AIEL Shop Tips
The ellipsoidal or profile spot is a favoured light
of the theater. It produces a soft-edged
or sharp beam via plano-convex or
step lenses that is able to be shaped
using internal shutters. Patterns (gobos)
are able to be projected with this fixture. Typical
wattages are 300 to 1000, but can go outside of this.
The instructions provided in this guide will take
you through a complete refurbishment of a typical,
non-LED ellipsoidal. Should only part of what is given
be required, simply go directly to the pertinent section(s).
Realise that you may have to modify these instructions in order
to fully suit the makes and models of the fixtures in your inventory.
INFORMATION BELOW MAY
NOT BE REPRODUCED
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.
Because the ellipsoidal has more parts, its complexity is greater
than that of a PAR or fresnel. Its precise optics and beam quality
demand a more critical calibration. As such, these fixtures exhibit
the worst impairment of ability when they go out of alignment or
their components deteriorate. Due to all of this, ellipsoidals will
suffer most from lack of upkeep, meaning their maintenance
is the most involved of the basic stage lighting fixtures.
There are a great number of variations in ellipsoidal
design. This instructional will lean toward the basic
styles, so you may have to modify what you read
so as to match your make and model of fixture.
This article assumes that the fixture is to be completely overhauled.
As mentioned though, your requirements may entail only part of what is
detailed here, so simply review the relevant section(s). Regardless, before
starting, read through everything that follows so you'll know all of what
is expected, and will realise what tools and supplies will be required.
Make notes or drawings as to what parts are associated with a given
procedure -- there are many of them, so have lots of containers and a large
muffin pan to hold the components from each step of disassembly.
Even more so than with fresnel and PAR lights, an assembled fixture
should be available as a reference during the overhaul process should
you not be familiar with the particular model on which you are working.
You may also find that some steps are better done out of order for your
particular light or way of doing things.
Before you begin with the procedures, determine
which of the items below to make available:
- Replacement Parts
- Alignment Cradle
- Alignment Screen
- Test Dimmer
- Heat Shrink
- Heat Gun
- Small Parts Bottles
- Parts Containers
- Large Muffin Pan
- Bench Vice
- Bench Brush
- Small Anvil
- Screw Drivers
- Nut Drivers
- Diagonal Cutters
- Locking Pliers
- Fine-Toothed Flat File
- Narrow, Metal Paint Scraper
- Rubber Mallet
- Steel Hammer with
a Flat Face
- Electric Drill
or Bench Buffer
- Drill Bits
- Rotary Mini-Tool
- Variety of Wire Brush
- Plastic Soap Pads
- Steel Soap Pads
- Scrub Brush
- Tooth Brush
- Dish Detergent
- Cut-Off Garden Hose
- 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
- Methanol Alcohol
- Distilled Water
- Soft, Lint-Free Tissues
- Penetrating Oil
- Lubricating Oil
- Oil Station Bin
- Silicone Lubricant
- Crimp Tool
- High-Heat Wire Nuts
- Paper Towels
- Cloth Towels
- Permanent Marker
- Electrical Tape
(White and Black)
Set up a work space with proper lighting and the tools required. See
our Work Area Setup series of articles
to help with this. Have the numbered containers and muffin pan available
for placing the parts from each phase of the disassembly. This will be of
benefit when it comes time to put the unit back together. 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 procedures that follow.
Now begin the overhaul itself:
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:
- Initial: Work with a room-temperature fixture and be sure
that the shutters are pushed inside to lessen the likelihood of them getting
First, take off the yoke. With some models, the removal of
internal nuts may be required to get it off. Some techs wait to do the
above until after the next two steps. If you wish to delay, ensure during
movement that the still-attached yoke and clamp do not damage anything on
the bench. It's easy for an unsecured yoke to swing unexpectedly and hit
something, or to jam a finger between it and the bench or the fixture
itself. Now remove any clamp or stand adaptor, and place it aside.
