Samsung UE32F5000 (UK model) with no display. Power supply is OK.

**budm** · 02-09-2016, 01:49 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

'the display reads 0.777 for each LED then with the probes reversed I get 1 and the LED I am testing gives a faint glow, would that sound about right to you' That reading is for the protection diode in parallel internaly with the LED but connected in Anti-Parallel.
So if each one light up when tested but it can be that the LED strings are still not making the connections. 220V is more than enough to light the LED strings.

**budm** · 02-09-2016, 01:50 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

What is your power supply-LED driver P/N? BN44-?????

**ralphup** · 02-09-2016, 01:53 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

OK found this on an ebay sellers site...

TO TEST PUT 20VOLTS ACROSS LED BAR IT WILL THEN LIGHT (ONE OF THE 5 BARS WILL BE FAULTY) GIVING NO LED BACK LIGHT

I originally tried testing each strip physically removed in-turn with a variable DC power supply that max's out a 20v but I only ever got FAINT glowing from the LEDS on the strip...
3 x 9 = 27v so I would have thought that the LEDS would give a decent glow at 20v per strip! what the $#%$ am I doing wrong?!?!?!

**budm** · 02-09-2016, 01:56 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

The main key is that even at 20V as long as all the LEDs on that strip are lit then it means you do not have open circuit in that strip. Each LED strip are attached to the junction PCB with sockets, so you may want to inspect the connections at those sockets.

**ralphup** · 02-09-2016, 01:59 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Originally posted by budm

What is your power supply-LED driver P/N? BN44-?????

not at work now, doubt I can get back to this until next week, but its just bugging me now as I thought this would be an easy fix, and Im sure it still is.

**ralphup** · 02-09-2016, 02:00 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Originally posted by budm

The main key is that even at 20V as long as all the LEDs on that strip are lit then it means you do not have open circuit in that strip. Each LED strip are attached to the junction PCB with sockets, so you may want to inspect the connections at those sockets.

OK that is my next step then... but would you expect a Faint as in barely visible unless the room is in darkness, or decent glow?

**budm** · 02-09-2016, 03:01 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Very very faint glow, the correct way to power up the LED strip or the LED is to use constant current power supply (I test them at 50mA), if you use the power source Voltage based on the QTY of the LED on the strip without current limiter, if the strip has one or two shorted out LED then you will have lots more current flowing through good LEDs and damaged them. LED is not Linear device.

**ralphup** · 02-10-2016, 01:03 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Very very faint glow

do you mean at test 20v I will only see a Very very faint glow?

**stj** · 02-10-2016, 01:23 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

what's the current limit on your psu?

**flocko** · 02-10-2016, 01:34 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

do you mean at test 20v I will only see a Very very faint glow?
You do the maths 9 x LEDs at 3.5v (9x3.5v =?)

**budm** · 02-10-2016, 01:49 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Originally posted by ralphup

Very very faint glow

do you mean at test 20v I will only see a Very very faint glow?

I expect them to be very very dim or barely lit, if you want to drive the strip with about 30~50ma of current so you can see them on brighter then you can just have to calculate the value of total Vf of the LED, the Vdrops on the current limiter resistor based on what power supply you have.
The key point is that you are looking to see if you have open circuit in the LED strip you are testing, if one or more of the LED has open circuit then none pf them will light up.

**ralphup** · 02-10-2016, 04:14 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

thanks all! I will have to re-test, but cant look at it until next week.

I will let you know how things go, but a big thanks to all the people giving great advice! also to budm for his patients and willingness to share his knowledge and expertise

**ralphup** · 02-12-2016, 10:59 AM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

So I got time today to re-test, and using the 3v Double AA Battery test method I tested all LEDS, I went across ONE LED at a TIME no issues, then I did ONE LED then the Adjacent, and found a couple that seemed to have a mild short i.e. the The First LED on its own was Bright, the Second LED on its own Bright, but then doubled up One to Two, the Second LED would give a Faint glow so I took them off the Strip and used DIODES to bridge the Pads but Still NO Back Light ARRRHHHGGG!!!

I have ordered http://www.ebay.co.uk/itm/1217758073...%3AMEBIDX%3AIT so will substitute the Diodes for these and see where I go, but its still looking Bad! any further help guys??

**ralphup** · 02-12-2016, 01:27 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

YEAH! GOT it... BOO need 4 new LEDS!

After proving ALL LEDS with 3volt AA battery tester, put all back together, still no dice!

Turns out I did have my Diodes reversed! got it by plugging in each strip, with TV Powered ON, then measuring between Chassis Gnd and Top Strip +ve, then Chassis Gnd and Top Strip -ve, then moved down to Second Strip +ve, then Chassis Gnd and Second Strip -ve, then Third Strip +ve, then Chassis Gnd and Third Strip -ve got DC Voltage stepping down from 200V to 170V to 140V (readings are Approx)

Found I had no reading from 3rd strip, so reversed Diodes and got a reading, then Forth and Fifth Strip +ve, then Gnd and Strip -ve. When finished had no voltage from 4th strip -ve and 5th strip positive, bend the strip -ve PIN and TADA we have a Winner

hope the ones I ordered from EBAY will be OK!

Attached Files

**budm** · 02-12-2016, 01:32 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Originally posted by ralphup

YEAH! GOT it... BOO need 4 new LEDS!

hope the ones I ordered from EBAY will be OK!

But per your testing, 4 of them are bad due to shorts or open?
I am glad you finally figured it out.
Make sure to turn down the backlights level in the on screen user manual down to at least 80% or less to extend the life of the LEDs.

**ralphup** · 02-12-2016, 01:46 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Originally posted by budm

But per your testing, 4 of them are bad due to shorts or open?
I am glad you finally figured it out.
Make sure to turn down the backlights level in the on screen user manual down to at least 80% or less to extend the life of the LEDs.

At least 2 where yes, as for the First two I did at the beginning of the week, that might have been just me and my ham fistedness!

It will be the first menu I select once I have the new LEDs installed and re-assembled!

budm, do you think the LEDS in my previous link, I have ordered from Ebay will be suitable?

**flocko** · 02-12-2016, 02:46 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Have you not seen my listing on ebay 252282953741 now with the three most common LEDs used on all makes and models and can be used on strips of every size

**budm** · 02-12-2016, 03:24 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Originally posted by ralphup

At least 2 where yes, as for the First two I did at the beginning of the week, that might have been just me and my ham fistedness!

It will be the first menu I select once I have the new LEDs installed and re-assembled!

budm, do you think the LEDS in my previous link, I have ordered from Ebay will be suitable?

They look big and not sure about the color temp, and you probably will not be able to put the LENS on top.

**ralphup** · 02-12-2016, 04:45 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Originally posted by flocko

Have you not seen my listing on ebay 252282953741 now with the three most common LEDs used on all makes and models and can be used on strips of every size

yeah and they are pricey! I have now order 5 x 1W Super Bright White High Power LED Chips Beads 12000-15000K for 2 quid...

and from what I can tell the lens that are fitted can be popped off.

**budm** · 02-12-2016, 04:48 PM

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Lets us know how those LEDs work out.

Samsung UE32F5000 (UK model) with no display. Power supply is OK.

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