I recieved a service call on a set of LED channel letters. The customer stated  that the letters are not illuminating bright enough at night. The letters are driven by (1) Advance 12V transformer. All of the LED's are lighting consistantly dim. The voltage output under load is 11.9V.  I removed the load from the transformer except (1) letter, the intensity did not change.  The transformer temperature (by touch) is hot.  The letters burn 24/7.  The LED's are in a plastic block (4) LED's per cluster, aprox 22 clusters per letter with (6) letters. The Advance transformer is a LED120A0012V50F.

This is a new customer, the sign is only a year old, but the company they purchased it from is out of business.  The sign is 50+ miles from my shop. I do not currently inventory LED components. 

The supply voltage is correct 113V.

Is the transformer likely defective even though it is producing the correct voltage while under a load?

How do you correctly load a LED transformer?

It has a 60W or 5A output. Do you use a amp guage to load it?

What percentage of the 5A output can be loaded?

I need to complete this job corrrectly and as soon as possible.

Can someone please give me a quick 101 on trouble shooting LED.

Thank you.