AIEL Shop Tips
PAR LIGHT OVERHAUL
|
|
Although somewhat supplanted by LED fixtures, the PAR remains a basic
lighting instrument in the entertainment lighting world, especially for
smaller productions. Its low cost, simplicity, light weight, variety of
sizes, high light output, and its long life are appealing to many lighting
personnel in the industry.
|
Instructions here will guide you through the
procedures to overhaul typical PAR fixtures.
|
INFORMATION BELOW MAY
NOT BE REPRODUCED
WITHOUT PERMISSION
FROM THE AUTHOR ©
|
Be aware neither Atlantic Illumination, nor its owner
and employees will be responsible for any problems
encountered as a result of following or not following
the procedures here. This is only a guideline. You
must decide the suitability of the steps given, and
be responsible for the results of your own work.
|
Topics
Preliminary
PAR maintenance is the simplest of the lot, because this light
is simple by design. It typically consists of an outer shell with
a yoke, accessories holder, and lamp access. Internally are
the electrics and PAR (Parabolic Aluminized Reflector) lamp.
The fixture itself has no reflector or lenses because they are
part of the lamp, although models exist with each component
being separate. LED units in place of the lamp, have a plate
upon which red, green and blue LEDs are arranged in rows.
Instructions given will lean toward the PAR 46 and larger
models, although some text will reference other designs.
Modify the procedures as required to fit your fixture type.
Read through this article before starting so you'll have an idea of what
is required and the tools needed. You may find that some procedures are
better done out of order for your particular model.
Regarding the refurbishment itself, this article assumes that the fixture
is to be completely overhauled. However, you may require to do only a part
of what is detailed here, so simply skip to the pertinent section(s). Read
through them before starting so as to perceive what will be required.
You may find that some steps are better done out of order for your
particular light or way of doing things.
If you are unfamiliar with the model you have, make notes or drawings,
or have an assembled fixture available for reference. Otherwise, given the
simplicity of the PAR fixture, these will likely be required only if you
are completely new to stage lighting fixture maintenance.
For those of you that may wish to print this page and use it to check
off each step as it is completed, a
Text Version is available.
|
Before starting the procedures, determine
by reading the entire article which of
these items to make available:
|
- Replacement Parts
- Alignment Cradle
- Alignment Screen
- Test Dimmer
- Newspapers
- Heat Shrink
- Heat Gun
- Small Parts Bottles
- Large Muffin Pan or
Parts Containers
- Bench Vice
- Bench Brush
- Screw Drivers
- Nut Drivers
- Diagonal Cutters
- Locking Pliers
- Wrenches
- Knife
- Fine-Toothed Flat File
- Narrow Scraper Tool
- Rubber Mallet
- Crimp Tool
and Connectors
- Electric Drill
or Bench Buffer
- Drill Bits
- Rotary Mini-Tool
(Optional)
- Variety of Wire Brush
Attachments (Brass)
|
- Cut-Off Garden Hose
- Plastic Soap Pads
- Steel Soap Pads
- Scrub Brush
- Tooth Brush
- Dish Detergent
- Emery Cloth
- Sanding Sponge
- Fine Steel Wool
- Spray Paint
(Heat Resistant for Metal)
- Paint Solvent
- Masking Tape
- Cardboard Mask
- Rayon or Cotton Batting
- Glass Cleaner
- Methyl Alcohol (Methanol)
- Distilled Water
- Soft, Lint-Free Tissues
- Penetrating Oil
- Lubricating Oil
- Oil Station Bin
- Paper Towels
- Silicone Lubricant
(Industrial Grade)
- High-Heat Wire Nuts
- Rags
- Permanent Marker
- Electrical Tape
(White and Black)
|
Set up a work space with proper lighting and the tools required. Refer
to our Work Area Setup article to help
with this. Provide a muffin tray or containers into which the parts from each
disassembly step wil go; number them. This will be a benefit when it comes
time to reassemble the unit as the parts can be selected in reverse-numbered
sequence. Lay clean newspapers on the bench to protect both it and the
fixture, and to contrast with small parts that might get dropped during
the processes that follow.
