Samsung UN55D6000SF - Success

[Audioplus]

Set was blinking LED, no response. Performed system restore with Menu, Mute, 1, 8, 2, Power and success!

[tom66]

Re: Samsung UN55D6000SF - Success

With just a blinking LED, how could you see service menu?

[Audioplus]

Re: Samsung UN55D6000SF - Success

Tom
I don't know, it would not respond to hard button commands, owner didn't have the original Samsung remote. I had one, performed the reboot process, it powered up to main menu and functions (I didn't mean the service menu), so I assume it was an Eprom issue?
And to correct myself further, it had the blinking red power LED, couple times continuously.

[mmartell]

Re: Samsung UN55D6000SF - Success

I would be surprised if this was not a coincidence and the issue pops up again. I don't think entering the service menu blindly restores anything.

[Audioplus]

Re: Samsung UN55D6000SF - Success

It worked for a day or two, now it's not working, flashing LED Power indicator.
Any ideas on this one?
Power supply ? The optical output flashes when unit tries to recycle, main board

[tw2005]

Re: Samsung UN55D6000SF - Success

It worked for a day or two, now it's not working, flashing LED Power indicator.
Any ideas on this one?
Power supply ? The optical output flashes when unit tries to recycle, main board

I think there's another post somewhere where it's been woorked out the LED strip lighting shorts out.

We've got a 55D6000 at work (we're not TV techs) from another worker and it fires up, then after runing for an hour or less shutsdown then endlessly restarts and as soon as the lights come on it resets, relays clicking away.

We removed the connector to the LED lighting and it produces the same endless clicking of the relay, so we're confident that's what it's going to be.

Yet to strip this down and get to the LEDs, hoping this weekend .

Already tried PSU with no joy, even though I said not to replace it, someone else knew better.

From the few articles I've read, everyone heads for the mainboard and PSU and the fixes I've read under wty involved screen replacement so since the lighting is integral of the panel, that would make sense that is how Samsung would repair it.

I don't think the strips are available, but hoping someone here comesup with a good workaround.

yet another expensive dud. I think over here $2500-3000 new, not even 3 years old.

nice picture when working.

[tw2005]

Re: Samsung UN55D6000SF - Success

Amazing what a search will find, search UN55D6000, https://www.badcaps.net/forum/showth...ight=un55d6000

[budm]

Re: Samsung UN55D6000SF - Success

He has two open circuit LED in one of the string and so he bypass the open LEDs with jumper wire.
These LEDs tend to go open circuit or have the wire leading into the panel that has nicked on the wire insulation and shorted to the chassis.
You can put AMP meter is series with the LED string to see which one has no current draw, that will be the one with open LED, if the LEDs in the string shorted out the rest of the LEDs in that LED string will be bright and the LED driver will go into shut down.
https://www.badcaps.net/forum/showpo...4&postcount=95

[mmartell]

Re: Samsung UN55D6000SF - Success

Nah in my case I replaced the individual leds. All in all not too bad but definitely a learning curve.

[Audioplus]

Re: Samsung UN55D6000SF - Success

I tried jumping pins 2 & 18, 4 & 18, etc. no LED lights, no AC power indication. Disconnected T-Con from Power, same blinking red Power LED, and fiber optic digital audio output flashes.
Main Board issue?

[johnboy1313]

Re: Samsung UN55D6000SF - Success

As was said above, more than likely one or more LED on the strip has failed. You won't find the fault jumping the pins on the connector. You have to find the bad LED(s) and bypass it/them.

[Audioplus]

Re: Samsung UN55D6000SF - Success

I checked Bud's posting on checking the LED strips with multi meter, what is the one cable connected to (looks blue out of coincidence?), ground on chassis or ?

[Audioplus]

Re: Samsung UN55D6000SF - Success

Tom, I found your website with manuals, tried forcing the backlight by disconnecting power to main board, no luck. Is this indicating that the PS is bad?

[mmartell]

Re: Samsung UN55D6000SF - Success

It is indicating a Power Supply OR Backlight issue as if the two were good the backlights would light in this model.

[Audioplus]

Re: Samsung UN55D6000SF - Success

Found a UN55D6050 (cracked panel) and replaced the power supply and panel lights up, no graphics or menu, replaced the T-Con same issue. Replaced the main board, and switched back to original T-con, it works.
So I replaced the PS and Main board in the Samsung UN55D6000SF that worked temporarily with the reset command. Weird . . . .
I also assume that the T-Con in the 6050 must be a little different than than the 6000? I couldn't get a picture, so reverted back to the original after replacing main board.
Don't mean to sound confusing, but a PS and Main Board later, the unit is working.
Anyone have any ideas why it worked temporarily, and then totally failed?

[johnbinsc]

Re: Samsung UN55D6000SF - Success

Audioplus,
I have no idea why changing out the PS and Main board on your UN55D6000SF brought the backlight back to life. The only thing I can guess is that the "backlight failure detection" circuit on your new PS board is less sensitive, and you have a backlight LEDs are on the edge but not yet gone.

Did you try all combinations of PS with the "new" main board? I am curious if it ONLY works with both the "new" main and PS from the UN55D6050.

I have studied the schematic for the BN44-00428b power supply (available on this site and also electrotanya), which is very similar to the BN44-00424a power in the D6000 series TVs. The main difference is that the 00428b PS has 4 independently dimmable LED backlight supplies for the 4 quadrants, while the 00424a has only the single LED backlight circuit.

