Your Guide on how to use
Electronic Tranformers
Electronic transformers are NOT direct substitutes for magnetic transformers. While they have gotten much better since their introduc-
tion decades ago and we appreciate their lower cost, smaller proles and lighter weight, there are many situations where they will NOT
WORK. We have put this guide together to help you build successful installations and to let you know when an electronic transformer
has no chance of working. While these tips and tricks are not foolproof, they come from years of discussions on technical help calls.
Let’s start with an understanding of what these products were designed to do:
1. INDOOR ELECTRONIC TRANSFORMERS were made to replace magnetic transformers that hung on the back of beer signs.
The electronics were far lighter which helped shipping them from the manufacturer; they used less energy and cost less. They
were attached to a simple metal frame where there was usually plenty of clearance around the GTO. A hanging window sign on a
plastic back may have capacitance coupling issues that must be mitigated and aluminum clad plastic can be dicult to make work
successfully.
2. OUTDOOR ELECTRONIC TRANSFORMERS were made to replace PBKM style transformers in channel letters – that’s what
CL stands for in the model designation. In a pure form of a channel letter, the PBKM sits in the back of the cabinet with the neon;
there is no GTO; almost always there is only one transformer per letter. And most importantly, at no time does the energy from the
transformer pass through the back of the sign, or a raceway, or a cabinet – that is, no energy from the transformer passes through
anything that it can capacitance couple with. Whenever energy from the transformer passes through a surface (sign back, raceway,
whatever) – whether that is through the GTO, a housing, or the tube itself, it wants to capacitance couple; the more times it passes
through the more opportunities it has to capacitance couple. The tighter the space between the GTO and whatever it is passing
through, the greater the capacitance coupling. Keeping this in mind and thinking about how far you are straying from the original
electronic transformer design intention will give you an idea of the likelihood of the sign working trouble-free.
General information for what NEVER to do with electronic transformers:
• Do NOT cut the cord o of an indoor transformer – it violates UL and voids the warranty.
• Dimming in the center of a set of tubes is NOT overloading, but is energy not going through the tubes (nding the path of least
resistance through capacitance coupling). Overloading the transformer causes it to ash 3 times and shut o. The solution for
dimming in the middle is often through spacing of GTO and/or tubes. Sometimes it cannot be overcome – you should be using a
magnetic transformer.
• Pay attention to the distance between the GTO wires where it exits the transformer body - you should NEVER let the GTO run
parallel to each other closer than this built-in gauge.
• Avoid running GTO parallel to itself and NEVER run GTO parallel between two dierent transformers.
• While equal lengths of GTO are preferable, do NOT keep excess GTO on one side just to make them the same length – cut it o;
shorter is always better.
• When GTO must cross, do so at right angles and not parallel.
• Three ashes of the transformer indicate either: a) open circuit / dead tube; b) overload of transformer. Test for dead tubes by
process of elimination by rewiring the sign (jumping some sections out) to see if half the tubes light with the transformer and then
rewire and see if the other half of the sign will light. If half the sign lights and the other side ashes 3 times, continue process of
elimination until bad tube is found. If all tubes light on each half of the sign, then it is most likely overloaded.
• There are two ways manufacturers of electronic transformers rate their transformers: 1.) like Ventex does with a name that emu-
lates the footage and performance of the same voltage magnetic transformer and 2.) the actual voltage output. When replacing
a “6kV electronic transformer” it may mean you have a transformer that emulates a magnetic 6kV but actually puts out 3kV or
the “6kV transformer” may be an actual 6kV output which runs the same footage as a 12kV magnetic. So, when replacing these
transformers from one brand to another, be sure to compare the primary amp draw to make sure they are similar in order to get the
same performance for the footage they each run.
• Ventex CL Series transformers are rated for “outdoor” but that does not mean they are waterproof.