Now begin the overhaul itself:
DISASSEMBLY
A reminder that if you are new to this to keep track of the
disassembly by making notes. Use the numbered containers
or muffin pan to hold the parts removed during each step,
and have an assembled fixture available for reference.
Now do the following:
- Position the Light: With a room-temperature fixture,
first place it on the newspapered bench in an upright, face-down position.
Most have a lamp 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 should the fixture be in any position other
than face down.
If the fixture is smaller than a PAR 46 or is an LED model,
it will likely need to be placed horizontally on the bench so that there
is access to the lamp or LED element plate.
- Socket and Lamp Procedures: For the smaller PARs,
unscrew the lamp, or remove/unlatch the retainer to access the lamp
for removal. Some will have separate reflectors and lamps that are
retained by clips or a ring. LED models will need to have the LED
element plate removed, usually via screws around its perimeter.
For most PAR 46, 56 and 64 units, 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 socket and lamp in such a way that
penetrating oil can run down into the socket. Let this sit for a while
and then attempt to disengage the socket again. If it's completely seized
and the socket is one that is bolted together, unscrew these bolts and
separate the socket halves. You will then have to work to release the
contacts from the end prongs of the PAR lamp.
If they have become welded together, be prepared to possibly have to
destroy the lamp, the socket, or both. This is particularly so if the socket
halves are riveted, although you could attempt to drill out the rivets. If
you must purposely break something, try to save the more expensive lamp
unless it is burnt out.
Now take out the lamp. This is done either by holding back a release
while the lamp is lifted, or a retainer ring must be squeezed and moved
past nipples on the inside of the lamphouse. Then the lamp may be removed.
LED plates and some lamps come out the front of the fixture after removing
a clip or a series of perimeter screws. Place the lamp in your safe place,
as discussed in the Work Space Design
article.
During this procedure, don't be worried about touching the
bulb. You will be cleaning it later.
- Yoke Removal: You may prefer to do this step before the
lamp removal, which is fine. Just be sure to protect the lamp from damage.
With some models, the removal of internal nuts may be required to get the
yoke mounts free. In that case, the lamp may have to be removed first,
anyway. Regardless, if not already done, detach the yoke along with any
associated mounting hardware. Remove the clamp or stand adaptor and place
them aside. Retain the date tag (if there is one) and place it with the
lamp so it can be reattached or recreated upon reassembly.
- Electrical: Remove the plug if possible, and loosen the
electrical strain relief. Detach the ground lead from the fixture body,
placing small hardware into a conatiner with a locking cap such as a pill
bottle, and from there then into one of your parts containers. Most larger
PARs allow removal of the socket and wiring by pulling the line cord back
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 detach the electrics or tape them up for the fixture
painting phase of this overhaul. It is generally best if the electrics can
be completely removed, though. This will mean disconnecting the line cord
from the socket usually by removing crimp connectors or wire nuts. Loosen
the strain relief and pull the cord out through the body.
PAR fixtures with mounted sockets will require some
disassembly in order to get it out. Removing a rear cover might also be
required beforehand -- in some cases having to drill out rivets to do so.
It may be so difficult to remove some sockets of this type that they
might have to be left in place.
LED models will have to have their line cords disconnected
from their internal circuit boards, along with any data lines going to
fixture body XLR connectors.
- Final Disassembly: Now remove the strain relief. Detach 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 better to not have to deal with an access
cover flopping around. If its 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.
Remove any remaining brackets, mounts, fittings, and hardware. You should
now be left with just the body shell in one or more pieces.
INSPECTION
- Body: 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 blow from
a metal hammer. To protect finishes that are not to be painted, cover with
a thick, soft cloth.
Inspect the bolt mounts for the yoke; they should not
be worn or damaged. If so, then it means a trip to the machine shop to have
them re-threaded, unless you own a tap & die set. Note that some models
use a "grab plate" locking mechanism, so the yoke mounts are free to pivot,
thus stripped threads are less of a problem.
