SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

[diif]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

No idea why I wrote LG, replace LG for Samsung.

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

No idea why I wrote LG, replace LG for Samsung.

and what of my other questions? how does 0v on a power supply test point say anything about a panel? im quite sure that point in question is meant to be the ground of that particular test point?


...panel fault on a tv this new... bad samsung!

i am still hoping its something on the panel boards i can repair but ive checked all the mlccs i can see for shorts and dont find any...

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

so i must have been working too late and tired because i made a mistake and was looking at the panel connector backwards. i was blocking pins 15 and 16 but counting from the other side! so... not the clock 3 and clock 5.
i made a new piece of pin blocking plastic and made it extra thin this time to only block one pin. turns out blocking pin 15 makes the tv stable but still no picture and still no higher panel voltages.
here is which pin it is on the MB side.
i trace it to that solder point where it goes to a via and then poof! who knows where it goes!??

same happens on the panel side of the connector. i have to run for now but ill be back to try stabbing in the dark to see where this pin15 goes on both the mb side or the pb side.

[diif]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

and what of my other questions? how does 0v on a power supply test point say anything about a panel? im quite sure that point in question is meant to be the ground of that particular test point?


...panel fault on a tv this new... bad samsung!

i am still hoping its something on the panel boards i can repair but ive checked all the mlccs i can see for shorts and dont find any...

If only there was a way we could visually confirm what is going on in that area.

It's poor consumer law/vendors you have over there. Some vendors sell their TVs with a 6 year warranty.

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

i have noticed after much painstaking tracing last night that pin 15 goes to the first panel board, and to the second and somewhere on the second board, pin 40 connects to it (pin 15 and pin 40 appear almost as dead short on the second board only) and pin 40 goes back to the mainboard. so there is like a loop between 15 and 40 that i think makes sure all the panel boards are connected and throws an error if not? or does this loop actually go into the panel itself to check something? should i see resistance between these 2 pins on the second board or is a short normal? hard to know without looking at another tv, or a schematic!

[alfatv]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

Did you try to look into service manual? No more schematics, but at least there are connector pinouts
https://www.electronica-pt.com/esque...2-uwl01-85139/

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

Did you try to look into service manual? No more schematics, but at least there are connector pinouts
https://www.electronica-pt.com/esque...2-uwl01-85139/

wow thanks! ill have a look. i guess i shoudnt assume there is NO useful information in there...just not very much. not like...schematics or anything! but yes connector pinout is helpful!!!

--- oh dang i looked more closely and this is actually not for my model of TV. i have the 8000F and this pdf is for the 7000F series

i believe this is the correct manual:
https://www.electronica-pt.com/esque...ileinfo/83227/

wow...and i come to this line in the service manual:
"When replacing Main Board, certain values needs to be manually input in Factory menu to complete the replacement."

this cant possibly be true can it? ive never had to enter any factory menu to swap a board!


dang...and reading even further down it shows a picture of the mainboard and it is NOT the mainboard i have in this tv. it shows 2 connectors for left and right side of panel. i WISH my mb had that!

man... and almost 99% of the manual is just filled with useless garbage....endless lists of electrical parts with no way of identifying where on the board they are. does anyone find a use for this crap? or do they just make it to laugh at us?

the pinouts would be useful.... if they were for my board!

the manual references chassis UWK00
the only thing i can find saying chassis on the tv is a sticker saying Y20 TU7K ... but i am getting nowhere with that search.

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

here is the ebay link to the replacement board that was purchased. i may have been hasty to order this one because he had another of the same boards listed but that listing actually shows a good picture displayed. this one shows a blank backlit screen like i get....but i only get that to be stable (no power cycle) if i block pin 15 or leave the second board disconnected!

https://www.ebay.com/itm/39418043975...rdt=true&rt=nc

ive asked the guy if he would let us do an exchange of parts... get the "known good picture" mainboard to work with instead of this possibly suspect one....

here is a link to the "good one"
https://www.ebay.com/itm/38503763832...&segname=11050

[Davi.p]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

Greetings? I see no one..

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

Greetings? I see no one..

I see dead tvs...

Here's a picture of what that pin 15 seems to do. I can't find out where it goes beyond this loop. It dispears via vias on both the mb and the panel boards

[Davi.p]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

No, i ment, you started the thread with no greetings, reading a big post is a bit challenging, a sign of thanksgiving or friendness does not hurt. A favor must be return back a day

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

No, i ment, you started the thread with no greetings, reading a big post is a bit challenging, a sign of thanksgiving or friendness does not hurt. A favor must be return back a day

i was not aware i was being rude in the way i started my thread...

rest assured i have the warmest feelings in my heart for anyone on this forum, especially those who take the time to post. we are all in this together are we not? and i feel i have shown my appreciation numerous times by being an active member of the forum, trying to help on other posts where i have something to add, and of course thanking anyone along to way who tries to help!

