22me402v led tv strobe light effect

[freakaftr8]

Hey all well I just replaced the defective power supply in this funai made 22 inch led tv.I would have just repaired the power supply but it blew some components out on the hot side and finding all these components would exceed what they use power supply would cost on eBay. So anyways now that I put it back together what is going on is it seems there is a strobe light effect on LED backlighting its really consistent Flickr and it's super fast in you can hear the power supply ticking as the strobing is going on. I pulled the panel apart and every single LED is lighting up so it doesn't seem like its a burned-out LED. Has anyone run into this before on a backlit LED edge lit TV yet?

[freakaftr8]

Re: 22me402v led tv strobe light effect

Does anyone know around what voltage these leds are supposed to operate at?.

[tom66]

Re: 22me402v led tv strobe light effect

For a 22inch if it has a single strip of LEDs around 40 to 50V.
Check the voltage across the 200/400/450V capacitor.

[freakaftr8]

Re: 22me402v led tv strobe light effect

Thanks Tom. Yes im getting 41v from ground to the middle pin. There's 5 pins total. Middle.pin seems to carry the voltage.
And yes one light strip.

[freakaftr8]

Re: 22me402v led tv strobe light effect

Voltage across main cap is 165.4vdc. The main cap is a 200v 100mfd.
The 5 pins out to the led strip are
1. Led4
2. Led3
3. NC
4. V LED
5. NC
6. Led1
7. Led2

power supply model ba21n0f0102

[freakaftr8]

Re: 22me402v led tv strobe light effect

by the way I forgot to mention that the flickering effect on LED strip seems to be that of they are not lighting up to their full capacity so the screen is real dim when those LED's are flickering it's almost like they're loading down or something. Seeing them flicker is almost like looking into a strobe light. Thats how fast the flickering effect is.

[tom66]

Re: 22me402v led tv strobe light effect

Approx how many LEDs on each strip?

40V is only enough for about 10 to 12 white LEDs. I'm guessing it has around 40 to 50. The way these designs work is they put four parallel strips of series LEDs, one end attached to 40V and the other going to a constant current sink, that's the outputs LED1,2,3,4 which should measure near 0V. That way each chain of LEDs gets the same current. LEDs aren't perfect, their voltage drop and hence current through them varies, which means they can't be directly put in parallel.

What can happen is if the constant current sink can't regulate the current they will flicker.

Can you post some clear detailed photos of the power board? Top and bottom sides.

[freakaftr8]

Re: 22me402v led tv strobe light effect

[tom66]

Re: 22me402v led tv strobe light effect

See photo..

[freakaftr8]

Re: 22me402v led tv strobe light effect

Yes that is the connector. And the other part is the regulator? All pins led 1 thru 4 all registered around 0v

there are 34 leds on the strip.

[tom66]

Re: 22me402v led tv strobe light effect

Probably, can you get the part # of it?

[freakaftr8]

Re: 22me402v led tv strobe light effect

Really hard to read.
Ai
209pc

[tom66]

Re: 22me402v led tv strobe light effect

Try an angled light or using the macro mode on a camera.

[freakaftr8]

Re: 22me402v led tv strobe light effect

I guess what I'm getting at is there any chance the LED strip to be bad or is this bad power supply you think

what I see on the ic is all I can get

[tom66]

Re: 22me402v led tv strobe light effect

I think it's probably a bad power supply more than an LED problem.

[freakaftr8]

Re: 22me402v led tv strobe light effect

Ok. Thanks I'll talk to the people I got it from

[freakaftr8]

Re: 22me402v led tv strobe light effect

I just got to thinking about something. Whats the possibility that the mainboard is throwing it for a loop. In the bl_on or bl_dim? Ones at 2.9v and the other is at 3.3v when on. These voltages are taken off the ribbon connection between the mainboard and the power supply

[ecking767]

Re: 22me402v led tv strobe light effect

Really hard to read.
Ai
209pc

I have an Emerson LED with a similar board to your, I betting that chip is a HAI 7209 PC

[freakaftr8]

Re: 22me402v led tv strobe light effect

Yep thats it! Was that you're problem with yours?

[tom66]

Re: 22me402v led tv strobe light effect

Huh, can't find anything on that chip...