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.