Samsung UN82MU800DFXZA - Black screen+Sound works

[budwich]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

Could you help me explain how I would test the voltage going to the board and leaving the board? What settings I should set my multimeter to? I understand you don't test at the power, but at the points next the power as they match up to the total connections. Where the arrow is pointing is where I would test, right?

you are looking at the wrong connector area. There is one cable running from the power board to the tcon. That is the one of interest. I believe the labeling associated with the connector is on the power board.

Does this set have / use a "one connect box"?

[Island_Stylin]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

you are looking at the wrong connector area. There is one cable running from the power board to the tcon. That is the one of interest. I believe the labeling associated with the connector is on the power board.

Does this set have / use a "one connect box"?

Yes, it actually does use the "one connect box." Think that could be a possible culprit?

Attaching images of boards.

Do I need to take off the PSU and look at the other side to figure out the readings I should be receiving?

[budwich]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

disconnect the one connect box and turn on the tv.... what happens to the display?

[Island_Stylin]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

disconnect the one connect box and turn on the tv.... what happens to the display?

We've actually already had the onebox disconnected while tinkering this whole time. Nothing changed besides the fact that we now can't find the source through the menu system (as we can't see anything on the tv).

When the onebox was initially connected and everything was plugged in we were able to hear sound, but no picture. Since disconnecting it we haven't been able to get to a source where we can hear sound again.

[budwich]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

OK... but there is usually a "warning screen" that is displayed to connect the one connect box. That was part of the "test". So you are saying you get no warning. As suggested, look at the voltages / signals on the small connector coming from the power supply and measure those with the set at "standby / plugged in" and again with the power button depressed. Perhaps that will provide further clues to the problem area.

[Island_Stylin]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

OK... but there is usually a "warning screen" that is displayed to connect the one connect box. That was part of the "test". So you are saying you get no warning. As suggested, look at the voltages / signals on the small connector coming from the power supply and measure those with the set at "standby / plugged in" and again with the power button depressed. Perhaps that will provide further clues to the problem area.

Yes, no warning screen appeared. You and others have mentioned testing the voltage coming off the board. I tried to display which areas I should test, but I am unsure where you read where those voltage numbers are on the board?

Also I am unsure what the settings should be on the multimeter to get the proper setting. I included a few close ups of the board for you to look at above in this thread.

[budwich]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

I indicated to you which connector.... the one cabled to the power board. I then said look on the power board for the labels on the connector there. You are reading voltage with a multimeter. One probe (black) on a ground / chassis point and the other on the point of interest as labeled. Post the results.

[Island_Stylin]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

I indicated to you which connector.... the one cabled to the power board. I then said look on the power board for the labels on the connector there. You are reading voltage with a multimeter. One probe (black) on a ground / chassis point and the other on the point of interest as labeled. Post the results.

Please excuse my ignorance on the subject. Your instructions were clear. I initially misinterpreted what you were saying. Thank you for your continued guidance.

I have tested the PSU port in the picture with the TV off and on. This connects to the T-Con. The voltage read 12.82V on 5 of them. 4 were ground at 0. The last IF was at 3.5V

On the T-Con board I measured at each connection. The 7 from right to left read 12.78. The rest read 0. When disconnected from the Tcon board they read .90V

[Island_Stylin]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

Okay...I did some further testing. I tested the lower power connector going from the PSU to the main board. This was the lower power connector. I have put the readings on the picture attached below. When i touch what I believe is the ANA_DIM to the connector next to it the entire unit backlights dim.

The number 20 plug readings from RIGHT to LEFT : 0, 12.8, 12.8, 12.8, 12.8, 18.38, 18.38, 18.38, 0, 0.

Stranger yet. I turned off the tv. Unplugged the other cable from PSU (above the one I notated above) and while the tv was off the entire units backlights turned back on without me powering on the tv and the remote wouldn't turn it off. (probably a mistake not to unplug the tv when I did this. Standby power affected it?) I then unplugged the tv. Turned it back on and the TV backlights turned on bright and then turned more dim. This is new. They backlights have never been dim before when i turn the tv off and on. Now everytime they turn dim after the initial bright lights of the backlights. I either did something bad when I tested the unit or??? Front of screen no longer shows bright dark blue...now you can't see anything really...very very faint.

[nomoresonys]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

If you mean you unhooked cable from powerboard to mainboard and the backlights came on and stayed on, that's normal but you should not do it while tv is plugged into power as good practice, if while the cable was unhooked the backlights were steady that means the powerboard and backlight circuit are ok, so issue will be mainboard, tcon, panel or a cable or connection.

[budwich]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

Okay...I did some further testing. I tested the lower power connector going from the PSU to the main board. This was the lower power connector. I have put the readings on the picture attached below. When i touch what I believe is the ANA_DIM to the connector next to it the entire unit backlights dim.

