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Electroluminescent Panel (EL) - short life

I have a situation where I am on my third replacement of a Levitton model 6124H timer because of the failure of the blue Electroluminescent backlight failing leaving the LCD panel difficult to read. Otherwise the unit has no other failures and switches its internal relay and external fan load reliably.

So far Levitton has been good, providing me a second unit under warranty. The QC department claims that pressure from the decorative (DECORA) trim is causing the panel to fail. I have this unit installed in a garage wall (backing an interior wall) inside a three gang box. The humidity in the garage is controlled by a small AC unit, and does climb a bit. Temperature is well within range.

Any thoughts?

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo  ;-P
Reply to
RFI-EMI-GUY
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Humidity seems to kill ELs, gradually. They also fade with time on their own. LEDs are the way to go.

Do they fail suddenly?

John

Reply to
John Larkin

humidity and excess drive level kill ELs.

Steve

Reply to
osr

Electroluminescent devices normally degrade. The usual ones are essentially capacitors where the dielectric is lossy and has some sort of phosphor or phosphor-like material that converts some of the dielectric loss to light.

I don't have hard figures handy as for how fast 120V 60 Hz ones typically degrade, but I am under the impression that half-life uis a few years.

In my past experience, I have also had one electroluminescent nightlight develop dark spots in a couple years (IIRC) and completely fail within a year or two after that. I do not know why that failure occurred.

What I consider a nice thought: 470K resistor, bridge rectifier, and a Nichia NSPG520AS green LED. My experience with that one is efficiency unusually high for InGaN green LEDs, and unusually good at very low currents.

(I had to buy 100, and Nichia generally only sells from their sales offices and to end users and OEMs, requiring purchasers to not resell them. Fortunately, I had a few projects using these, some using more than one.)

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

I've been told that dark spots are due to moisture absorption: I had a few EL nightlights that developed dark spots and died; the manufacturer said the revised design had better hermetic sealing and, indeed, they lasted for many years without any dark spots developing.

---Joel

Reply to
Joel Koltner

I called Levitton and their first comment was that the trim panel is pressing on the EL panel causing the black spots. With their suggestion I removed the trim and the panel came back to life. I reinstalled the trim and left the screws loose and it died entirely. I then installed the warranty replacement, with the trim panel and loose screws and it failed entirely within a month. I am in Orlando area so humidity is a problem (which is why I have a small window AC unit in the garage. Levitton has send a second replacement which appears to be holding up (day 2). I think they know these are problematic. However the unit gets good reviews on Smarthome. I have EL nightlights that lasted 5 years or so. This unit lasted less than a year and its EL panel is only lit when making a button selection.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo  ;-P
Reply to
RFI-EMI-GUY

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