If the neon is OUT and the primary power is ON when you arrive on-site, do not turn the primary power OFF until you look at the diagnostic LED on the end of the transformer. This is important since the fault that originally caused the sign outage may have disappeared, but the transformer tripped OFF before the fault cleared (a “transient” ground fault).
Before working on the sign check if it is ON, OUT, or flickering.
Never change or repair any transformer wiring without first removing primary power from the transforme
Tubing OUT, LED 4-pulsing
Primary voltage is greater than 140 volts for a 120 VAC transformer, or greater that 324 VAC for a 277 volt transformer. A 120 VAC
transformer might be installed on a 240 or 277 volt circuit or the line voltage may need to be lowered by the electric company.
Tubing OUT, LED 2-pulsing or 3-pulsing
Always caused by one of two situations:
a. A short from sign GTO or tubing to the sign frame, conduit, or other point at or near ground potential (a “secondary circuit ground
fault”). This fault may be “transient.” (See introductory paragraph this page)
b. Line (“hot”) and neutral wires are reversed (i.e. polarity is reversed).
To find the fault:
• Remove and then reapply transformer primary power.
If the tubing now lights normally and the LED is continuously ON, a transient ground fault has occurred. This is usually caused
by build up of insects, a rain downpour, inadequate clearance between high voltage connections and the sign body, and so
forth. Check the sign for any of these conditions. Poor or non-existent primary grounding makes ground fault detection far
more likely to occur. If the LED was originally 3-pulsing the transformer is poorly grounded – make sure you have a good
ground connection. If the LED continues to 2- or 3-pulse go to the next step.
• Remove primary power and disconnect both GTO cables from the transformer. Reapply primary power. What is the LED
indication?
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