| Caution: High voltages, currents, and temperature are required to
operate lamps. Therefore, shock and burn hazards exist, and testing or evaluating fixtures
or components should be done only by qualified individuals.
A. Testing Lamps
The easiest method of troubleshooting a fixture is to try a
known good lamp in the inoperative fixture. If the lamp being replaced exhibits any
of the following conditions, replace with a new lamp.
1. Sodium Leaker Lamp - will have a brown/golden
coating on the inside of the lamp envelope other than at the base of the lamp.
2. Amalgam Leaker Lamp - the lamp envelope will have
a smoked bronze appearance on the inside of the envelope.
3. Faulty Base to Lamp Envelope Seal - a white
pow-dery substance will appear at the base of the lamp where oxygen has leaked inside the
lamp.
4. End of Lamp Life - the arc tube will be black on
both ends or the entire length of the arc tube will be black.
5. Broken Welds or Arc Tube Support Brackets - mechanical
breaks occasionally occur due to rough handling or internal thermal stresses. Broken welds
in evacuated (HPS) lamps can also create a problem known as vacuum switching. Extremely
high voltage surges occur in the lamp circuit if the weld opens while the lamp is
operating. Secondary coil burnout, ignitor arcing and socket arcing can occur. Rewelding
may occur and the lamp may appear to be satisfactory; however, if left in opera-tion,
failure of the ballast and/or ignitor is likely.
B. Ignitors/Starters
The starter provides the necessary voltage and energy
required to initiate the arc in the lamp. The easiest way to check the ignitor on 35W to
150W HPS units is to install a 120V incandescent lamp in the fixture. If the incandescent
lamp operates but a known good HPS lamp will not ignite, replace starter. In 200W to 1000W
HPS fixtures, install a mercury lamp of similar wattage. If the mercury lamp lights and
the HPS lamp will not, replace the starter.
Do not operate Incandescents or mercury lamps used to check
the starter for extended periods of time (more than ½ hour).
C. Capacitors
Testing Capacitors may be accomplished by:
1. Visual Inspection for swollen capacitors. If the
capacitor is swollen or bulged on the sides or top where the terminals are located, remove
and replace with a new one.
2. Verify the correct microfarad rating as specified
on the ballast I.D. label.
3. Using an ohmmeter to check capacitors: discharge
capacitor by shorting between the terminals disconnect capacitor from circuit remove bleed
resistor
1. Set ohmmeter to highest resistance scale and
con-nect leads to capacitor terminals.
- if resistance starts low and gradually increases, the
capacitor is good.
- if resistance starts low and doesn’t increase,
the capacitor is shorted and should be replaced.
- if resistance is high and remains relatively the
same, the capacitor is open and should be replaced.
D. Ballast
Visual inspection of the coil for burned or charred
windings is the easiest method for checking the ballast. If lamps, ignitors and capacitors
test good, replace the ballast. Testing the voltage at the socket is another method of
checking the ballast. However, to use this procedure you must know specific ballast/ lamp
voltage and amperage requirements. The starting aid (if present) should be disconnected
prior to testing the voltage at the socket. Failure to remove the starting aid could
damage the test equipment.
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