111
TROUBLESHOOTING FLUORESCENT LIGHTING CIRCUITS
Electromagnetic Rapid Start, Instant Start Electronic, and Preheat
Fluorescent Light Circuits
WA R N I N G :
A qualified service technician must be used to preform these tests using extreme care
because of the risk of electrocution if tests are not preformed corre c t l y.
There are different types of lighting systems being used in True cabinets, so there will be different types of
troubleshooting techniques that need to be used. The one common aspect in all of the lighting circuits is that
the bulbs being used must be the same as the bulbs that were originally installed in the cabinet.
To test ballast determine which lighting system you are working on and follow steps below.
Electromagnetic rapid start fluorescent light circuit – There are three different voltage tests.
Incoming or ballast supply voltage- Test at black and white wires going to ballast. You should read
approximately 118 volts.
Filament voltage- Tested between red to red wires or blue to blue wires. Depending on which ballast you
have you should get a reading between 2 and 5 volts with the bulbs out. Please call technical service with the
ballast number to get the correct voltage reading.
High voltage- Test between either red wire and either blue wire. Again depending on which ballast you are
checking the voltage can range between 205 and 310 volts with the bulbs out. Please call technical service
with the ballast number for the correct voltage reading.
Instant start electronic fluorescent light circuit - (Note: A high impedance meter is required for testing
this ballast.). There are two different voltages to test.
Incoming or ballast supply voltage - Test at the black and white wires going to the ballast. You should read
approximately 118 volts.
High voltage - Test between the red wires and anyone of the blue wires with the bulbs out. You should read
approximately 600 volts (+ or - 10%).
Preheat fluorescent light circuit – Test voltage between pins on each end of the lamp. You should get
approximately 118 volts from one pin on one end to one pin on the other. You can also check for continuity
between the other pins on either end to the starter base. (To do this test make sure there is no voltage to the
circuit and remove the starter from the base.) If both are ok change the bulb first and then change the starter.
FOR ANY INFORMATION OR HELP DIAGNOSING BALLAST PROBLEMS PLEASE CALL.
TRUE MANUFACTURING TECHNICAL SERVICE
1-800-325-6152
Revised 9-24-02 SB
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