Samsung UN50KU6300F constant reboot, bad backlights?

[nomoresonys]

Well lets make sure on that resistor, is it visible on here, if not what are the colors on it?

[x_orange90_x]

Well lets make sure on that resistor, is it visible on here, if not what are the colors on it?

Attached is a photo of it. I don't really understand how to interpret the readings from either of my meters as far as resistance goes. I don't get a clear "600 M ohm" or even .600. I get whole numbers with decimals and they'll move around between 20 and 200 ranges

[x_orange90_x]

I tested the SK34 diode on the bottom and it appears to be bad. It checks .298 both directions with one meter and 4.8 both directions with my other meter.

I have a spare board with a similar size but it's an SK510C. Could I safely use this in place of the SK34?

[nomoresonys]

Grab the data sheets of both and compare them.

[nomoresonys]

I tested the SK34 diode on the bottom and it appears to be bad. It checks .298 both directions with one meter and 4.8 both directions with my other meter.

I have a spare board with a similar size but it's an SK510C. Could I safely use this in place of the SK34?

I assume that was in circuit, if so unsolder it and test it again, seems bad.

[nomoresonys]

Here's one resistor chart, pretty easy to use, check some other resistors to see if you get a correct reading, wondering if your meter battery is ok: https://kiloohm.info/smd4-resistor/1004

[nomoresonys]

Shit, my bad, that one is for surface mount, let me grab the thru hole one, here: https://www.digikey.com/en/resources...tor-color-code

[nomoresonys]

Is it black-blue-silver-gold, I get .06 ohms, if those colors are correct, then even 1.2 ohms is way out of specs, then as usual when a reading seems off in circuit lift a leg and check ooc.

[x_orange90_x]

Is it black-blue-silver-gold, I get .06 ohms, if those colors are correct, then even 1.2 ohms is way out of specs, then as usual when a reading seems off in circuit lift a leg and check ooc.

black, blue, silver, gold is correct. When I looked it up I got 600 M ohms. Maybe I did something wrong


I checked other resistors on the board and got similar oddball readings. I think the resistor ok. That one diode on the bottom has been mentioned on these forums several times as causing these symptoms. It's surface mount, so if I take it off to test I'd be replacing it as well.

[nomoresonys]

Absolutely, I do believe that diode is bad.

[x_orange90_x]

Absolutely, I do believe that diode is bad.

I'm trying to source a replacement right now. I'm going to call a local electronics store later to see if they carry these, but if they don't I'll have to order some. The SK310C I asked about is too far off spec wise. Comparison of those two are attached

Ir is blank on the datasheet for the SK310C.

[nomoresonys]

Maybe there: https://www.aliexpress.us/w/wholesal....home.search.0

[x_orange90_x]

I replaced the diode on the bottom and I STILL have the same symptoms!

Edit: I removed a leg of that resistor and checked it. It reads 0.00 ohm 😑

[diif]

black, blue, silver, gold is correct. When I looked it up I got 600 M ohms. Maybe I did something wrong


I checked other resistors on the board and got similar oddball readings. I think the resistor ok. That one diode on the bottom has been mentioned on these forums several times as causing these symptoms. It's surface mount, so if I take it off to test I'd be replacing it as well.

Double check the resistor value using one of the many available websites.

[x_orange90_x]

Double check the resistor value using one of the many available websites.

using the tool on DigiKey I get either 600M ohms or .06 ohm depending on the color is the third band, which I'm not positive if it's grey or silver. Can you tell what color it is?

Also, my reading of 0.00 ohms means my resistor is bad, right?

Edit: it has to be silver because that's .06 Ohms. Grey would be 600 MegaOhms. I can't however find a .06 Ohms resistor online.

[x_orange90_x]

It looks like it can't be either of those. 600 M ohms would be a huge resistor, and from what I'm finding .06 ohm doesn't even exist.

I can't find a schematic for this board either

Edit: wow this is frustrating. I can't find a schematic, therefore I can't see on paper what the value is supposed to be. Likewise, searching for the board number and "R9022" turns up absolutely nothing. And to top it off I'm finding this exact same model board with a completely different 5 band resistor instead of the 4 band I have.

[x_orange90_x]

I gave up on diagnosing the original board and just ordered one from eBay. I put it in last night and the tv is working great.

My advice to anyone else with this model power supply is to just get a replacement. There's too many things that fail on it and getting it working may only buy a little bit of time before another component fails.

[nomoresonys]

Glad to hear it, Indeed when you figure all the time that can be spent trying to troubleshoot, if a board is available for a fair price, it sure can be the best way to go, it may also preserve a little sanity, lol.

[nomoresonys]

My guess is the backlight driver IC on the non-working powerboard may be bad, seems like you checked everything else.

[x_orange90_x]

Glad to hear it, Indeed when you figure all the time that can be spent trying to troubleshoot, if a board is available for a fair price, it sure can be the best way to go, it may also preserve a little sanity, lol.

Preserve sanity is right! I got pretty pissed at spending ALL that time and it did exactly the same thing. Thank you for all your help and guidance!