- Yoke: Look at the yoke. Note any burrs that should be
filed off, and if straightening will be needed. The latter can be done
using a vice to squeeze ripples flat, and as a clamp to permit reshaping
by hand.
RECONDITIONING
- Initial Restoration: If the fixture is very dirty, you
may wish to clean off the loose dirt with a bench brush, then skip ahead
to the "Washing" topic. Return here while it is drying to study the next
procedures.
For severe corrosion on the body or yoke, employ a narrow
scraper tool to remove the worst of it, then use a bench-mounted buffer
with a brass wire brush to redress these areas. (A brass brush is preferred
over steel so as to lessen the chance of gouging.) Because polished or
natural aluminum finishes are easily scratched, precisely focus the brush
on the bad spots if you plan to retain the aluminum look. Hold or secure
electrics that might still be attached in order to keep them away from the
rotating brush.
Should no bench buffer be available, use an electric drill
with a lockable trigger, and attach a suitably sized wire brush accessory.
Clamp the drill into a vise so that the brush sticks well out into the
open. You will find that clamping the drill and moving 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 this
clamping operation every time. Work gloves are recommended, as are hearing
protection, and goggles or a face shield.
Begin to buff the bad areas. Do not press too hard because
the wire bristles can score the metal. Use the side of the bristles for
finer work with less chance of marring your work. Use the scraper to
dislodge flaking paint, then buff the area underneath.
- General Body Buffing: Protect the electrics if they are
still attached. Begin to gently buff any painted areas so as to prepare the
finish for its repainting. The goal is to remove grime, surface rust, and
any patina that has accumulated while the unit was in service.
For those natural or polished finishes, buff with fine steel
wool, or you might try a commercial anti-tarnish product. Some surfaces will
also respond to a very fine sanding sponge -- you will have to test to see
which method works best without compromising the finish. Set aside prepared
items for washing.
- Hardware Refurbishing: Replace any severely rusted parts
that cannot be restored. Clean and buff the remaining metal hardware
including the pipe clamp or stand adaptor back to being shiny. Take them
apart to do this. Use a pair of pliers, preferably a locking type, to hold
smaller items. This will give you more control, and it will also distance
your skin from the rotating brush.
Be cautious not to distort these smaller parts by
over-tightening the plier locking mechanism. If locking pliers are
unavailable, use snub-nose pliers and grip them tightly as you manipulate
the item being buffed. Too loose a grip will see parts go flying due to
the speed and torque of the rotating brush.
- Hardware Protection and Lubrication: After buffing, protect
metal hardware with a thin coating of light machine oil, but use a
medium oil for threaded parts.
Keep oil from soaking into your work bench. A greasy bench is
not a good environment for lighting fixtures because oil will work its way
into areas where it is not wanted. As such, it is suggested to buy a
medium-sized plastic bin such as a dish pan to employ as an oil station.
To soak up excess lubricant, cover the bottom with one layer of an old
towel. Oil all metal components in the pan, turning them to assure full
coverage. Leave parts there until needed for reassembly, being sure to keep
the parts clustered into the same divisions as were in the individual
containers. If the bin is too small to do this, then only buff and oil each
section of parts just before reassembly.
For parts that do not have dust or built-up grime and so
don't need washing, you might now wish to skip to the
"Painting" procedures so that these first items will be
drying while you continue with the steps below.
WASHING
- Remove Jewelry: Before washing items, especially optical
components, remove rings, bracelets and watches to prevent scratches on
both the parts being washed and on your skin.
- Main Parts: Place non-oiled items such as the yoke and
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. Dislodge remaining rust with a soapy scouring pad. For
stubborn rust, use a sanding sponge or emery cloth with water. Rinse well.
(A cut-off, one-metre length of garden hose is good for this because the
end can be squeezed to exert higher water pressure.) Dry with an old towel.
Don't use a new one as rusty water will likely stain it. Hang the unit up
to air dry its inaccessible areas.