- Lens System: If your model does not have an internal
track/holder for the lens(es), remove the focus hardware and slide the lens
tube out of the body. Take the lens(es) from the tube either by removing a
retainer ring or clips, rubber saddles, and any spacers. Place the lens(es)
in your safe place as discussed in the
Work Space Design article and set aside
the tube and spacers. Place hardware into a numbered container. If the lenses
are internal, you will have to wait to remove them during the body
disassembly stage. If the front accessories holder is removable, take it
- Lamp House: Remove the lamp cap and electrics. This is
typically done by undoing one or more retainer screws or knobs and removing
the assembly. For some models, there may be an access door for lamp
replacement, but its mount and electrics often won't be able to be removed
until the body is taken apart.
Take out the lamp but don't worry about touching the bulb. You
will be cleaning it before re-insertion during the reassembly stage near the
end. Put it in your safe place. Set the cap aside with socket and line cord
intact for the time being. You will not be dissembling this now but will
do it during the electrical procedure. Keep any associated light shields or
hardware with it.
- Yoke: Now, if not already done, detach the yoke and 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
- Shutter Module: This is typically a self-contained unit,
but its components can also be mounted within a section of the body; if so,
these may not get removed until the next step.
If the module is separate, remove it and begin to dismantle.
Closely note the order and orientation of the separator plates and any
hardware. Some ellipsoidals have spring-tensioned shutters and it's easy to
lose this hardware during disassembly because there can be a lot of it, so
be vigilant here. Pay attention to the order of this tensioning hardware
and put all into a small container of its own.
Some modules have shutters that cannot be removed until
their knobs are taken off. If these are riveted, drill them out in order
to remove. Otherwise, take the knobs off by unscrewing their hardware.
Place all shutter assembly components into their own container, and small
hardware into a capped container such as a pill bottle.
- Body: If your model has a hinged reflector housing, remove
it now and disassemble its internal components. If not, remove the remaining
internal brackets and mounts. In order to do this, you may have to take
apart this section of the body, or remove access panels. The shutter
components may be taken out now if you have not already done so.
Continue until the remainder of the fixture is apart,
stressing the importance of noting the order and orientation of all parts
and hardware. Remove remaining electrical components and strain reliefs
if they were not part of the cap. You should now have an empty body
shell in two or more main sections.
- Body: Look to see if there are 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 steel hammer.
Inspect the threaded 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 associated with the locking mechanism 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
- Reflector: Have a look at the reflector. If it's badly
tarnished and can't be improved as described in the "Washing" section, it
will have to be replaced or sent to a metal refinisher.
- Shutter Plates: These should be flat and have a smooth
finish. Some bends can be straightned as will be discussed, but the worst
will have to be replaced.
- Electrics: These will be inspected during the "Electrical"
- Initial Restoration: If the fixture is very dirty, you
may wish to remove loose dirt with a bench brush, then skip ahead to
the "Washing" topic. Return here while it is drying to study the next
- Main Component Buffing: For flaking paint and/or a
severely corroded body and/or yoke, employ a narrow paint scraper to
remove the worst of it, then use a bench-mounted buffer with a brass
wire brush to redress the finish. (A brass brush is preferred over
steel so as to lessen the chance of gouging.)
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 out well 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 the finish. Use the scraper to
dislodge flaking paint, then buff the area underneath.
- General Body Buffing: Begin with any painted areas so as
to prepare the finish for its repainting. You need not take off all the old
paint -- only that which is loose. Of course, rust should be removed, too.
The main goal is to remove grime, surface rust, and any patina that has
accumulated while the unit was in service. Continue until all parts are
corrosion and tarnish free. Dust off the components with a bench brush. 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 thickness of an old
towel. Cut large towels to fit. 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 groups
as were in the individual containers. If the bin is too small to do this,
then only buff and oil each group of parts just before reassembly.
- Shutter and Plate Work: Straighten the shutters on an
anvil or a flat, hard surface such as found on some bench vices. Use a
broad-head, metal hammer to do so. Due to the nature of the stainless
steel used, you likely will not get shutter plates to be absolutely flat.
Replace those that are severely rippled because they will bind or jam
Now buff until very shiny, being cautious not to score them.
