T240 inverter and resistor get hot again

[Nol]

Hi, my T240 had the well know 2 seconds problem and I change the inverter.
But when I open the monitor I saw that the R301 has been very hot, it was burned under the resistor so I change that too and replaced by a 390K-5W resistor.





It has been so hot that even the trail at the backside came loose
Monitor works again and keep working for 2 days now but I smell something so open the monitor again and both inverter and resistor get very hot again.
Because they are very close to eachother I think it is the resistor that smell
Does anyone know what the problem can be ?

[attainteddragon]

Re: T240 inverter and resistor get hot again

i would check the resistance on the outputs of the transformer and also check the ceramic caps as well.

[Nol]

Re: T240 inverter and resistor get hot again

I check all resistors because there not so much
R101 = 35,8K
R103 = 4,5
R104 - 28,2
R105 = 72,3
F301 = 4,3
I don´t have tools to check caps but they look good

This is my board

[petehall347]

Re: T240 inverter and resistor get hot again

something drawing the current . turn down brightness first see what happens . put that resistor up off the board .

[Nol]

Re: T240 inverter and resistor get hot again

I turn down the brightness but that did not solve the heating, resistor and inverter still getting hot.
In the first time I solder the resistor in a higher position but that did not solve the heating problem.
Even that, I have not so much space so I could not get it higher then ±3mm otherwise the steel cover put it down.
My most important question is : is it not the lamps that take to much power ?
If that is not the problem then I can buy a new board

[petehall347]

Re: T240 inverter and resistor get hot again

whatever is after the resistor is drawing too much current . i dont have the schematic . maybe a shorted capacitor .

[Nol]

Re: T240 inverter and resistor get hot again

Maybe a wrong resistor
I measure the bad resistor as a 390K but after comparing 2 pictures it could be a 190K.
Maybe you can take a look ?

[R_J]

Re: T240 inverter and resistor get hot again

This may not be exact but should be close, its a BN44-00226C, IP-54155B
looks like it is a 390K

[Nol]

Re: T240 inverter and resistor get hot again

Thanks a lot, I don´t know if it depends which inverter (T301) is on-board ?
I have the TM10160

[R_J]

Re: T240 inverter and resistor get hot again

The schematic is slightly different, looks like its for a Samsung 2494lw,2494hs,2443bw
It could be that one of the small blue caps are bad or the the ccfl's are drawing more current than when new. The original resistor was still good but was over heating the board, could be just due to poor design and lots of use???

[Nol]

Re: T240 inverter and resistor get hot again

OK thanks again.
I think it could be too many thinks that heat-up the resistor and inverter even I think that the inverter will be extra warm when the CCFL´s are on but the resistor should be some kind of cold
This took me a week now to find out what is the problem and I have to make a decision.
I think I take the change to order a new board so that I know that the board is OK and keep an eye on the resistor and inverter.
Thank you all so far and I come back to you

[attainteddragon]

Re: T240 inverter and resistor get hot again

unfortunately if the ccfl's are the cause for the excessive heat, then a replacement board will end up having the same issue that you are having now.

[Nol]

Re: T240 inverter and resistor get hot again

Yes I know but I have to take that chance and if it happen again I have to change the CCFL´s too.
I have not check where to buy them but I believe they are not that expensive

[petehall347]

Re: T240 inverter and resistor get hot again

you could buy a cheap ccfl kit and see if it gets hot running the ones in the panel .

[Nol]

Re: T240 inverter and resistor get hot again

I just receive the new board but even it is the same type (IP-54155A) it is differend and my question is can I use this board ?
I see them a lot for the Samsung T240 but I am not sure if it will work properly

[attainteddragon]

Re: T240 inverter and resistor get hot again

if your connectors are the same, you should have no issues at all from what i can see.

[Nol]

Re: T240 inverter and resistor get hot again

Thank you I try it and let it know.

[Nol]

Re: T240 inverter and resistor get hot again

Since I order the new board I had the old board connected but I did not close the backside cover so it is open on the backside and it works fine and the smell is almost gone.
Inverter and resistor still get hot
Now I connect the new but different board and same problem came on, after ±2 seconds backlight goes off.
So I think the new different board does not work properly in my Samsung T240 and I contact the seller about it and I connect the old board again and again it work well

[attainteddragon]

Re: T240 inverter and resistor get hot again

pity you don't have some spare globes. i think that would be a great way to test it out.

i have seen the connection come loose on the ccfl itself. ideally you would have to strip it completely down, but not sure if you want to go that far yet.

[Nol]

Re: T240 inverter and resistor get hot again

Just an update, TV still works fine with the old board and it does not get so heat anymore
I still have the new board which is different because the seller don´t want it back but refund me the money, respect for this solution.
I think to keep it as it is with the original old board
What is your advice ?