Saturday, November 30, 2013

How to trouble shoot a LED kit? (and Quick fix)

Every kit we shipped had gone though a 10 hours burn in test, however the kit may still got damaged during shipping or by installer.  And these LED chips can be damaged by ESD (Electrical Static Discharge) before they are installed and grounded. ESD can be introduced as easy as one finger touch and a lot depends on what the installer wear (like sweater and shoes). The movement of human body and cloth can generate static charge and it may build up, and we would like to release that charge before we touch LED module. One common practice is to release charge from installer prior to touch sensitive electronic parts. Such as touch grounded environment object with bare hand or body part.

But damage may have been already done, So we need your help to determine where had gone wrong.
First, you should describe what model is your kit and what's the problem. Tell us how many LED modules are linked together. Then we need you to identify the model number of your LED driver, like shown in below picture, the model number is LPC-60-1400.

Then with the wires correct connected and tucked away, we want to do a live test with power turn on.
Our test should avoid any AC part and only perform on our LED module. If you have a voltage meter like multimeter, use it to measure driver output, read the voltage (LPC-60-1400 should output 42V)
But most of us don't have a meter, we can test it one by one by using a metal tool to short the two solder points of the LED module. Be aware, when you short circuit one module, the rest of modules may come up in full brightness, so be prepared for that. When a bad module is short circuits, all good modules will come up in full brightness. A quick fix is to connect the two wires of the bad board and rest of modules will continue to work. That's if you know how to do wire splicing. 

Fig: use a metal tool to short circuit a module

These points only has DC power supply to, it's safe to touch with hand..

Thursday, November 28, 2013

Kits safety

Below picture shows our driver and module work under water, Of course, that's not recommended. Our LED driver is rated IP67, which means it can work under water less than 1 meter deep.
The output of LED driver output is less than 24V DC, which is not hazard. The real dangerous part is the AC wires, just need to protect the AC wire and plug from water.
To place our lamp at damp places, there shouldn't be any problem.

LED kit burn-in process

Have you seen new installed LED street light just went dark after a few day? Have you seen LED traffic light got broken just after a short period of time? Isn't LED lighting suppose to long life? Why do we see so many failure LED around us?
After our study, we find out this is a popular problem among high power LED; less with lower power LED. One of common reason is bonding wire broken.
What's bonding wire? It's a thin wire that connects silicon die and Chip package connector. With high power LED, its chip die can go up and down in a wide temperature range; and due to material can contract and expend at different temperatures, this bonding wire may broke if the die, bonding proxy and connection pad are in an odd arranged position.
Does LED manufacture test their product? Yes, they do, to an extend. their expensive tester machine can make contact to chip connectors without making a solder point. However, they won't occupy expensive tester machine with low price (few dollars) chip for a prolonged time.
So this has to come down to us.
Modules from Easy LED Lighting are basically tested by China manufacture, so they do work. But after we were into this business a while, we found out there are a low percentage of modules would fail after just a few days of usage; otherwise, they would work for a long long time.

Right now, we burn in test our kits products, every kit will gone through a 10 hours burn-in process with on/off sessions control by timer, just to ensure their quality.