Samsung UN32F5500 LED TV Backlight issue

**ReeceyBurger123** · 08-24-2015, 02:09 PM

Re: Samsung UN32F5500 LED TV Backlight issue

Ahh more crappy failed leds I see it too often. You can use your DMM to test each bulb to see which ones are S/C.

**siddhu** · 08-25-2015, 03:27 PM

Re: Samsung UN32F5500 LED TV Backlight issue

Hey, there are 5 led strips with 9 leds on each.
Is it 200-220 V in Pin 12 input to LEDs are expected?

**siddhu** · 08-25-2015, 03:30 PM

Re: Samsung UN32F5500 LED TV Backlight issue

Originally posted by ReeceyBurger123

Ahh more crappy failed leds I see it too often. You can use your DMM to test each bulb to see which ones are S/C.

yeah i tested the LEDs with DMM and found the culprit. now im trying to replace.

**mrhappypants** · 08-26-2015, 07:36 PM

Re: Samsung UN32F5500 LED TV Backlight issue

did you order a whole strip and if where? does anyone have the part number for the individual LEDs on this model?

**mrhappypants** · 08-28-2015, 06:51 AM

Re: Samsung UN32F5500 LED TV Backlight issue

well i can't find the spec for these things anywhere... they don't look like the standard samsung 3535 or the 5630.. so i started doing some testing.

from what i can tell the whole backlight system on this tv (UN32F5500) is poorly designed. From testing I can tell each LED is meant to run at 2.9V.. 3.1V if you really push them, but that is not what is happening. They feed 45 LED's 160V, doing the math that comes out to 3.55V. So it is little wonder why they fail.

I'm only new to this tv repair stuff so maybe there is something I'm missing here with backlight design and if so I would love some feedback.

**TTAN** · 04-12-2016, 09:34 AM

Re: Samsung UN32F5500 LED TV Backlight issue

Hello,

My boss said he had a bad Samsung tv, which sounded like a bad cap, but turns out I'm having a similar issue with the backlight. The unit has 5 bad leds over 3/5 led strips, tested with my fluke117 (via diode+resistance functions) and ~3v battery pack.

I've measured the power pins 1-16 to the led array. All produce zero volts aside from pin 11: 188v, pin 12: 213v. when I measure min/max it cycles ~+/-14 v. Just an observation Autorange mode seems to light up the top strip while manual does not.

Am I correct to assume that I can just replace the 5 bad leds? Should I check anything else out? I was thinking one of these http://www.digikey.com/product-searc...1516-1028-6-ND.

Are there better parts? I usually like to order ~50% more then I need just in case, but 1.69 apiece starts to encroach on my boss's throw it away mentality.

**TTAN** · 04-23-2016, 12:36 PM

Re: Samsung UN32F5500 LED TV Backlight issue

Originally posted by TTAN

Hello,

My boss said he had a bad Samsung tv, which sounded like a bad cap, but turns out I'm having a similar issue with the backlight. The unit has 5 bad leds over 3/5 led strips, tested with my fluke117 (via diode+resistance functions) and ~3v battery pack.

I've measured the power pins 1-16 to the led array. All produce zero volts aside from pin 11: 188v, pin 12: 213v. when I measure min/max it cycles ~+/-14 v. Just an observation Autorange mode seems to light up the top strip while manual does not.

Am I correct to assume that I can just replace the 5 bad leds? Should I check anything else out? I was thinking one of these http://www.digikey.com/product-searc...1516-1028-6-ND.

Are there better parts? I usually like to order ~50% more then I need just in case, but 1.69 apiece starts to encroach on my boss's throw it away mentality.

Repaired all the broken LEDs. After plugging them all into their sockets, connected to just the power supply/inverter, still no love. I was under the impression if the main and tcon board were unplugged, then the backlights should all be lit up. The only power I get in this setup up is the pins listed above. Do I need the main board to be plugged in? I ran out of time today to check that. If my inverter section of my psu is busted, anyone know what the likely culprit is? I wasn't sure how to test mosfets in circuit, but I was fairly certain all the caps transistors and diodes were good. I didn't measure any out of circuit yet, as I was hoping replacing the LEDs would do it.

Your thoughts would be greatly appreciated.

**budm** · 04-23-2016, 01:52 PM

Re: Samsung UN32F5500 LED TV Backlight issue

This UN32F5500 power supply-LED driver board should power up the backlights when it is not connected to the main board, it has built-in pull up resistors for self test.

**vinceroger69** · 04-23-2016, 02:11 PM

Re: Samsung UN32F5500 LED TV Backlight issue

Have you double checked your new leds? its so easy to fit one wrong ive done it before.

**ReeceyBurger123** · 04-23-2016, 02:12 PM

Re: Samsung UN32F5500 LED TV Backlight issue

Originally posted by vinceroger69

Have you double checked your new leds? its so easy to fit one wrong ive done it before.

+1 I also made a couple of mistakes.

**TTAN** · 04-25-2016, 07:48 AM

Re: Samsung UN32F5500 LED TV Backlight issue

Originally posted by siddhu

Hey, I opened my TV back panel and there are 5 LED strips.
I could see one of those strips is burnt. I have ordered for it, which i will get it in few days...

