Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Let me stress on "this time".
I have had bad experience with electronic repair services both official and not official.
The quote for the repair of this TV by an official service was ridiculous. 400 euro for the panel and about 75-100 euro labor. That is more than what the TV was bought 4 years ago.
Had one JVC which was diagnosed with bad main board. Turned out to be a dead LED strip (one LED was shorted and one was opened) Quote by the repair shop...
dronerat
Member
Last Activity: 12-08-2022, 05:51 AM
Joined: 11-28-2019
Location: Sofia
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
I don't see the logic here because that way the capacitor will have both it's pads grounded. You can see the small trace between the resistor and the capacitor. I also managed to lose the resistor.
Nevertheless currently I have managed to fix the set using the "tape cutoff" method and it is working for 4 hours straight with occasional checks if it will start after powering off. Not really sure how long it will last, but that will do for now. If it dies again it will be sold...Last edited by dronerat; 06-03-2020, 06:51 AM.Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Turns out it was the resistor to the left of the capacitor that was causing the short. Removed it, the short is gone but the problem still persists. The TV started twice after that and I have not seen any artifacts/distortions of the picture.
Will get some clear tape to try and cut off some signals....Last edited by dronerat; 06-03-2020, 01:45 AM.Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Sure enough I have missed one on the buffer boards... Here is the little bugger on the most right point of the right buffer board. It is dead shorted. Here is a picture. It is circled in red.
Now I am not sure what will happen if i remove it and start the set without that capacitor. Or what is the value of this capacitor if I try to find a replacement.
I need to get some tape and try that first. At least now I know which ribbon cable I should try
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Last edited by dronerat; 06-02-2020, 10:11 AM.Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
I will start with that. I don't know with which ribbon cable to start, but I will give both a try...
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
I have checked probably all of the capacitors on the driver boards and did not find any shorted ones.
Probably this evening I will disassemble the set and remove all of the plastic panels around the display to see if there are more things that I can measure....Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
I was not able to find a third LED on the T-Con board...Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
I have two T-Cons and they respond the same.
I will try the tape cutoff method.
I will also remove the heatsink on one of the T-Con boards to look for a third LED....Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
The one circled with green stays constantly on while the other one circled in red lights up for a second and then goes off when the TV is not working correct. When the TV is working it is constantly ON....Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
No third LED on the T-Con only two....Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
That is a thing I will definitely try. This evening I will try to remove the plastic covers from the panel, see if there are more boards there and measure them as well.
I am even thinking of checking the LED strips if I manage to get to them without cracking the screen and also check them. The strange thing is that the panel works perfect until the TV is powered off, so I still have a little bit of doubt that the panel is bad.
Also when either of the ribbon cables going...Last edited by dronerat; 06-02-2020, 05:28 AM.Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Ok now I am really fed up with this TV.
Since my last post I bought a freezing spray and tried to freeze the EEPROM with no success.
Then resorted to buying another mainboard together with the ribbon cable that connects the mainboard with the T-Con.
The TV powered up fine. Managed to set the settings etc.
And left it working for about an hour or two happy that it seemed to resolve the issue.
Turned the TV off and the problem is back again....
...Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Ok so changing the power supply gave me hope for just a bit, but it died quickly.
Swapped the PSU boards, and the TV began starting normally more often than before. I said: Well... I'll put it in the bedroom while I get capacitors or something to troubleshoot the board more, but after 2-3 hours of working i powered off the TV and was not able to power it back on since then.
I will get one of these compressed air cans in order to freeze the EEPROM to see if that helps.
...Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Today I ordered a replacement PSU from a TV with a broken screen (at least the seller says that). I should receive it in 1-2 days. Hope it fixes the problem. Will keep you updated.
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Interesting a similar thread started a few days ago [url]https://www.badcaps.net/forum/showthread.php?t=82618&highlight=fail_count[/url] with a similar looking PSU says that Fail Count is 0V.
And the user is having similar but far worse symptoms, but one of them is the TV coming on with backlight but without a picture.
Might give changing the PSU a try.Re: Samsung UE48JU6400W - back light... started a fewLeave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
I am really out of ideas. The only thing abnormal I see is the sizzling (not really sure how to describe it) coming from the power board. Visually there are no bad components, but I think it is possible to have voltage drops during startup that prevent the T-Con from starting.
I have measured the output voltage and it seems to raise during power on and not go from 9V to 12.8V directly, but this might be due to my crappy $5 multimeter.
I am really considering buying another power...Last edited by dronerat; 05-18-2020, 05:55 AM.Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Ok so I somehow managed to start the TV in service mode with the panel ON. Took a ton of pictures in the different menus just to be sure.
Now the fun thing begins. I connected EEPROM_SDA to EEPROM_GND and have some mixed results.
Now the panel starts 7/10 times, but I still have some of the runs not starting correcly.
I am starting to think that the PSU is acting up on me, because shorting the two signals changed the boot sequence which may have led to the T-Con starting...Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
I have looked through all the components on the board, but did not find IC7301. If you are referring to the main eeprom I think it is IC1101. It also has eeprom test points.
Im thinking of trying to connect EEPROM_SDA and EEPROM_GND or EEPROM_SDA and EEPROM_VCC and turn on the TV to see if it turns on. I will not disconnect the EEPROM_SDA and GND/VCC signals while the TV is so that I will not erase the eeprom.
As far as I read it should force the TV to turn on with default...Last edited by dronerat; 05-17-2020, 11:38 AM.Leave a comment:
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
Did the factory reset. After the TV restarted the panel stopped working again
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Re: Samsung UE48JU6400W - back light on, sound on, sometimes picture.
From the TV menu or from the Service menu?...Leave a comment:
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