Samsung UE55H7080 black screen (sound is working)

[SMDFlea]

Re: Samsung UE55H7080 black screen (sound is working)

Anyone can report a spammer, if you click on the triangle road traffic sign looking thing under a username.

The spam post is deleted,user banned and Budm`s post with the spam link edited. Cheers diff

[diif]

Re: Samsung UE55H7080 black screen (sound is working)

Looks like the guy has nothing but posts to that website. Anyway to ban?

Anyone can report a spammer, if you click on the triangle road traffic sign looking thing under a username.

[ngth82]

Re: Samsung UE55H7080 black screen (sound is working)

Did you not read which the faulty board is? Or you are just trying to sell boards? Read post #44.

Looks like the guy has nothing but posts to that website. Anyway to ban?

[budm]

Re: Samsung UE55H7080 black screen (sound is working)

Buy a bn44-00715a directly, no need to repair it
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Did you not read which the faulty board is? Or you are just trying to sell boards? Read post #44.

[nomoresonys]

Re: Samsung UE55H7080 black screen (sound is working)

A good fact to remember at least for this particular model is a faulty tcon can keep the mainboard from sending the proper bl-on signal.

[nomoresonys]

Re: Samsung UE55H7080 black screen (sound is working)

Ok good job, you went a long mile, if I can find a low priced tcon and I have the symptoms, sound always present, no picture with torch test etc. I grab the tcon. I've also spent 20 hours testing this and that and chasing wild possibilities but was just a faulty tcon, sometimes if it looks walks and quacks like a duck, it's just a duck.

[Steradiant]

Re: Samsung UE55H7080 black screen (sound is working)

The last weeks I was really terribly busy. I had no time to check more on the T-CON board, hence, I decided to buy a new one (or let's better say a working one from another TV from ebay). The TV works again!!!

[Diah]

Re: Samsung UE55H7080 black screen (sound is working)

YOURS OP that this set was working at night and next day only sound..??? are you sure the set was yours for long time ?

BL come on when you disconnected MB from PSU or Dim socket from T-con doesn't mean BL are OK. because protection level at software was out .. disabled
hard ware protection on PSU cant detect fault of open LED- it response only for short. only software detection can do this and this is the case

first things you need to check visual by eyes all BL led going on by test.. if not and the sets belong to you long time.. change T-con. if you got this TV from some one then Panel fault or damaged

[budm]

Re: Samsung UE55H7080 black screen (sound is working)

OK, since you can get backlights to come on by disconnecting the EXT 1 (connector with 6 black wires) and having EXT 2, 3, and 4 connected, since T-CON board does not need EXT 1 to be in place for T-CON to work (because it is the control signal sender to control the backlights level) then you can leave EXT 1 out for now.
Next remove EXT3 then turn on the TV, the backights should be on and then observe what you see on the screen, then turn off the TV.
Next, put EXT3 back in place, then remove EXT4 and turn on the TV, the backlights should be on then observe what you see on the screen.

[budm]

Re: Samsung UE55H7080 black screen (sound is working)

Pictures provided by shopjimmy.
There are many test points on the T-CON, some may be under the heatsink too.

[budwich]

Re: Samsung UE55H7080 black screen (sound is working)

but honestly... I don't understand you. If you know where the voltage is at say board A / connect x, pin y. Put you one probe there, ensure there is NO power applied to the system else this could destroy your meter. Put your meter on resistance / short beep test mode. Take your other probe and go to board b (assuming it is connected in some form to A, you don't even have to know where or how it is connected). Use probe to see where the meter register a short / 0 resistance anywhere on board B... ALL those areas will be connected to the "reference point" of the other probe. IF you are "wise", you will find points that are readily accessible and safe to probe WHEN you do your next test for voltage. Thus you have now found a "safe" place to place your probe to check for voltage at points on the board... which you "complained" about that weren't easy to access.... that's because you are trying to access the point at / or near the connectors which the lines are very close.... be smarter and find points further away / near "touchable" components.

Once you do this you will be readily able to follow voltages thru the circuit without knowing EVERYTHING about the circuit out side of say, this a resistor, this is capacitor... etc. IF the voltage is on one side of component, and not on the other, then you have likely found the potential problem.... you can go from there.

Again hope you understand this. Further, once you follow voltages thru the board, you will likely come across other components that you can find spec sheets on or people on the forum know what happens if a voltage comes in but not out (depending on conditions). You will get there. Yes, a schematic is nice but it isn't totally necessary and lots here, "walk" thru circuits with little more than a meter and some eyes.

As for the new picture, it shows LOTS of voltage points.... and some which I do believe match those on the tcon... so a voltage at edge board needs to match one on the tcon.

Still further, most voltage points are not going to read 0 and be labelled... IF they do, that is a good place to start digging deeper. Further, IF a voltage point does read 0, then it is likely being grounded or the driving component is dead. Thus another test would be a resistance test (with power OFF) to see if those voltage labelled points are grounded / 0 resistance.

LASTLY... did you read what budm posted????