Use the side of the brass wire bristles so as to not have this happen.
Finish with fine steel wool to achieve as smooth a surface as possible. Do
the same for the separator plates. Set all aside for reassembly.
- Lens Tube: Buff painted parts to remove loose paint and
corrosion. For tube sections that are unpainted, polish with a fine sanding
sponge and complete with steel wool to achieve a silky-smooth finish.
- Remaining Items: Clean and recondition hardware and
items not already done, such as the lamp cap. If it requires painting,
first review the electrical section regarding disassembly. As always,
replace any severely rusted parts if they can't be restored. Put
rejuvinated hardware that won't be painted into the oil bin and coat
with a light, protective oil.
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.
- Main Parts: Place non-oiled items such as the yoke and
body sections into a plastic set tub, or use rubber mats to protect an
enamel one. Scrub items one at a time using hot water and dish soap.
Use a tooth brush to get into narrow 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 increase water
pressure.) 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.
- Metal Reflectors: Place the reflector into the sink. Hose
off the main dirt first. Use a plastic soap pad to clean the back of the
reflector as a scratch test. Move the pad with a motion that follows the
reflector's shape. If it polishes with no scratches, do the same to the
front. If scratches appear from the test, you will have to decide if it
is better to have a 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. If the pad is not suitable, substitute
a clean, soft cloth or sponge with lots of dish soap. Rinse and dry.
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. You may apply moderate
pressure from the hose. Rinse the towel from time to time to keep it grit
free. Be careful that your slippery hands don't 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, do the above and then mix a squirt
of dish detergent and warm water in a container. With soapy hands, gently
wash each wetted component in a motion that follows its contour. Feel for
grit that might scratch, and for rough edges that might cause cuts to your
hands. Don't rub areas with grit; hose them off as soon as you feel it, then
continue the hand washing with soapy water. Step lenses often have
black-painted risers. Be careful not to remove this coating.
If the grime is particularly stuck, full-strength alcohol
can be employed if there is no coating. (See the "Coated Optics" warning,
below.) 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
While components are drying, you may move on to
restoring the electrical parts you removed earlier.
- Lamp Cap: Inspect the socket assembly and electrics. If
there are no problems and the cap is not to be painted, move on to look at
the line cord.
Otherwise, prepare to remove the socket and inspect the
contact screws. Note the alignment screw positions; count the number of
visible threads and make a note so that during reassembly you can thread
each screw back to this same point. These will become the starting points
for the alignment procedure later on.
Clean off any corrosion associated with the socket. If it
remains severely discoloured, you should replace it. (Discoloured sockets
can contribute to reduced lamp life.) During replacement, consider renewing
the insulator wafer (if one is required) as located under the socket. It
should not be damaged, split, or missing.
Clean off the socket mount and inspect for damage. Repair as
necessary. If it's rusted, it will have to be scraped, buffed, washed, and
possibly painted with a heat-resistant finish. (Follow the steps under
"Painting", farther on.)
- 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 the first layer, again at a
- Connector: Inspect, and 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 discussed in the "Reassembly" phase, farther
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: Mask any things not to be painted such as
electrical stickers, screw threads, or lens barrels that must slide without
guide tracks. To facilitate tape removal, leave a tab by folding a small
bit of the sticky side back on to itself.
- Lamp Cap: If the lamp cap is to be painted, it is best to
fully remove its socket, wiring, and hardware. If this can't be done, or
you don't want to do this, mask all parts not needing paint. Be aware that
this can be tedious given the number of parts involved and how close
together they are. Pay particular attention to the socket by wrapping it
and covering over the opening. You may wish to insert rayon batting into
the socket to shield the threads and button.
- Painting Procedure: Put the items onto newspaper in your
booth or ventilated area, as discussed in the
Work Space 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 segregate the outside paint from the interior, 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 whatever colour you want without employing masking
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.
- 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, 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.
- Shutter Module: Pay particular attention when assembling
the shutter module. Its components must be put together in exactly the right
sequence and orientation. It is easy to mis-order the components, especially
any spring hardware. Shutter blades must line up properly with their slot
openings to the exterior, so their stacking order must be correct. Start
all screws before final tightening so as to allow for slight adjustments.
