[Boatanchors] Your experience with China made freq counters

[Tom Norris]

Yes, the LCD display's seals *can* fail over time, but it's a crap shoot as to whether they actually *will* fail.  When they do, the lcd "gel" inside can be exposed to air and the display will slowly stop working - or suddenly stop, leaving a big black blotch, depends on the mfg design of the particular display.

The only display I can think of that has a specified limited lifespan are incandescent-segment "numitron" displays. They were popular in the 70's and still made. A very common use was in the readout of fuel pumps until LCD displays were developed that were resistant to wider temperature extremes.  It takes many years of 24/7 service for them to fail in this way.  Even nixes and flat plasma multi-segment digits can fail.  Like any tube, air can leak in through the pin seals slowly until one day the tube just won't glow.  "Numitron" incandescent displays can fail via bad vacuum seal, but this is more rare than simply "burning out" (like a light bulb) or dying due to filament breakage caused mechanical shock, as the segments are simple incandescent filaments.

LED displays can indeed fail, though modern LEDs (Mid-1970's and later) fail very rarely.  Most modern LED devices I've seen/repaired have had faults in the digit/segment driver circuitry rather than the display module itself.

Tom  NU4G


On Jul 28, 2010, at 5:29 PM, mac wrote:

> Do I recall something about liquid crystal displays having a finite  
> life span?
> 
> Dennis D. W7QHO
> Glendale, CA
> 
> *********
> On Jul 28, 2010, at 3:22 PM, J. Forster wrote:
> 
>> LEDs don't have any limited lifetime AFAIK. They do sometimes fail,  
>> like
>> any electronic part, but do not "wear out"