, be sure the reflector is seated properly and that the socket and lamp are aligned within the reflector. Test that the lens can turn freely. Silicone the lens edge or rotation mechanism for smooth operation.

You now have a clean, operating, properly aligned
fresnel fixture ready to work for you. ENJOY!
But wait... don't enjoy too much. You have more
lights and equipment to overhaul. (-:



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