UN55D6000 Blinking Standby Light

[mmartell]

Re: UN55D6000 Blinking Standby Light

Most 2000 count meter (max reading 19.99V, etc.) cannot drive white LED

What do you mean by that and is that what I have ?

[Ltank]

Re: UN55D6000 Blinking Standby Light

With this TV the power supply is not able to run by itself even if jumpered with resistors to simulate signals from the main board? This set uses the same Power Supplyas the
UN55D6003, But different main boards. I have a UN55D6003 in shop with the samepower supply that had the same problems,I too replaced the power supply and it had the same problem. Jumpering the power supply by it self the A side 5vdc was stable. The B side
5vdc cycled on/off not staying on long enough to get higher voltage fo the backlights.
If we can figure this out it willhelpalot op people, Including me! I guess when I get slack time Iwill disect it best I can checking all thet I can but without schematics I can only go so far, Not sure about EEPROMs availability on the power supply

[Ltank]

Re: UN55D6000 Blinking Standby Light

The MannualI posted forthe UN55D6003 shows on page 4-2 on flowchart that is A side is
bad replace SMPS if B side is bad replace main board. I guess the PS supplies A side 5v stby to main board then the Main board supplies the Bside back to the power supply then
is strange but it may be whats happenig. When My dad gets well i willget back to shop and give a good 5vdc input to main board and check voltage regulators and replace what is needed and reinstallit and check again!

[mmartell]

Re: UN55D6000 Blinking Standby Light

They're saying to replace main because no B5v probably means no PSON sent from main.

I think I've got some failed led's and the supply will not run without a load.

[tom66]

Re: UN55D6000 Blinking Standby Light

What do you mean by that and is that what I have ?

Yes, your meter is 2000 count so may not be able to drive white LEDs. That is just my experience with them.

[mmartell]

Re: UN55D6000 Blinking Standby Light

Ok maybe I'm dense but what does "2000 count" mean like four digit display or... ?

[mmartell]

Re: UN55D6000 Blinking Standby Light

How much voltage can an LED light safely handle ? I have a quick and dirty idea...

As seen in one of the pics I posted in this thread there are four wires going to the backlighting. The center two are connected together at the board so if I assume (!) there are two led strips then I can isolate the individual strips by manipulating the harness.

The board says there is 330v at the connector or 165v per strip. Is it safe to run full voltage through one strip ?

[tom66]

Re: UN55D6000 Blinking Standby Light

2000 count MAX reading is 19.99V i.e. it can read from 00.00 (zero) to 19.99 (1999) and has 2,000 total counts, or 1.999V max from 0.000 to 1.999, and so on.

I have a 6,600 count meter, many high end meters do 10,000 to 40,000 counts.

Each LED only rated around 3.5V to 4V but the key is they are non-linear current driven devices which means just 100V would not make the 1/4 bright they would not light up at all.

I don't know the configuration of this panel but if you give the model of the LCD panel (probably SAMSUNG, AUO, CHIMEI... plus model number) then configuration of LEDs might be available in my panels datasheet listing or another site.

[mmartell]

Re: UN55D6000 Blinking Standby Light

Gotcha on the 2000 count.

Here's the sticker on the panel itself.

[tom66]

Re: UN55D6000 Blinking Standby Light

Unfortunately, I can't find a datasheet for that; probably a custom part for that TV .

[mmartell]

Re: UN55D6000 Blinking Standby Light

Each LED only rated around 3.5V to 4V but the key is they are non-linear current driven devices which means just 100V would not make the 1/4 bright they would not light up at all.

Actually I was trying to do the opposite - double the rated voltage by only running one string at a time at full voltage. Would that just destroy the LED's ?

[tom66]

Re: UN55D6000 Blinking Standby Light

That would probably kill a great many LEDs, unless the PSU is current limited. Even then, damage would likely occur.

[mmartell]

Re: UN55D6000 Blinking Standby Light

Thanks for that tom, I'm going to take off the panel then. Here's hoping I don't crack the lcd

[mmartell]

Re: UN55D6000 Blinking Standby Light

Well that was harrowing. I can't be sure I didn't damage anything I guess I won't know until I get it back together.

The LED strips are arranged as they are in another thread where another user did a teardown of his UN55D6400 - one strip on the right and one strip on the left. Each strip consists of 100 LED lights.

The right strip (as seen from the front) has all working LED's.

The left strip has 20 dead LED's in no particular order, except that all but one are on the lower half.

Two have failed open which I suppose presents the same to the Power Supply as not being connected at all.

Is it safe to short the two open LED's and see if the power supply will light up the rest even though the load is 10% smaller than designed ?

[mmartell]

Re: UN55D6000 Blinking Standby Light

Some pics...

[tom66]

Re: UN55D6000 Blinking Standby Light

How many LEDs each side? 165V total I expect about 40~50 LEDs. I would say it is OK to jumper a couple, any more may risk failure of further LEDs.

[mmartell]

Re: UN55D6000 Blinking Standby Light

100 LED's per side so 200 total of which 20 have failed (my meter lights them, not too bright but enough). Two of the twenty have failed open, the rest short.

The supply is rated at 330v total or 165v per string.

[mmartell]

Re: UN55D6000 Blinking Standby Light

How do you explain it being so low (1.65v per led) ?

[tom66]

Re: UN55D6000 Blinking Standby Light

Probably 50 LEDs/string but two strings in parallel.

[mmartell]

Re: UN55D6000 Blinking Standby Light

What's the easiest way to present a dummy load based on the fact 20 led's are out so I can test the power supply and the remaining led's ?