The symptoms, the possible cause

Here is a list of probable problems and how to proceed

If possible and practical i start by checking the sign at night to see what the sign does , if it’s flickering , one side dark ,the middle dark, it’s completely dark, etc . by looking at the sign i can tell if it’s neon or LED , and what type of transformer it has , and 80% of the time i know what’s wrong with it . Like i said if it’s possible i start by doing the night evaluation , if not then i start by asking the owner what he saw , what’s wrong with the sign , most of the time they tell me what i want to know . Then i know where to begin.

  1.  The sign is flickering and only one side of the sign  is dimly lit and the other is completely dark.
    First, if it’s flickering it means it has an old type transformer with no GFI , so there are two main possibilities here ,
    One is that one side of the transformer went dead ,and the other is that there is a short on the transformer GTO  wire leading to the last letter of the circuit.
  2. The sign is flickering on both sides but totally dark in the middle
    this one is an easy fix , you go for the neon letter where the dark spot is , there may be one or two bad sections in the middle of the sign, you will have to replace them with new ones.
  3. The sign is completely dark no signs of life at all
    First check if there is a timer , if there is one make sure the small screws that turn ON and turn OFF  the sign are properly fastened , and check if the timer is on or off, if off turn it on , sometimes that is all the problem.
    If the sign still does not light up then there is a possibility it has a GFI transformer and it tripped because of a short , you will have to go to the transformer to check the transformer , check first the input (120 vac) and then check the output .
    If everything is good then you may have a short on both output GTO wires going to the sign , you may have to replace the GTO wire .
  4. It’s been raining a lot and you get a call the next day when  it stops raining because a sign is not lighting up
    You tell your customer that you will be there to check the sign in about 2 days , considering it will not rain again . The reason for the two days is to let the sign dry out , because it is very possible that it has a GFI transformer and there  was a temporary short  caused by the rain but once the rain stops there is no short anymore , so you just reset the transformer and the sign lights up again .
    You have to check the first and last letters to see if there are wires to close to the metal that could be the cause of the short, most of the time you can see a little spark residual where the short happened.Most of the time the shorts happen on the GTO wires coming from the transformer and going  to the first letter and the last letters on the that  circuit in a sign .Shorts  also happen when a neon letter dies of natural causes (Old age) and the electricity starts to look for the nearest ground and starts to ground itself to the metal part of the letter.
  5. If you want to test a suspicious Neon letter or section to see if it’s the one to blame for the sign not working correctly , you use a jumper wire and connect it to the two electrodes on the letter and then turn on the sign , if it’s a bad neon then the rest of the sign will light up .
  6. The finger test
    If you touch the neon glass and run it down the glass and you feel a tingling sensation that means the neon is good , a bad neon will not conduct electricity and you will not feel ant tingling sensation on your fingers
  7. Most of the time you have to use all your senses while checking a sign.
    The smell of burning tar is indicative of a bad transformer
    The smell of burned rubber is indicative of  either electrode boots burned or GTO wire burned.

Symptom - cause

So when possible check the sign at night , because it will tell you what to do the next day when you go fix the sign.It really saves you a lot of time

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