Restore the shutter module to the body.
- Reflector Assembly: Mount the reflector and any aperture
components. Be sure orientation is correct. As above, start all screws
before final tightening.
- Lens Assembly: Gently use a soft cloth to remove any finger
prints or smudges from lenses that happened after the washing process, or
repeat the cleaning process and use distilled water as a final rinse.
Remember to keep glass cleaner and alcohol away unless you are absolutely
sure the lens has no optical-enhancement coating. Restore the lens(es) to
the tube or internal track/holder using any required separator elements
and rubber saddles. Note that in some models, the separators must be
oriented to allow the operation of focusing devices or the insertion of
Confirm that each lens is loose! Do not place retainer clips or rings
hard against them. They must have room to expand during operation. Place
the lens tube into the fixture. Silicone the tube where it contacts its
guide tracks or the fixture itself. Be careful not to transfer silicone
to unwanted surfaces.
Mount the outer lens tube with any extension. Be sure they
are correctly oriented in the vertical and horizontal axes so that the
accessory holder's opening will be up, and that any slots for knobs are
in the correct positions. Attach the accessories holder, if not already
captive to the outer lens tube. Attach the holder's spring retainer if
there is one.
- Restoring the Electrics: Do any remaining line cord and
socket work not done before. This might include buffing and oiling the
plug blades, taping or heat-shrinking the cord and/or sheathing, and
replacing electrical terminals.
If the lamp cap was taken apart, put it back together by
starting with the strain relief unless it's the "crimp" type. These black
plastic reliefs can be mounted near the end of the procedure. Connect
the line cord to the socket. 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 then to the connector's
Symmetrical sockets, such as the G9.5 (Medium Two Pin),
do not observe polarity. The hot and neutral leads may go to either
terminal, but should still go to the correct terminals in the connector.
Poke the line cord with any sheathing through the strain relief in the cap
and attach the socket to its mounting plate. This in turn is attached to
the cap via its alignment screws. Reference your note regarding the number
of screw threads that are to be visible.
Install or tighten the strain relief and pull sheathing slack
toward the plug end of the line cord. Restore the plug to the cord, being
sure to observe electrical polarity. Pull excess sheathing into the plug's
strain relief, trimming if necessary. Tighten the 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. Silicone the socket's contacts.
If the socket assembly is internal to your model, replace
the strain relief on the body, then install the mounts of the assembly.
Attach the line cord to the socket with any sheathing and poke it out
through the strain relief. Mount the socket and restore the line cord
as above. Silicone the socket's contacts.
After doing the procedures in the "Electrical Tests" section,
set all aside until the remaining assembly work is completed.
- Additional Lubrication: Lubricate any hardware threads
that have not yet been done with a long-lasting, medium oil, and use
silicone spray for any lens guides, for or parts that slide past one another
such as shutters. Keep oil and silicone off any parts not intended. This
is especially true for the lenses, reflector, and lamp. Separate these
different lubricant types so that one type does not land on a part where
another is being used. One may compromise the operation of other.
A reminder to keep lubricants from landing onto your bench.
An oil/silicone soaked bench is not a good environment for lighting
fixtures because they will work their way into areas where not wanted.
Replace bench-top newspapers often.
- Final Assembly: Restore any remaining parts to their proper
location and orientation, lubricating as necessary. If the lens tube is not
yet installed, do this now. You may elect to leave the yoke and pipe clamp
off until after the alignment is done.
- Continuity Test: Use the `ohms' setting of your multimeter
to confirm a continuous electrical path from plug to socket. Check the
neutral path, as well. `Zero' ohms should be the reading. Diagnose and fix
- Shorts Test: Test for shorts between hot and neutral, and
from each conductor to the metal housing of the cap. If the meter reads
anything but "infinity", there are problems. Diagnose and fix before moving
- Lamp Test: You may choose at this point to install the
lamp as an additional test, but can wait if you must return to previous
sections to do more work. Do a lamp continuity test if you choose to
install it. If all is well, move on to the alignment.