Really, who cares if YOU don't know what the voltages are supposed to be... that is why you are posting in the forum with a list showing the label and voltage reading.... the forum will then help you understand whether the voltage is good, bad or otherwise.

[Steradiant]

Re: Samsung UE55H7080 black screen (sound is working)

well you are either thinking too much or not enough. :-)

First when asked to "trace a circuit"... you don't need to have power to it.... in fact it is better not to have any. You use a "resistance based trace"... that is you put your probe at one point which can see or identify readily easily and then take the other probe and see "logically" which the circuit / cable run... etc might run.... hopefully your meter has a "tone feature" which gives you a beep when it detects a "short" which would means that the two points are electrically on the same "copper". From this, you can readily move around any board to find points which are connected and more readily accessable for probing if you need to do a future voltage measurement. Hopefully, this understandable.

Further, the picture that you provide DOES NOT show the edge boards that are along the bottom of the set that the tcon cables are connected to. Those edge boards also have labels and are highly likely to have potentially faulty components that cause voltage issues between the tcon and the panel. Hence the "hints" of where to look. Do some reading / searching on edge boards to see what you are looking for.

Thanks, it was absolutely understandable and I thought of this but honestly, I don't see where this should get me. I can follow a trace but don't know what the trace is all about or what voltage I should have there. For me only measurement points are meaningful, where I have at least a hint if they should be 0 or not.

I also opened the bottom now (pic attached) but again no meaningful labels for me. On the other hand, like already stated above, we think it shouldn't be a problem of the panel or the connection from the tcon to the panel because disconnecting the two cables to the panel didn't change a thing.

[budwich]

Re: Samsung UE55H7080 black screen (sound is working)

Of course not, would be nice though if they'd tell you "hey, this voltage needs to be xxx"



Also a no here, I am afraid that this is mounted on an IC with a heat-conductive paste and I don't have one at home at the moment.



Here pops again the question up how I can follow them. Without a circuit plan this is nearly impossible without removing the tcon board from the tv.

For the labeling of the connections from the tcon to the panel I'd have to remove the lower cover to get to the other side of the cable. Probably there are some pin namings?

I found the pin names of some of the pins of the ribbon cable from the main board to the tcon (see attachment). Would they help? They are called something like EVEN_TX, ODD_TX (probably some serial connection?). I found Panel_VCC which is always about 13V on the mainboard.

I can nicely measure them on the mainboard but on the tcon board it's hard to reach a proper point because measuring at the plug (terminal where the cable is plugged onto the board) is nearly impossible because the connections are so small.

Still my biggest problem is to find proper pin namings on the tcon board to deliver suitable information.

well you are either thinking too much or not enough. :-)

First when asked to "trace a circuit"... you don't need to have power to it.... in fact it is better not to have any. You use a "resistance based trace"... that is you put your probe at one point which can see or identify readily easily and then take the other probe and see "logically" which the circuit / cable run... etc might run.... hopefully your meter has a "tone feature" which gives you a beep when it detects a "short" which would means that the two points are electrically on the same "copper". From this, you can readily move around any board to find points which are connected and more readily accessable for probing if you need to do a future voltage measurement. Hopefully, this understandable.

Further, the picture that you provide DOES NOT show the edge boards that are along the bottom of the set that the tcon cables are connected to. Those edge boards also have labels and are highly likely to have potentially faulty components that cause voltage issues between the tcon and the panel. Hence the "hints" of where to look. Do some reading / searching on edge boards to see what you are looking for.

[budm]

Re: Samsung UE55H7080 black screen (sound is working)

I see test points on T-CON, I.E. 1.1V, 1.2V, 2.5V, 3.3V, HAVDD, HVIN,... and probably more under the heatsink.
Samsung BN95-01315A T-Con Board
https://www.shopjimmy.com/samsung-bn...con-board.htm#

[Steradiant]

Re: Samsung UE55H7080 black screen (sound is working)

hopefully you are not looking for VXXX where XXX is 12.0, 20.0, etc.... you are looking for things that start with "V" (of course, not VGAxx... which a video signal).

Of course not, would be nice though if they'd tell you "hey, this voltage needs to be xxx"

Further, you have looked under the plate / heat sink area?

Also a no here, I am afraid that this is mounted on an IC with a heat-conductive paste and I don't have one at home at the moment.

IF in doubt, do some tracing of any voltages coming on cables directly from the power suppy or main board that you already know about... follow these towards the outputs to cable areas to the panel. There are panel drive voltages there as BUDM suggested... they may not be EXACTLY labelled the same but close.

In addition, the tcon to panel cables terminate on bottom edge boards which also may have some labelling that may help.

Lastly, because you have sound for all your "test scenarios", indicates that the main board is NOT shutting down the system because of a "detectable fatal error" (eg. panel disconnected)... so to me, this points to a problem at the tcon and beyond... hence that should be your focus.

Here pops again the question up how I can follow them. Without a circuit plan this is nearly impossible without removing the tcon board from the tv.

For the labeling of the connections from the tcon to the panel I'd have to remove the lower cover to get to the other side of the cable. Probably there are some pin namings?