From my study, the cycling is because upon power on, the LED driver IC (IC9101S on the D6000) detects a no current failure in the LED backlight circuit, and raises it's "FLAG" output line. FLAG drives the "main power supply shutdown" circuit (see lower right corner of page 3 of the 00428b schematic, it is almost identical in the D6000, right down to the component labels), which then pulls PS-ON back low asserting the power supply back into standby mode (i.e. A5 stays on, B5, B13, Vamp, and Vdrv shut off). This same "main power supply shutdown circuit" can also be triggered on overvoltage on B5 and B13. Note that there is a timer in the shutdown circuit, such that once B13 collapses, the main supply to restart once CM859 (00424a) or CM861 (00424b) discharges through RM880 (both) to a level that allows QM853 to turn off and PS-ON to no longer be asserted low.

Note also that this power on/off cycling should happen on the 00424a power supply with it disconnected from the main board. If there was no problem with the backlight LED circuit (or anything else) then the PS and BL should come up when the system is plugged in while disconnected from the main board.

Why did I do this study?
I am also fixing a UN55D6050FXZA which seems to have a problem with the LED strips. My evidence is that the PS is cycling on/off, all the voltages are present when it is briefly in the on phase (verified with a scope), including the boosted voltage for the LEDs (390V, VF+ on 00424a board). Also it looks like the "dimmer MOSFET" Q9102 (00424a) which opens under control of IC9101S to pass the current coming back from the low end of the LED strip seems to be doing it's thing. There just isn't any current to pull.

I may verify this by bypassing Q9102 with a jumper to see if the backlights turn on. It is possible that Q9102 or its drive circuit are flakey and that is my problem. But given the shared experience, I think it is the strips.

John

[johnbinsc]

Re: Samsung UN55D6000SF - Success

Audioplus,
I may have need for the LED strips out of your UN55D6000 with the cracked panel. If you still have it, don't throw it away. The LED strips are worth something!
John

[tw2005]

Re: Samsung UN55D6000SF - Success

Audioplus,
I have no idea why changing out the PS and Main board on your UN55D6000SF brought the backlight back to life. The only thing I can guess is that the "backlight failure detection" circuit on your new PS board is less sensitive, and you have a backlight LEDs are on the edge but not yet gone.

Did you try all combinations of PS with the "new" main board? I am curious if it ONLY works with both the "new" main and PS from the UN55D6050.

I have studied the schematic for the BN44-00428b power supply (available on this site and also electrotanya), which is very similar to the BN44-00424a power in the D6000 series TVs. The main difference is that the 00428b PS has 4 independently dimmable LED backlight supplies for the 4 quadrants, while the 00424a has only the single LED backlight circuit.

From my study, the cycling is because upon power on, the LED driver IC (IC9101S on the D6000) detects a no current failure in the LED backlight circuit, and raises it's "FLAG" output line. FLAG drives the "main power supply shutdown" circuit (see lower right corner of page 3 of the 00428b schematic, it is almost identical in the D6000, right down to the component labels), which then pulls PS-ON back low asserting the power supply back into standby mode (i.e. A5 stays on, B5, B13, Vamp, and Vdrv shut off). This same "main power supply shutdown circuit" can also be triggered on overvoltage on B5 and B13. Note that there is a timer in the shutdown circuit, such that once B13 collapses, the main supply to restart once CM859 (00424a) or CM861 (00424b) discharges through RM880 (both) to a level that allows QM853 to turn off and PS-ON to no longer be asserted low.

Note also that this power on/off cycling should happen on the 00424a power supply with it disconnected from the main board. If there was no problem with the backlight LED circuit (or anything else) then the PS and BL should come up when the system is plugged in while disconnected from the main board.

Why did I do this study?
I am also fixing a UN55D6050FXZA which seems to have a problem with the LED strips. My evidence is that the PS is cycling on/off, all the voltages are present when it is briefly in the on phase (verified with a scope), including the boosted voltage for the LEDs (390V, VF+ on 00424a board). Also it looks like the "dimmer MOSFET" Q9102 (00424a) which opens under control of IC9101S to pass the current coming back from the low end of the LED strip seems to be doing it's thing. There just isn't any current to pull.

I may verify this by bypassing Q9102 with a jumper to see if the backlights turn on. It is possible that Q9102 or its drive circuit are flakey and that is my problem. But given the shared experience, I think it is the strips.

John

I've got a 55D7000, it has the endless cycling on/off. originally it would shutdown after about an hour of running and then start clicking on/off with the SMART logo.

We replaced the PSU and no change, after reading what we could here, stripped the panel down and from what we could tell the strips were working, no burns or dead leds we could see.

Re-assembled the panel and now all we get is the endless clicking.

I'm not sure if we've stuffed something or not but now the top 25% may not be illuminating, I just can't tell.

Have you found a way to bypass the safety cct and force the leds to stay on.

If we disconnect the backlights it just does the endless clicking also. We found that was the case when we could get this to turn on that if the leds were disconnected it would just cycle.

We've kinda given up as a main board is closwe to$400 and nothing 2nd hand. I'm hanging onto hope that a cheap main appears or get some better fault finding ideas from you guys.

The PSU in this is a BN44-00428b

[tw2005]

Re: Samsung UN55D6000SF - Success

May have worked some of my issue. I think the led strip lead got pulled and not 100% conected. gave the lead a little pull and it sounded like it unclipped, now only 25% lit. probably why we ended up with the on/off. so I'll have to get into the panel again which I dread.
that'll probably put me back to how it was where it started and worked and then starts cycling.

Seems to imply backlight issue but if they're all lit, I reallly don't know what I'm looking for fault wise unless there'a way to bypass this cct to keep it latched on?

[mmartell]

Re: Samsung UN55D6000SF - Success

These leds can get flaky when they fail and become intermittent. Did you test each one with your meter in diode mode ? When you had it stripped did you run it long enough to see if it would shut off on its own ?