Help with Low Hours Preamp LED Failures

avanti1960

avanti1960

Well-Known Member
Hello,
The LEDs for my preamp meters (Cary Audio SLP-05) fail about every year or so. I run my system 50 hrs a week but I thought LEDs should last longer than that.
Every time they fail I have to order a $50 light assembly and the unit has two meters.

Can anyone help me source longer life LEDs that I can sub for the ones on this assembly?
Thanks.
Tony

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IMO, there is no way it should burn through the life of a properly operated LED in one year, is it VERY bright?. If I had to guess, the peak reverse voltage of the led is being exceeded causing an early death. Adding your own diode and capacitor to feed only DC to the LEDs should fix the issue. You should get 1000s of hours out of them for sure.
 
If fed by AC, I usually add a single diode and a capacitor to convert the AC to DC, and then calculate a resistor to run the LED on the safe side, something around 10 to 15mA.

A schematic of the unit and the Led wiring can help to tell you exactly what to do. (Or, measure the voltage at the Led terminals to see if Dc or Ac and the actual voltage feeding the leds)

But IMHO the problem is the power supply to the leds, not the led lifespan.

And for sure you can replace 4 led with less than $100 !!!!!!!!
 
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Yes, it would be easy enough to just replace the LED's in the existing light bars.
And a whole lot cheaper. You cod get a hand full of LED's pretty cheap.
But ad already suggested several times, add a diode.
 
If they are in fact being fed DC, have a look at the series drop resistor to see if it makes sense. LEDs are more of a current-limit device and running them with too much current cooks them.

and +1 on just re-lamping them. they look like standard through-hole type LED. If you've ever had desire for a different color, now is your chance to get it.
 
BMW charges 121 bucks for the light bar for the 80s On Board Computer. These used to be about 35. I have been swapping out the burned out light bulbs for LEDs for years. I even found a BMW dash colored LED to use in them. Just use the right dropping resistor and wire the LEDs in series and the light bar is good to go for years.

Your light bars don't look much different.

I'd get some measurements and look for some LEDs on Mouser/Digikey that will work and order some. Do you have the old light bars available to work on?
 
Thanks to all responses. The unit is at Cary for service, they believe AC is getting to the LEDs because they have a high frequency flicker before they eventually fail.
 
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