6V or 3V LED??

[jason123]

So, I have always used 3V 1W 3535 LEDs for backlight replacement. I have both the small pad anode and small pad cathode type.

Just opened up a Vizio that uses the same size LED, but measuring the good ones, seems they're 6V, by then I had already replaced all 8 bad LEDs with 3V. Is that a problem?

Yes, If the logic board is looking at "hard coded" voltage differential, the backlight might not turn on.

Yes, if the current is controlled using the "hard coded" / expected voltages assuming 6V drop, then it's a problem.

But.. don't these TVs drive current based on measurement across known precision sense resistor?? So if it lights up, should be oK??
Curious to get experts thoughts.
Thanks

[neilc6]

Re: 6V or 3V LED??

For models that have protection shutdown due to shorted LEDs, the voltage needs to be correct (LG, RCA, Insignia). Samsung designs dont have shutdown and you end up with most LEDs shorted and possibly power supply damage. Havent done enough Vizios but the one I did do had local dimming so each strip was independently controlled. The only other Vizio I replaced had the backlights turn blue.

[dick_barton]

Re: 6V or 3V LED??

I'm not certain I have this right but here are my thoughts.

If a led strip fitted with 6V leds have 3V leds inserted, then the voltage drop across the strip will be lower by 3V for every 3V led used on that strip.

Assuming that the 3V led can take the led strip current, let's say 150 - 200mA then the only thing that happens is the led strip voltage will be lower by 3V x number of 3V leds fitted to the strip.

The led driver IC generally has an over-voltage and under-voltage input so if the voltage across the led strip drops sufficiently it could turn the led driver off.

[jason123]

Re: 6V or 3V LED??

Thank you.. agree with all