The number 20 plug readings from RIGHT to LEFT : 0, 12.8, 12.8, 12.8, 12.8, 18.38, 18.38, 18.38, 0, 0.

Stranger yet. I turned off the tv. Unplugged the other cable from PSU (above the one I notated above) and while the tv was off the entire units backlights turned back on without me powering on the tv and the remote wouldn't turn it off. (probably a mistake not to unplug the tv when I did this. Standby power affected it?) I then unplugged the tv. Turned it back on and the TV backlights turned on bright and then turned more dim. This is new. They backlights have never been dim before when i turn the tv off and on. Now everytime they turn dim after the initial bright lights of the backlights. I either did something bad when I tested the unit or??? Front of screen no longer shows bright dark blue...now you can't see anything really...very very faint.

:-(... :-)
You should probably do a bit of internet reading on how to use a multi-meter (eg. youtube or otherwise)... or maybe read the manual for your meter :-) Of course, each meter is different and of course, the one that you are using is also somewhat different... :-( It is a general purpose meter... nothing wrong with that BUT then you need to understand what the scales are. In this particular case, you chose "unwisely" and used a scale for testing "batteries" not electronic circuits. There is a DC voltage scale for general use as identified in your picture. The problem with using the "battery scale" is that it likely is a "low impedance circuit" which the results in impacting the circuit under measurement. Hence, you got some things happening in the measured circuit that would normally not happen... maybe.

Anyway, it is unlikely that you damaged anything in the process... not withstanding "unplugging / plugging cables with power connected to the tv".

Note: the purpose of the tests was to provide some basis for possibly determining whether the tcon has the power to do its job as opposed to just "blindly guessing" that the tcon is bad. At this point, it would appear that the power supply is providing the necessary powerings (although I am not sure about the "IF3 pin"... it might refer to a Fuse point). Your further "tests" appear to show that the backlight is functional in some form. More digesting of the tests is needed.

"Some digestion".... your first picture shows your readings but it appears they are reverse, left and right... :-)

Further, as noted by nomoresonys, cable movements should not be done under power... NOTE: that means disconnected from the wall. A tv usually has "standby power" active (and maybe others) when plugged in regardless of whether it is turned on or off.

More digestion: your last "not sure how to test" picture. You test the same way but only worry about pins that are readily accessible with the cable plugged on. The one that is probably of most interest is the "fail count" but others should be measured.

[Diah]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

Now everytime they turn dim after the initial bright lights of the backlights. I either did something bad when I tested the unit or??? Front of screen no longer shows bright dark blue...now you can't see anything really...very very faint.

i would suggest you stop testing as you may cause more damage and the original fault as Nicks wrote.

put your One connect back.. and all cable back too.. take out the heat sink from yours Original T-CON and with hot air gun heat it well...

[budwich]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

:-) happy cooking

[nomoresonys]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

"i would suggest you stop testing as you may cause more damage"

[budm]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

https://www.badcaps.net/forum/attach...7&d=1593152508
Look at where the black probe of the meter is plugged into!

[Island_Stylin]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

Total mess up with the multimeter. Youtube school here I come.

In regards to causing more damage : We do not have anyone where I live that is able to repair these types of televisions unfortunately. I don't mind running further tests on it as if nothing works we will be forced with throwing it away unfortunately. I am hopeful that there are further tests I can run that will help diagnose the issue.

I will use a heat gun on the TConn board to see if that works. May I ask the temperature and how long you let that cook for usually?

Seeing as the main board and tconn board have been switched out for "new" ones, it would be a shame if those were the issue. I am able to return them by July 7th for a full refund though.

Definitely screwed up with unplugging the psu cable to main board without unplugging from the wall.
Nothing sparked, which is a good thing. Nothing looks burned out either. Though the LCD backpanel now turns on bright for a second and then goes to dim when I turn the tv on. An odd change from before where it would turn on bright and stay bright.

[nomoresonys]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

I didn't suggest you stop testing, just thought it was a FUNNY post.

[Island_Stylin]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

https://www.badcaps.net/forum/attach...7&d=1593152508
Look at where the black probe of the meter is plugged into!

Not in the COM port.

Boy, I wish I had a class on electronics when I was younger.

Assuming I would put to Vdc 20 for anything under 20volts. If its higher, go higher...

[Island_Stylin]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

I didn't suggest you stop testing, just thought it was a FUNNY post.

OH, i know you saw it as a joke! lol. I agree. It's already busted....what good would it be not to test at this point?

Thanks again for sticking with me on this new journey!

[budm]

Re: Samsung UN82MU800DFXZA - Black screen+Sound works

At this point for safety, you should plug the TV into the GFCI outlet to protect yourself.
At this point, if you disconnect the cable between main board and the power supply board and plug the TV into the AC outlet, do the backlighst come on right away and stay on as long as the TV is plugged into the AC outlet?