The following is a field proven troubleshooting routine which will allow you to locate and repair electric sign problems quickly, without expensive return trips.

Symptom: Repeated early lamp failure. Note: most H. O. fluorescent lamp manufacturers rate their lamps for 10,000 hour lamp life. In normal sign operation that should equal 18-24 months.

Repeated lamp failures in a sign most probably indicate that the problem is not with the lamps. To troubleshoot the sign properly, you will need:
(a) known good lamps
(b) known good ballasts
(c) a filament heating voltage tester
(d) a volt-ohm meter or voltmeter and pen type continuity tester with
pin-prick probe and alligator clip.

Step 1: Examine lamp ends looking for heavy, solid darkening approximately 2 to 4 inch long at one or both ends. This indicates the lack of proper filament heating voltage. Unless this condition is corrected, new lamps will fail in short order. Note that during normal fluorescent lamp operation, mercury may collect at one or both lamp ends which visually appears as a dark spot. Do not confuse this with the dark band described above.

Step 2: Be sure the sign cabinet is properly grounded. The easiest way to test this is to measure the voltage between the sign cabinet and the ballast white and black leads. There should be full voltage to the black primary lead of the ballast and no voltage to the white primary lead. If sign cabinet is not properly grounded, correct this condition before going
forward.

Step 3: Test the primary voltage at the sign. This should be between 110 V and 130 V. If this is not the case, determine cause and correct.

Step 4: Inspect ballasts for signs of leaking filling compound or wet ballasts in the bottom of sign cabinet. Replace any ballasts evidencing these conditions. Note: it is best not to mount ballasts in bottom of sign cabinets to avoid water related problems.

Step 5: Check ballast wiring to ensure it matches manufacturers specified wiring diagram. There should be no unconnected or "snipped off" leads.

Step 6: Inspect all lampholders for broken or corroded contacts or presence of moisture, dirt, bugs, or other contaminants in the lampholder. Clean or replace any lampholders with these problems.

Step 7: With filament voltage tester check each lampholder for proper voltage. With power on, the tester bulb should burn bright at each lampholder. If the tester does not burn brightly or does not light at all, locate the ballast leads to the lampholder. Disconnect the power. Cut and strip the leads near the ballast. Turn on the power and touch the stripped leads directly to the filament voltage tester. If the tester does not light, replace the ballast as it is not generating adequate voltage to properly operate lamps. If the tester does light, there is a "short" in the wiring from the ballast to the lampholder which must be identified and repaired.

Step 8: If the filament voltage tester burns brightly in all lampholders and known good lamps won't light, shut off the power and disconnect ballast primary leads. Check all ballast secondary leads with continuity tester for "short" to ground condition. If continuity tester indicates a "short" condition, disconnect power. Cut and strip leads near each ballast, and test with volt-ohm meter or pin-prick probe. If "short" exists, establish whether the ground is in the ballast or in the sign wiring. Either replace ballast or correct wiring problem.

By following this troubleshooting routine you will determine the cause of the fluorescent illuminated sign problem in one trip, reducing the cost of servicing signs and keeping your customers happy.

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