I found the pin names of some of the pins of the ribbon cable from the main board to the tcon (see attachment). Would they help? They are called something like EVEN_TX, ODD_TX (probably some serial connection?). I found Panel_VCC which is always about 13V on the mainboard.

I can nicely measure them on the mainboard but on the tcon board it's hard to reach a proper point because measuring at the plug (terminal where the cable is plugged onto the board) is nearly impossible because the connections are so small.

Still my biggest problem is to find proper pin namings on the tcon board to deliver suitable information.

[budwich]

Re: Samsung UE55H7080 black screen (sound is working)

hopefully you are not looking for VXXX where XXX is 12.0, 20.0, etc.... you are looking for things that start with "V" (of course, not VGAxx... which a video signal).
Further, you have looked under the plate / heat sink area?

IF in doubt, do some tracing of any voltages coming on cables directly from the power suppy or main board that you already know about... follow these towards the outputs to cable areas to the panel. There are panel drive voltages there as BUDM suggested... they may not be EXACTLY labelled the same but close.

In addition, the tcon to panel cables terminate on bottom edge boards which also may have some labelling that may help.

Lastly, because you have sound for all your "test scenarios", indicates that the main board is NOT shutting down the system because of a "detectable fatal error" (eg. panel disconnected)... so to me, this points to a problem at the tcon and beyond... hence that should be your focus.

[Steradiant]

Re: Samsung UE55H7080 black screen (sound is working)

that helps a bit. Again, you are doing more than was requested but not reporting enough.... in this case, you make no mention of what happens to the sound in the cases that you have now put forth.

Yes, I'm doing more test than stated because I thought it could be helpful (and if not, at least it shouldn't be a harm).

I brought the new cases up because of this request:

I do not understand you chart in the Backlights row.
You show ON (EX1), ON (EX2), OFF (EX3), OFF (EX4)
You have 4 connectors so what combination of the four connectors have to be to get the backlight on?

And sound is working for all test cases I've tried yet.

Further, your "4 cases" show differences for when the back light is supposed lit (you didn't actually state this... but the guess is the first two instances) versus when they are not lit... pdim differences.

Yes, which I already tried to note twice. And I've tried to state it more clear in the table attached above. And yes, the behavior of the backlight correlates with the P_DIM voltages. If they are 0V it is turned off, if they are around 3.5V it is lit. The voltage levels were only measured on the power supply board till now.

It would appear from this that the problem is at the tcon / panel since when you disconnect incoming "controls / powerings" to the tcon, the backlighting comes on but disconnecting some form of tcon to panel results in "nothing".

Look at the tcon for various voltage test points and do some measurements / label list... this will likely move you closer.

Exactly these are my observations till now. Like explained in my last post, I've already tried to find some pins / label lists on the tcon board but I found nothing which is really meaningful in my opinion. I hope it's somehow readable in the attachments but voltage levels at e.g. C215 won't mean much to you.

[budwich]

Re: Samsung UE55H7080 black screen (sound is working)

I'm sorry if it was unclear but that the backlight is working at all came up during the tests recommended here. I didn't know that when I was starting the thread.

I repeated the experiments and made a table of the results (see attachments). I always disconnected one cable at a time, so 3 were plugged, 1 was unplugged for this tests.



In a particular area of the tcon board? There are a lot of capacitors on there.



When disconnecting both ribbon cables which go to the panel (marked with Ex3 and Ex4 in this attachment) and keep the cables marked with Ex1 and Ex2 plugged, the screen stays black, hence the backlight stays off.
Where can I find VGH, VGL, ...? I can't find these writings on the tcon board.

that helps a bit. Again, you are doing more than was requested but not reporting enough.... in this case, you make no mention of what happens to the sound in the cases that you have now put forth.

Further, your "4 cases" show differences for when the back light is supposed lit (you didn't actually state this... but the guess is the first two instances) versus when they are not lit... pdim differences.

It would appear from this that the problem is at the tcon / panel since when you disconnect incoming "controls / powerings" to the tcon, the backlighting comes on but disconnecting some form of tcon to panel results in "nothing".

Look at the tcon for various voltage test points and do some measurements / label list... this will likely move you closer.

[Steradiant]

Re: Samsung UE55H7080 black screen (sound is working)

The sound and backlight rows belong to the experiments in the same column respectively. As I noted, for these tests I always disconnected one cable at a time. Hence, I got the backlight on steadily by either removing cable Ex1 or Ex2.

In a later text, I've also tried to disconnect two cables at a time, namely:
Ex1 and Ex2 unplugged; Ex3 and Ex4 plugged: Backlight goes on steadily, sound working
Ex1 and Ex2 plugged; Ex3 and Ex4 unplugged: Backlight stays off, sound working

[budm]

Re: Samsung UE55H7080 black screen (sound is working)

I do not understand you chart in the Backlights row.
You show ON (EX1), ON (EX2), OFF (EX3), OFF (EX4)
You have 4 connectors so what combination of the four connectors have to be to get the backlight on?