Star Tech Journal

Issue: 1989-March - Vol 11 Issue 1

Marquees and Ceilings
bend and make their contacts touch together. When
these contacts touch, the neon gas stops glowing
because current is flowing through the glow switch,
the fluorescent tube, and the ballast. At this instant,
it is exactly like having someone push a start button.
The filaments in the fluorescent tube glow and pre-
pare it to fire. With the neon extinguished, the heat
source in the glow switch is removed, and the bime-
tallic strips cool off enough to break the contacts and
bend back to their original separate position. When
the glow switch contacts break, the ballast trans-
former provides its inductive "kick," and the fluores-
cent tube turns on.
- - - - - - --
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Figure2
Starter: Inside And Out
The starter as a whole is connected in parallel with
the tube, but when the tube is lit there is not enough
voltage to relight the neon gas in the glow switch. So
the contacts stay apart.
Remember the capacitor? It absorbs the arc formed
when the contacts open, so it makes them last longer.
It also reduces radio interference caused by the arc.
If the metal contacts in the starter weld together, or
the capacitor shorts out, current would constantly
flow through the tube filaments, quickly burning
them out. This ruins both the starter and the bulb, so
you'll have to replace them both. Something else to
worry about.
INTERESTING ASIDES
~- An interesting thing about fluorescent bulbs is the
• gas in them will not fire at low temperatures. Once the
bulb is started, however, it will stay lit regardless of
how cold it is. That's why they come on fine early in
the day when the heating system is on, but if the tem-
perature drops in the afternoon to around 50 degrees
F, they won't work if someone shuts them off and tries
to restart them again. A good rule of thumb is if it's too
cold for you in shirt-sleeves, it's too cold for fluores-
cent bulbs.
A fluorescent bulb will glow all by itself, with nothing
connected to it, when hit with strong radio-frequency
(RF) energy. There have been several cases of people
who live near powerful transmitters reporting that
they can't shut off their lights! Aerospace companies
sometimes test certain radio dishes by holding fluo-
rescent tubes in the beam paths. High-voltage power
lines can light them on the ground.
WHAT CAN GO WRONG AND HOW TO FIX IT
The most common failure is a bad bulb, and substi-
tution is the only cure for that. After removing a
suspect bulb, lift one end of it and then the other, and
listen for rattling sounds. Does it sound like some-
thing is rolling around inside the tube? If so, one of
the filaments has broken loose. A tube will not light
if a filament is open, so check for continuity with a
meter on both ends. Sometimes, though, both fila-
ments may be good and the tube will still be bad; the
vacuum seal may be punctured, or the bulb has just
reached the end of its life.
If a tube is black on both ends, the tube is darn close
to dying on you. Each time the lamp is started, the
filaments glow and burn off some of the phosphors
close to them. Over time there won't be very many
phosphors left and this lets you know that the bulb's
age is showing.
READY SET START!
If the bulb won't light at all and bulb subing doesn't
work, you may have a bad starter or a bad ballast
transformer. The starter has two ridged legs under it,
and a light counter-clockwise twist will remove it from
its socket. If a new starter doesn't do the trick, pray
for a loose bulb socket or a blown fuse. The ballast
transformer is just a coil of wire, so check for conti-
nuity; if it has a burning smell and/ or still doesn't
light the tube, replace the ballast. It could have a
shorted turn in it, and not many of us have a coil
tester. You can quickly check for proper voltage by
removing the starter and sticking the meter probes
into its socket. If you don't get 120 Vac you know
something's wrong.
Continued on next page ...
Servicing Fluorescent Lights (Continued)
DOES IT SING?
Is the fixture humming like crazy? Check the ballast
transformer. Its laminations have worked loose and
the energy inside is making the sheets of metal move
120 times a second. Does the ballast have bolts
running through it? Tighten them. This pushes the
laminations closer together and keeps everything
quiet. If the ballast is a sealed unit, replace it if people
complain (if you're around it all the time, you forget
about it completely unless someone from the outside
says, "Doesn't that humming drive you crazy?").
DIMWIT
If the bulb always flickers dimly and doesn't ignite,
chances are it's the bulb. If replacing it doesn't help,
try a new starter: they're cheap. A brand new bulb,
once installed, may take a few moments to get used
to its new home by flickering and restarting. It should
work fine after a minute or so. If the new bulb never
stays on, try a new starter.
(and leave your business open for a lawsuit). Toss it
in the parking lot dumpster or tie it up securely for the
garbage, with a note for the garbagemen explaining
that they are handling glass.
PARTS TO STOCK
Almost from day one, Atari uses a 15 watt, 18 inch
bulb. Same for Sega and Bally/Midway. For games
like Joust and Robotran, Williams used a 14 watt, 15
inch tube. All of these use the same type of starter,
one rated for 10-20 watts. (By the way, don't let
anyone try to sell you 30-40 watt starters for video
game fixtures because they just don't work.)
ll.O VA'-
VISUAL TESTS
A trick: starters have a small hole in the tops of their
cans. If you can see this hole when everything is
installed, check for flashes of orange or purple light
coming from the bulb inside the starter. If you see the
light, the starter is good: if there is no light, the starter
is bad or a tube filament is open.
Does the bulb come on fully, shut off, and repeat this
on-off cycle? The bulb is bad: the gas in the bulb is
getting weak and lacks the strength to stay on. Does
the bulb stay dark, but the ends remain lighted? The
starter has shorted. That means the bulb has a
massive amount of current running through it, dras-
tically shortening the life of the filaments. Replace the
starter and the tube.
DISPOSAL
At least half the time, your fluorescent light fixture
problems come from bad bulbs. Be extremely careful
when throwing them away, since they contain a
vacuum and will implode if dropped: they are stlll
made of thin glass, remember. Keep people away from
you when working with bulbs. Then, if you drop one,
RUN LIKE HELLI Not only can the glass shards fly into
youreyeballs,butthephosphorusdustwilltearyour
lungs to shreds! If a tube breaks, DON'T BREATI:I
TI:IE FUMES! If a glass shard cuts into you, even a
small cut, get it treated yesterday! Beryllium and
mercury are poisonous.
Never just leave a bad tube intact in a garbage can
where someone can accidentally get his hands on it
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Figure 3
Automatic Starter Schematic
GAME TIPS
Can't fmd the starter in an old Bally game? It's behind
the fixture. If your hand can't fit back there, a
quarter-inch nut driver will easily remove the fixture
so you can get at the starter. By the way - some Bally
games have the weird Bristol-head screw with the
center pin to hold the marquee bracket. A Sega
Outrun wrench fits these perfectly. Sega's Za.xxonmay
give you a headache because its starter is completely
enclosed inside the fixture case. Not only do you have
to take the whole thing apart to get to it, but you may
not recognize it at first because the starter has no
outer casing. It is just a glow switch and capacitor
spliced into the wiring. If possible, replace it with a
socket so future techs can remove starters more
easily. There may be more ·Sega games with this
peculiar setup.
BOTTOM LINE
Got it working? Good! Players are very much im-
pressed with a game whose marquee works, no
matter how old it is. Now they can find it, too, since
the ceiling lights work again. Sit back have a Coke:
you deserve it!
~

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