I have six identical 10 year old LED displays that have about 12 seven segment LEDs each. Recently I noted some of them have noticeably started to flicker and the flicker appears like a wave moving left to right. I do not have a schematic of the display circuit but since it is relatively new phenomena, and the fact the some still have absolutely no flicker, I am suspecting it is the result of a failed or failing component. If that is the case it would seem to me that the most likely candidate for a problem component that might produce flicker is an electrolytic capacitor that is no longer doing its job. Does this sound reasonable?

I have not pulled a cover as of yet, but electrolytic capacitors should be easy to identify and replace even without a schematic. If I am way off base then I won’t waste my time and perhaps someone could suggest another probable cause.

 

It sounds like it may a problem with the multiplex circuit and, yes, a failing electrolytic is a possible suspect.
It's going to be difficult to offer anything other than guesses without more information on these displays.

 

Thanks. Two opinions on a possible source of the problem is enough for me to continue on and at least give it a shot.

Thanks again.

 

The oscillator circuit that runs the display multiplexing may have failed and is running at a lower frequency than it should.

What is the source of the LED display drive? Knowing this will help identify the problem better.

 

Definitely, without additional information a completely accurate evaluation is not possible. However, if the displays appear to function the same , as an update arrives, meaning that the update scrolls across at the same rate, then it is most probably a power supply issue. Loss of capacitance in the supply output would allow the voltage to droop during the on time, showing up as a flicker. But a lower supply voltage would also produce similar results. Thus some voltmeter analysis is indicated. If an oscilloscope is handy then watching the voltage on the supply capacitor would also be very useful. But here is one additional thought: If the power supplies have switchable input voltage ranges, a similar symptom would arise if the selected input setting was for the high range and the actual input was in the lower range. Not knowing the context of usage, that may, or not, be another possibility, easier to fix but more subtle to find.

Please let us know when the actual cause becomes known.

 

It turns out it was an electrolytic capacitor in the transformer based power supply that was creating the problem. Thanks for all your suggestions.