GREETINGS, EARTHLINGS!!!
ALOHA FROM HILO, HAWAII

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

after thinking about it for a while, i really cant say i know anything about that circuit ive been tracing that goes out on pin15 and comes back in on the last pin (i labeled it 80 but it was just a guess)

for one thing, i dont know that it "goes out" on 15 and "comes back" on pin 80. i dont know the way to tell if it isnt the other way around in fact.
also i dont know if this circuit is merely a single uninhibited wire that when connected, simply tells some part of the mainboard that both panel boards are connected.
essentially i dont know whether i should expect to see some kind of resistance on that line, or not, under normal conditions.

all i do know is that blocking this line, stops all the other high voltages being created. and thus stops the power cycling. basically giving the same result as if the second panel board were not connected. which maybe means theres nothing wrong with this line, its just doing its job.

i do see a voltage of 3.22 volts on this line (on both pin 15 and "80") that is there and then drops out when the tv power cycles. ive tried to find on the mainboard where this 3.22v comes from but i cant see it anywhere else on the board
really getting hamstringed here in my quest for knowledge by a lack of a schematic or pinout diagram. i feel the only way is to possibly look at schematics and pinouts of "similar" samsung tv's and try to make some educated guesses... definitely over my head at this point, but if you're trying to learn something, you should be excited by what you dont know yet, and i am! just want to know more!

a pinout of these connectors might be helpful if i could decipher the pin names to something meaningful. I would love to test and trace each one of these pins but with so many there in such a tight spot, i dont see how to do that without driving myself insane.

[Davi.p]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

Ok, you can be the most correct man in the world but not everybody nows you, a little advice, never forget at least a tiny "Hi, " in the beginning. Now the tv, sorry read very fast all long thread because reading the first post it's almost clear to me it's the frequent common problem of the panel's boards, almost surely a bad condenser, the odd thing is you don't see a cold short, but we can make it explicit, much probably it's the AVDD/source tension rail that is at fault, so try to locate a test point for that rail, not so mandatory, on panel's boards the bigger condensers paralleled thogether are for that rail so, connect to one of them a bench psu at 15v starting low current, increasing one of the caps would go short and you will feel heat on it.. ah, for last the short is in the second board, so you can test it also alone with nothing connected..

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

Ok, you can be the most correct man in the world but not everybody nows you, a little advice, never forget at least a tiny "Hi, " in the beginning. Now the tv, sorry read very fast all long thread because reading the first post it's almost clear to me it's the frequent common problem of the panel's boards, almost surely a bad condenser, the odd thing is you don't see a cold short, but we can make it explicit, much probably it's the AVDD/source tension rail that is at fault, so try to locate a test point for that rail, not so mandatory, on panel's boards the bigger condensers paralleled thogether are for that rail so, connect to one of them a bench psu at 15v starting low current, increasing one of the caps would go short and you will feel heat on it.. ah, for last the short is in the second board, so you can test it also alone with nothing connected..

thank you. it sounds like you have more experience than me with this stuff. I will love to perform any other test i can manage on this TV just to learn more. I do have a bench PSU which i hope actually still works as its been sitting for a long time almost never being used... but this test point AVDD/source tension rail you speak of... i dont see any markings on the board for that. one of my posts here lists all the test points and their labels i was able to find and measure. is it one of those but the name is different?

[Davi.p]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

sorry my errors :

so mandatory, on panel's boards the bigger condensers

..biggest condensers..
therefore.. forget about testpoints, easier way, on a biggest size condenser apply the voltage as i have explained, increase current slowly, keep fingers on condensers..

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

sorry my errors :

..biggest condensers..
therefore.. forget about testpoints, easier way, on a biggest size condenser apply the voltage as i have explained, increase current slowly, keep fingers on condensers..

Is condenser another word for capacitor ?

[Davi.p]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

sorry, in italian the more used one is "condensatore" , much more than "capacitore" , yes it is the same, i will try to remember to use only "capacitor"..

[triplefour]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

sorry, in italian the more used one is "condensatore" , much more than "capacitore" , yes it is the same, i will try to remember to use only "capacitor"..

No need for apologies my friend! Thank you for helping me understand these circuits and working through a language barrier no less! Much respect!
I have dusted off my barely used bench power supply and found that it seems to work pretty well. It gives correct results with my tests using a 25 ohm resistor and ohms law. The only thing I am not sure of is that it can only go down to 2.5v max voltage even though I turn the knob all the way counter clockwise. And when I short out the leads and try to set max current I can only go down to 0.19A. When I put 25 ohm resistor and 2.5v I get 0.1a which is about right. And when I adust the voltage up I can get it to 0.19A at 4.5v which is about right. Resistor gets pretty hot then so I don't do that for long of course!
If I adjust the current knob then I can make it go even higher, and the voltage increases too and the resistor gets even hotter.


So I think I'm ready to try voltage injection for this case...but I think I should practice on some dead mother board or graphics card first maybe...and what if I need to inject less that 2.5v ? Don't cpu and gpu run off of 1v?

[Davi.p]

Re: SAMSUNG UN50TU8000F rebooting, backlight ok. No 12v to panel boards.

hi, there's no need now to inject on cpu or similar, instead in other situations yes, sometimes cpus fries..