- Lamp: If there is a date tag written on the back, before
washing, record the information so it can be restored later. PAR lamps may
be washed in the sink with soap and water. If the lamp is very grimy, use
a steel soap pad to remove it. Rinse well. Place the lamp in your safe
place. If the electrical prongs are tarnished, use the bench buffer to
restore them.
- Metal Reflectors: If lens, lamp, and metal reflector are
separate, wash the reflector. Plastic soap pads can likely be used on metal
reflectors, but test on the back of the reflector to confirm it won't scratch
the surface. Keeping the pad well soaped, use a motion that follows the
curvature of the metal. If it polishes with no scratches, do the same on
the reflecting side. Otherwise, clean with a soft cloth and soap. Rinse and
dry.
For tarnished reflectors, you will have to decide if it's
better to have a smooth but tarnished reflector versus a shiny, scratched
one. In most cases, the plastic soap pad will produce a better surface,
even though there will be some scratching. I vote for the latter if it
reflects more light without too much scatter, rather than leaving it
tarnished.
If severely tarnished to the point that it may not be usable,
you can attempt to polish it with actual steel wool soap pads, or with
automotive rubbing compound. The worst ones will have to be taken to a
professional metal refinisher or be replaced.
- Glass Components: Handle non-coated glass lenses and
reflectors by their edges. Feel for rough sections that might cause cuts
so you'll be cautious around them while cleaning. Blow off loose dust using
a can of compressed gas or a large air bulb as used by photographers. With
a clean towel in the sink on which to rest glass components for protection,
rinse under warm water until no grit is left. Don't rub areas containing
grit; hose them off as soon as you feel it. You may apply moderate pressure
from the hose. Continue gently hand washing with soapy water.
Rinse the towel from time to time to keep it grit free. Be
careful that your slippery hands don't lose their grip and drop the item.
Glass components are expensive, so it is best to only have one at a time
in the sink to preclude breakage. Have a thick, clean towel on the counter
beside the sink to hold washed items while they air dry.
To remove film build-up, mix a small squirt of dish detergent
and water, and with clean, wet hands gently wash the reflector. Carefully
feel for rough edges that might cause cuts so you'll be cautious around
them while cleaning. If you feel grit, stop rubbing and rinse; then resume.
If the grime is particularly stuck, full-strength alcohol
can be employed if there is no coating. (See the "coated optics" warning,
next.) When finished, rinse and air dry. If you find some streaks are
left, you might repeat the process, but use distilled water as a final
rinse. Once completed, place glass reflectors into your safe place with
soft cloths or paper towels protecting them.
WARNING! Some glass reflectors and lenses have
coatings that increase their efficiency. These can be dulled or destroyed
if glass cleaner or undiluted alcohol are used on them. Use only
soap and warm water, or 10% alcohol and warm water, for cleaning.
Even though many glass components can handle glass cleaner and
full-strength alcohol, as a caution, use only soap and warm water,
or the 10% alcohol solution even if the manufacturer of the fixture states
otherwise. It's possible that someone could have replaced a lens or reflector
with one which coating cannot handle certain cleaners. If you suspect this,
follow the coated-optics cleaning instructions father back.
Whatever the material, when finished cleaning, rinse and air
dry. Place the lenses back into your safe place with cloths or paper towels
protecting them.
While components are drying, you may move on to
restoring the electrical parts you removed earlier.
ELECTRICAL
- Socket Assembly: Inspect the socket 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, which will have to
be drilled out. If you can get it apart, the contacts will be completely
exposed. Burnish off any corrosion there and inside the socket halves. If
the contacts remain severely discoloured, you probably should replace the
socket. Retain the porcelain halves as replacement stock for future broken
ones. Should wires detach from the contacts, they will need to be brazed
back on -- soldering often lets go because of the heat generated by these
lamps.
For screw-base versions as would be seen in a PAR 38 fixture,
use a very small, wire-brush drill attachment to allow access completely
into the socket. Buff the threads and button back to shiny. A rotary
mini-tool as used by hobbyists may be required to access sockets that
could not be removed.
