Samsung UN32F5500 smart TV no backlight

[thelmores]

Re: Samsung UN32F5500 smart TV no backlight

This thread is about 1.5 years old, but I appreciate the information. I have bought some replacement LEDS, and am going to try and repair 3 bad strips out of 5.

From what I can see in this case, the LEDS short, not open. Each strip I tested would light up, except for 1 LED on 2 strips, and 2 LEDS on the other strip. So the LEDs have to be shorted.

Ordered 10 LEDs for about $25............
http://www.ebay.com/itm/SAMSUNG-LUME...UAAOSwax5YnfL~

Let you know how I make out when the LEDs come in in a couple weeks.....

[thoma]

Re: Samsung UN32F5500 smart TV no backlight

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d2ge-320sc0-r3 google a lot of informations !

[longson90]

Re: Samsung UN32F5500 smart TV no backlight

i have a samsung ue32f6200ak turns on with image on the screen and sound but no back lights

[paulstef]

Re: Samsung UN32F5500 smart TV no backlight

when you find the one blown I would highly recommend putting about 20 diodes in series to limit the voltage strain on the LEDs. I am currently running mine with 12 LEDs burnt out and it's still lots bright (limited the current with resistors).

Since I believe the LED controller is a current controller, diodes in series or resistors will only help if the voltage from this controller is maxed out, otherwise it will just keep increasing the voltage in order to maintain the current through the LEDs at the level it's supposed to be. The right thing would be to lower current as Bud said via menu or electronically.

I have 7 shorted LEDs, will try to replace just the diodes with some from spare strips from another TV.

[budm]

Re: Samsung UN32F5500 smart TV no backlight

To reduce the current through the LEDs which will extend the life of the LED is to go to on screen user manual and reduce the backlights level.

[paulstef]

Re: Samsung UN32F5500 smart TV no backlight

Maybe we could find out how the current limiting works and lower the LED current.

[mrhappypants]

Re: Samsung UN32F5500 smart TV no backlight

i started with one open LED i fixed it by bypassing with 5 diodes. I week later it blew a whole bunch short circuited. I have a feeling after one goes the whole damn thing goes to shit, but I'm hoping not.

when you find the one blown I would highly recommend putting about 20 diodes in series to limit the voltage strain on the LEDs. I am currently running mine with 12 LEDs burnt out and it's still lots bright (limited the current with resistors).

P.S. it's not that hard getting at the LEDs, just use a few butter knives and start at one corner. Slowly work your way around one clip at a time and use the knives to keep it separated as you go.

[paulstef]

Re: Samsung UN32F5500 smart TV no backlight

Ok, so they are in series on the PCB for the first 4 strings and then 2 strings in series inside the panel. That answers my question. I have definitely open LEDs on string 1 :-|

Thanks!

[mrhappypants]

Re: Samsung UN32F5500 smart TV no backlight

the only pins that power anything are 1+(power), 4-(controlled ground). So the scheme does work it just seems confusing at first.

I say "controlled ground" because it is actually the ground that is switched on and off to control the backlight.

[mrhappypants]

Re: Samsung UN32F5500 smart TV no backlight

okay. i'll try and clear this up. The power supply puts out the full voltage of 160V on 1+, it goes out to string 1, then comes back on 1-, then on the PCB 1- and 2+ are connected together. (Flip over the board and you can see the trace). Then from 2+ to 2- it goes through string 2, 3+ to 3- goes through string 3. Then it gets a little weird. 4+ goes through string 4 then without coming back to the PCB it goes through string 5, then comes back to 4-.

1+ >> string1 >> 1- =[PCB]= 2+ >> string2 >> 2- =[PCB]= 3+ >> string3 >> 3- =[PCB]= 4+ >> string4 >> string5 >> 4-

[paulstef]

Re: Samsung UN32F5500 smart TV no backlight

there are 5 strips not 4.

they are all in series, but 4 and 5 are connected in series inside the panel. So when you test +4 -4, you are actually testing 18 LEDs not 9 LEDs like the other ones. You would have to give it 40 volts probably to get them to light up.

Thing is I wanted to be sure they are faulty before opening up the panel.

+-3 and +-2 both light up at about 20 to 25V, with +-2 being brighter than +-3.

You say they are all in series inside the panel (i.e. not on the PCB). Then why are there 2 wires for (supposedly) each of the strings coming from the PCB?

[mrhappypants]

Re: Samsung UN32F5500 smart TV no backlight

there are 5 strips not 4.

they are all in series, but 4 and 5 are connected in series inside the panel. So when you test +4 -4, you are actually testing 18 LEDs not 9 LEDs like the other ones. You would have to give it 40 volts probably to get them to light up.

[paulstef]

Re: Samsung UN32F5500 smart TV no backlight

All 4 strips are connected in series, the one I work on has one strip with shorted out LED, and another strip has open LED, very common failure.
https://www.badcaps.net/forum/showthread.php?t=46403
You will have scrape off the white paint to make contact with each LED legs, the LEDs in each strip are connected in series.

They must be connected in series on the PSU PCB then , correct? Or why would there be 10 wires going from PSU to LEDs?

[budm]

Re: Samsung UN32F5500 smart TV no backlight

All 4 strips are connected in series, the one I work on has one strip with shorted out LED, and another strip has open LED, very common failure.
https://www.badcaps.net/forum/showthread.php?t=46403
You will have scrape off the white paint to make contact with each LED legs, the LEDs in each strip are connected in series.

[paulstef]

Re: Samsung UN32F5500 smart TV no backlight

Same problem. Would be nice to know the EXACT wiring of the strips. My panel is not open yet though.

Tested them all with 20 to 25V.
+-4 does not light up
+-3 does light up
+-2 does light up
+-1 does not light up
IF1 IF2 does not light up

They don't seem to be all equal, or why would they give a different name to the last pair?

[Truncatedhose]

Re: Samsung UN32F5500 smart TV no backlight

How hard is to get to the LED strips in this model? Can you describe the process for me? Thanks!

[siddhu]

Re: Samsung UN32F5500 smart TV no backlight

Hi, I have the same tv UN32F5500 with same issue, flash light test passed so back light issue.
Help me with further trouble shooting.
Need help to check if the output from led driver is proper.
If that is fine then need help to check if the led strips are fine.

[thoma]

Re: Samsung UN32F5500 smart TV no backlight

LED Stripes for LED TV

http://www.shopjimmy.com/tvs/tv-led-light-strip

http://www.ebay.com/bhp/led-backlight-strip

[Terryfictv]

Re: Samsung UN32F5500 smart TV no backlight

Yes,indeed we are all in the same bind!I have a UN32F series with all
strips bad. Part number D2GE-320SC0-R3 Mfr.by LUMENS.We need a source,
even China will do!

[budm]

Re: Samsung UN32F5500 smart TV no backlight

For the 32 in it is more likely to be ONE big string.
For example on this Samsung in the thread, it has one shorted LED, and one open LED.
https://www.badcaps.net/forum/showthread.php?t=46403