Timeline for Do LEDs require more power to function as they age?
Current License: CC BY-SA 3.0
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| Sep 24, 2017 at 21:44 | comment | added | D.A.S. | I just read BenQ's service manual which uses PWM with 3.3V , so all the LEDS are in parallel, perhaps with 1 Ohm series R's ideally to compensate for ESR variations. If no series R then they must be matched for intensity and Vf for consistent brightness and hence no threshold effects. Thus the PWM can control brightness. But if the supply voltage drops from 3.3 to 2.8V then LED dropout may occur due to Shockley NTC effect and result on current sharing. So I would check BKLT 3.3V level for DC and AC ripple and check caps for bulging. The LED does not resemble the schematics shown here. | |
| Sep 24, 2017 at 19:30 | vote | accept | daedalus | ||
| Sep 24, 2017 at 19:30 | comment | added | daedalus | great answer, totally makes sense. As I recall my monitor a "benQ" was quite well priced at the time so would not be surprised if they cut corners. It's a shame monitors don't advertise this sort of info so I would know which ones to buy or avoid in the future. | |
| Sep 24, 2017 at 19:17 | history | edited | Michael Karas | CC BY-SA 3.0 |
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| Sep 24, 2017 at 19:08 | history | edited | Michael Karas | CC BY-SA 3.0 |
added 388 characters in body
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| Sep 24, 2017 at 19:02 | history | answered | Michael Karas | CC BY-SA 3.0 |