Low-voltage PAR 36 and 46 models usually have slip-on
connectors or ring terminals at the lamp end of the line cord. If these
are tarnished, the latter can be buffed with the electric wire brush.
Slip-on terminal contacts are harder to access, but given their low cost,
they can be replaced using a crimp tool. Be sure to buy the right connector
size and type to fit the lamp's contacts, and use ones with heat-resistant
insulators.
- Line Cord and Covering: If the line cord is melted, frayed,
or brittle, it will require replacement. Some cords may be covered with a
fibreglass sheath. 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.
(Tape or heat shrink may not last in there if the temperature becomes too
high.) If the amount to be cut off will be excessive, make up the shortfall
with an appropriate length of sheathing coupled via heat shrink or
electrical tape. If using tape, wind at a 45-degree angle while pulling the
tape taut. Reverse direction and wind back over top of the first layer,
again at a 45-degree angle.
- Connector: Inspect the connector. Replace if cracked, has
heat damage to the plastic or rubber, or has badly discoloured pins that
cannot be restored. Otherwise, open the body to see if the wiring is tightly
connected and that there are no errant copper strands. When it comes time
to reassemble, make sure that the strain relief grips both the cable's
insulation and any outer sheathing. Buff the blades back to shiny.
- Asbestos: Should the fixture be an old one with asbestos
wiring, it is generally best to replace with a new line cord. Asbestos
conducts electricity when wet and is hazardous to breathe if it is
shedding. Put the removed wiring into a plastic grocery bag and send to
your local Hazardous Waste Facility. Some later fixtures used a
better-quality asbestos covering that does not shed; if the fixture will
be used indoors in a permanent installation, and if the asbestos has not
been compromised, you may reuse it unless local electrical codes forbid it.
More electrical work will be covered in the "Reassembly" phase, farther on.
PAINTING
Paint Choices: If there are parts that are rusted or
discoloured (other than electrical or the reflector), painting will be
required. The usual colour would be flat black. This is recommended for
all interior body surfaces in order to minimize unwanted reflections. The
paint chosen should be able to handle directly radiated heat. Barbeque
paint is a good choice. Buy a test can first! Some barbeque paints have
a flat black cap, but actually dry with some degree of shine.
For the exterior, you may want a different colour. This might be to
dress up the light, to better identify your lights from those belonging to
others, or to give your show a uniqueness if you like to have visible
fixtures. Even so, endeavour to stay with a darker colour to minimize
external reflections. A satin (semi-gloss) finish is recommended regardless
of the colour chosen.
Now gather your paint materials as given
in the preliminary list near the start
of this article and do the following:
- Preparation: Fixtures with a polished or natural finish
that are to be painted must have their surfaces roughed. Use a coarse
sanding sponge to dull all the areas that have never been painted. If not
already done, scour all painted areas with the bench buffer. You need not
take off all the old paint -- only that which is loose, and of course,
surface rust should be removed as previously discussed. Dust off the parts
with a bench brush. You may need to also wash them again.
- Segregate Areas: Being sure items are dry, begin by placing
masking tape over any areas to be protected from paint such as electrical
stickers, or screw threads. To facilitate tape removal, leave a tab on the
tape by folding a small bit of the sticky side back on to itself. If the
socket and line cord have not been removed, tape these, too. For screw-base
sockets that are still mounted, insert rayon batting to protect the threads.
Place tape over any other items that you do not want to receive paint.
- Painting Procedure: Put the items onto newspaper in your
booth or ventilated area, as discussed in the
Work Area Setup. Follow the instructions
on the can regarding optimal temperature and for re-coating. Shake the can
well and begin to make a base coat in even strokes. Stop the spray at the
end of each pass and then restart as the stroke returns. Blend each line of
paint with the previous in a manner that does not leave gaps of excessively
thin coats or ones that are too thick. Keep the overall coating thin. Allow
it to dry, then do a second coat, and a third one if necessary. Since fresh
paint can still be soft underneath, leave items to dry over night so that
the paint will cure. Repeat the process for the yoke and other parts
requiring paint.