Originally posted by ReeceyBurger123

+1 I also made a couple of mistakes.

Thanks everyone for your input. When my dmm is in auto range, and I check voltage on the only active pins, the top led strip lights up. I ended up swapping all 5 through the top slot to make sure they light up. The color isn't as blue, but I haven't glued the lens back on yet either. I'm waiting to glue, just in case I blow one. I have a feeling that the led side of the psu has an issue since it doesn't light any of the strips up. So my game plan is to des older and check with multimeter. I've identified all replacement components except the large mosfet as I have difficulty reading the writing on it. Tbh I haven't figured out yet how to measure them to see if they are good or not. I'll write back when I know more.

Thanks

**TTAN** · 04-27-2016, 04:21 PM

Re: Samsung UN32F5500 LED TV Backlight issue

Some updates.

I checked my notes, and I realized that I found all the replacement parts, sold in the shopjimmy kit, including mosfets already.

http://www.digikey.com/product-searc...t=497-12246-ND
http://www.digikey.com/product-detai...186-ND/3152447
http://www.digikey.com/product-detai...1-1-ND/3060933
http://www.digikey.com/product-detai...0CT-ND/3907888

I had time to test components, by desoldering 1 leg.

The fuse, tested continuity with low resistance (3 ohms).
Resistors, I'll list location, and the measured value, with the listed value
RM813 (location) 81.5kohm (measured), 82kohm 5% (listed)
R9110 3.5 ohm, 3.6 ohm 5%
r9109 0.5 ohm, 0.4 ohm 5%
rm801 0.4 ohm, but subseq readings were 0.7ohm , 0.44ohms 1%
rm802 0.4 ohm, but subseq readings were 0.7ohm , 0.44ohms 1%

Diodes, all were SR(SB) 320, voltage measured in one direction, O.L. in the other.
DM858c 0.348v, remeasured at 0.355v
DM859c 0.351v
DM860c 0.355v

I assume everything measured is within spec, If I am incorrect please let me know.

I did not have time to desolder the mosfets from the board to see if they are functional.

the shop jimmy part kit can be found here http://www.shopjimmy.com/samsung-bn4...repair-kit.htm
They also have a hires image of the board, front and back here, which can be used to confirm resistor values.http://www.shopjimmy.com/samsung-bn4...upply-unit.htm

Thanks for all the help so far.

**victor_cj** · 04-28-2016, 02:55 AM

Re: Samsung UN32F5500 LED TV Backlight issue

I used LATWT470RELZK led to repair the led strips.
https://www.youtube.com/watch?v=CCw1Ks4ZBXc

Attached Files

**TTAN** · 04-28-2016, 04:53 AM

Re: Samsung UN32F5500 LED TV Backlight issue

Originally posted by victor_cj

I used LATWT470RELZK led to repair the led strips.
https://www.youtube.com/watch?v=CCw1Ks4ZBXc

The temp of the LEDs seem to match very well. I couldn't tell which ones were replaced when they were lit up.

Thanks for sharing

**o0larry0o** · 05-12-2016, 10:25 AM

Re: Samsung UN32F5500 LED TV Backlight issue

Originally posted by victor_cj

I used LATWT470RELZK led to repair the led strips.
https://www.youtube.com/watch?v=CCw1Ks4ZBXc

How do you unsolder the old one and solder the new one back ?
the one I have t replace is just next to the connector ...

**TTAN** · 06-04-2016, 07:15 AM

Re: Samsung UN32F5500 LED TV Backlight issue

Originally posted by o0larry0o

How do you unsolder the old one and solder the new one back ?
the one I have t replace is just next to the connector ...

Personally I scraped old the led with soldering iron then cleaned the contact. Use caution as you can damage the contact and may need to rebuild it. When you put the new one on, use flux. It's essential to get the solder to flow under the contacts on the led. LEDs melt super easily, so I wouldnt apply the iron directly to them, let the solder flow into the contacts. Double check polarity first as well. After that I used electronics grade silicone to glue the lens on again. Good luck buy extra LEDs in case you damage the first couple. May take practice.

**TTAN** · 06-04-2016, 07:21 AM

Re: Samsung UN32F5500 LED TV Backlight issue

Just an update on the tv I was working on. I fixed it and it's back in its home.
The leds I used were not a great match for the existing ones. They were more white or yellowish when compared to the purplish factory ones. Even across a single batch there was variability in regards to brightness, and color temp. I assume part of this is due to damage incurred during soldering. I improved my technique by the end. I cannot recommend the LEDs I mention in the previous post. Perhaps if all the strips were redone the color wouldn't matter, but 45 LEDs x 1.2 leds for mistakes at 1 dollar a price makes that not worthwhile. I hope this helps.

**Territup** · 01-17-2018, 06:53 PM

Re: Samsung UN32F5500 LED TV Backlight issue

Well my Samsung UN32F5500AFZA Backlights went out yesterday everything else was fine so i opened it up and this is what I have, these pictures are from today. Luckily I unplugged it last night or probably wouldn't be here posting this.

Attached Files