Suggestions Please

[rfsign]

I am working on a sign that reads "National'. It is white neon(argon and mercury). The letters are all on one transformer. The letters N & a are either very dim or not illuminating, the rest are illuminating. I checked the tubes with a tester and they appear to be good (they blink). Because they are white it has been very hard for me to see if they are illuminating when I remove the covers and turn the sign on during the day but at night with the covers on they do not appear to be giving off noticeable light. They are back lit channel letters so I can see the light on the wall from the other letters. What I have done so far is clean up the GTO wire connections between the letters to see if I was losing power because of bugs and/or corrosion but this did not work. My other inclination is to replace the two letters. The electrodes are really black on both of them so my thinking is that there just isn't enough gas in the tubes to illuminate but enough to carry the current to the other letters??? I want to make sure I am not missing something before I go and spend their money on the new letters. Any help is much appreciated.

 

[nodrenim]

Try removing the neon units in question and see if you can find the mercury in the unit. Move the mercury to the electrode nearest the dark area and hook it to a spare transformer for a few minutes to see if that solves your problem. I have done this several times on existing units with good results. Sorry I did not answer sooner on this, I've been busy lately, thank the lord for small favors. Peace,