After the base coats have dried, if the exterior is to be a
different colour, coat it using the technique above. Keep overspray out of
the interior. Partly to keep that different-colour paint outside, but also
to limit stray light reflections, it is suggested that the front of the
accessory holder and its inside runners be left flat black. This is easily
accomplished by leaving the fixture in a nose-down position for all of the
exterior paint work. Of course, if the holder has been removed, it makes
it much easier to paint it whatever colour you want without employing
masking techniques.
If the nose-down fixture position is not to your liking, a
hand-held cardboard mask may be used to keep spray from where you don't
want it. Even so, you might still have to touch up the inside
after the exterior has been completed. Allow the final coat to dry
over night to achieve a harder, more robust surface.
- After Each Painting Session: When completed painting for
the day, blow out the paint can nozzle by turning it upside down and
spraying until only propellant comes out. To lessen waste, I always do this
onto one of the lights just as I am in the process of finishing a coat.
When the can is empty, keep the nozzle in case future ones get clogged,
and send the can itself to Hazardous Waste.
REASSEMBLY
- Cautious Handling: There should now be a number of
sections and parts that are clean, non-damaged and possibly repainted.
Being careful of your new paint work, start to reassemble the fixture in
reverse order of the disassembly, 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.
- Body Assembly: Restore the lamp access cap along with the
hinge and its closure catch or fitting, if any of these had been removed.
The same goes for the accessory holder and/or its retainer. Check to be
sure that the rear cap aligns with the body when it closes, and that it
aligns with its closure strike. It may need to be gently warped one way
or the other to accomplish this.
- Restoring the Electrics: Do any remaining line cord work
not done before. This might include buffing and oiling the plug blades,
taping the cord and/or sheathing, and replacing terminals.
- Reinstalling the Electrics: For LED or separate-component
models, mount the circuit board and required brackets. For all models,
install the strain relief and route the line cord through the body. Then
for detachable plugs, connect the hot and neutral leads of the line cord
to the circuit board, or to the socket and using an insulating wafer, if
required. Thread the line cord out through the strain relief and attach
the ground lead to the ground terminal. If fibreglass sheathing is to be
used, slide it on to the line cord and position it. Reinstall the socket
assembly and pull excess line cord out through the body, leaving a bit
of slack. Connect the line cord leads to the plug and slip the outer
sheathing into the plug's strain relief. Tighten all.
For line cords with plugs attached, slip heat shrink onto
the cord followed by the outer sheathing, after which secure the
sheathing at the plug body by taking the heat gun to the shrink. Draw the
line cord through the strain relief and into the body. Trim sheathing to
remove slack.
Attach the hot and neutral leads to the socket, or attach to
its leads with wire nuts or crimp connectors. Be sure to observe electrical
polarity when rewiring: In Canada, the hot (black) lead goes from the
center contact of the socket, down the line cord and onward to the brass
screw of the plug. The neutral (white) lead is connected to the silver
screws, the ground lead to the ground post on the body of the fixture and
to the connector's green screw. Symmetrical PAR sockets, such as the Mogul
End Prong and Medium Side Prong ones, do not observe polarity. The hot and
neutral leads may go to either side, but should still go to the correct
terminals in the connector. Silicone the socket's contacts if this has not
already been done.
Remove any slack in the sheathing and tighten the body strain
relief. When the light is fully assembled, the sheathing should run from
the socket assembly (allowing for the splay of individual leads), along
the line cord and into the plug's strain relief at the other end. If the
plug is the moulded type, the sheathing should go up to it and be secured
with tape or heat shrink.
- Brackets and Hardware: Replace any remaining brackets or
fittings, and lubricate/protect any hardware that had been not done
before this point. Keep oil from affecting non-hardware surfaces. For
separate-component models, mount the reflector and socket, and then,
if used, the lens-turning mechanism. Use silicone in the socket and on
the lens turner.