This is best done with a stand or cradle which will support the
ellipsoidal with its shutters open. It may be made of wood or metal but
should have the supporting parts lined with cloth, rubber, or carpet to
prevent scratching the fixture body. Alternatively, one can use a pipe on
to which to clamp the light. Also, a screen or flat white wall is best for
proper alignment. A bonus is if the screen or wall can have a center dot
and concentric circles at half-metre intervals.
- Install the Lamp: If not already done, apply silicone to
the socket's contacts. This will facilitate later lamp removal in that it
will prevent the lamp from seizing in the socket. Unless using a new lamp,
do a continuity test on the old one. If it's working, wipe the bulb with
soft tissue dipped in methanol alcohol to remove dirt and finger oils.
Insert a working lamp into its socket. Close the lamp access door or
restore the cap to the lamphouse.
- Support the Fixture: Begin by setting the light in the
alignment cradle so that it is level and the center of the lens 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 circle. Lowering
the voltage is done to lessen the chance of lamp burnout during possible
rough movement as its alignment is adjusted.
- Focus: Moving the lens tube, sharpen the edge of the image.
For variable-focus (zoom) fixtures, set the image diameter to a middle size,
or if the fixture's location and use are known, to a size that suits. This
will matter less with top quality units as they exhibit the same
characteristics regardless of zoom setting. However, some cheaper units may
vary, hence this suggestion.
- Adjustments: Exact alignment procedures cannot be given
because they differ from manufacturer to manufacturer and sometimes from
model to model. However, via either set bolts or a single-control alignment
adjuster, move the lamp in and out of the reflector to achieve the brightest
circle on the screen. Some models will require that you reopen an access
door or remove a hatch cover in order to make this adjustment.
You may do a preliminary test on some models by not securing
the lamp and electrical assembly in its housing. Instead, carefully move it
by hand in and out of the lamphouse while tilting it back & forth and
up & down. When you see the desired brightness and degree of evenness
on your alignment screen, note the position and angle of the assembly in
your hand. This will give you a rough idea of where the alignment mechanism
must be set.
The hand method is less likely to be needed in modern fixtures,
but for older ones, especially those with three-bolt alignment setups, it can
speed the procedure. Reseat the assembly and adjust it to that point; test
by moving it around by hand until it's the way you want, and continue with
adjustments to achieve the correct point.
- Setting the Field: Now do a fine adjustment to achieve a
flat or peak field, and if peak field is chosen, where that peak occurs.
This means the fixture will either produce an even (flat) illumination
within its circle of light, or it will have a hot spot (peak) somewhere. An
off-center peak spot is achieved by sideways or up & down movement of
the alignment adjuster(s). You will see the bright area move around within
the circle. For theater stage washes, this hot spot occurs in the center.
For key light purposes, it often is near the top of the beam to throw more
light onto a person's head area or face. If unsure, go with a flat field.
- Verifying Your Work: Observe your final alignment with
the dimmer at the full-rated voltage of the fixture's lamp. Although not
necessary, one could use the `AC Volts' setting of the meter to ensure this
voltage is accurate. Operate the zoom optics through their full range to
see if the flat or peak field characteristics change. Re-adjust alignment
until you are satisfied it will work for your purposes.
Once done, fully secure the assembly in the lamphouse. Close
any access door or replace/secure access panels and you are done.
- 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.
Make a date tag by using white electrical tape which will be
placed onto the inside of the yoke. Make the date tag twice the required
length so that at the next lamp replacement, there will be room to write
the new date. This way, the date tag only need be replaced every second
If a new lamp is installed, mark the current year (four
digits) and month (two digits or three letters) on the tape. Should
the old lamp be used and its installation date is unknown, write the
current year and month along with `P.I.S.' This stands for "Previously
in Service". Otherwise, copy the date from the old tag, or reuse the old
tag if its condition is good.
Stick the tag 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
You should now have a refurbished
fixture that is ready to return
to your lighting inventory