ELECTRICAL TESTING
- Continuity Test: Use the `ohms' setting of your multimeter
to confirm a continuous electrical path from plug to socket. Check the
neutral and ground paths, as well. `Zero' ohms should be the reading.
Diagnose and fix any problems.
- Shorts Test: Test for shorts between hot and neutral, and
from each conductor to the metal fixture housing. If the meter reads
anything but "infinity", there are problems. Diagnose and fix before moving
on.
- Lamp Test: You may elect at this point to install the
lamp as an additional test, but can wait if more parts have yet to be
placed. Do a lamp continuity test before putting it in. If all is
well, move on to the alignment.
ALIGNMENT
Install any remaining parts, but you may choose
to leave the yoke and pipe clamp until after
the next procedure has concluded. Install
the lamp, if you have not already done so.
- Alignment? No adjustment is required for PAR fixtures
because the lamp/reflector/lens is a pre-aligned unit. Regardless, the
lamp and/or its retainer could be out of place, as could the components
of models using separate lamp, reflector and lens. Therefore:
- Lamp: Test the lamp with your ohm meter, and if not already
done clean the bulb. If the reflector, lens and lamp are separate components,
use methyl alcohol to remove finger oils from the bulb. PAR lamps may be
cleaned with soap and water or glass cleaner, as discussed earlier.
(Silicone may be necessary for the PAR bulb. See the "Final Procedures"
section farther on.)
- Support the Fixture: Begin by setting the light in the
alignment cradle so that it is level, and the center of the fixture opening
aligns to the screen's center point. Plug the fixture into a dimmer and
reduce light output to the lowest setting that still produces a bright
oval or circle. Lowering the voltage is done to lessen the chance of
lamp burnout during possible rough movement as its alignment is adjusted
The area of light should be directly opposite the front of
the fixture. If it is not, look to see that the lamp is seated properly
and that its retainer clip or ring is in the correct position. Adjust as
necessary.
For 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 directly onto the fixture's interior on the way out.
For separate components, check to see that the reflector is
seated and retained properly, and that the socket and lamp are aligned
within the reflector. Look to see that the lens is not canted to one
side. Adjust as necessary.
FINAL PROCEDURES
- PAR 46, 56, 64 Lamp: Because the larger PAR lamps project
an oval beam pattern, they must be able to rotate to position the pattern
onto what is being lighted. Confirm that the lamp can rotate freely. If
not, use a paper towel to apply silicone to the edge of the bulb where
it contacts the fixture so as to allow smooth turning. If the lamp binds,
you may have to bend the metal "shelf" on which the lamp rests, or may
have to gently squeeze the fixture to bring it back to round.
- Separate Components: For those models that have a
rotating lens or lens holder, make sure it can turn freely. Silicone
the lens edge or rotation mechanism for smooth operation.
- Date Tagging: This is an important step because the tag
will give an indication of lamp service life. If the time period is less
than expected, there may be a problem with the fixture, its location, or
its input voltage.
Date tag the lamp by writing on the back with a permanent
marker. Write near the edge of the reflector where heat is lowest. Allow
for the retainer ring or mechanism to not block the tag. Do this twice,
180-degrees opposite one another. This is so that the date tag can be
read easily regardless of the lamp's rotation.
For separate-component models, write the date on white
electrical tape and stick it to the inside of the yoke on one of its
vertical surfaces -- usually the one opposite the tilt-lock knob. Be
consistent so that you and your crew will know exactly where to look.
Don't use the underside of the top of the yoke because heat here will be
greater than along the sides when the fixture is hung in its typical
orientation. Make the tape long enough to have space for two dates. This
way, it only needs to be renewed every second lamp replacement.
You now have a refurbished PAR fixture
of which to be proud. ENJOY!
(Now do the rest of them...)
This Article is
Available in a
Plain Text Format
for Your Archives
|
Click the Download button. The article will either be
saved directly to your computer in text format or you
will see the text on your screen. If it is the latter, right
click within it and select Save As or Download.
Arachne users can press `F2'.
Name the file "Main-PAR.txt".
|