Samsung LN46B540

[plamenhr]

Hi,
I have an issue with my Samsung TV - it can't be turned on by the remote control.
I can turn it on using the power button on the TV but then the channel up/down buttons are not working and the volume up/down buttons are changing the input source.
The stand by LED is flickering when the TV is on.
The inverter board is model BN44-00265A.
No visible damage on the capacitors.
Any idea what can cause this issue?

[plamenhr]

I found the schema of BN44-00264A which is very close to mine.

[Davi.p]

PS board is not your issue obviously, if the set has soft touch controls then the buttons board can be faulty, or bad solder on a bga on the main board, or if present ruined software on the standby microcon

[plamenhr]

Hi Davi.p,
You were 100% right - the issue was caused by the buttons board, I disconnected it an everything is back to normal!
I didn't expect that board with so few elements can cause such issue.

[Davi.p]

Well, the board can be salvaged, remove one at a time, in order, first the DS (diode suppressor) then the ceramic caps (brown), one of those are leaking..

[lotas]

Well, the board can be salvaged, remove one at a time, in order, first the DS (diode suppressor) then the ceramic caps (brown), one of those are leaking..

The problem here is that the buttons are leaking, either replace them or spray them with Contact Cleaner aerosol and press them many times and the leak will disappear.

[Davi.p]

It"s a common fault the one i described, it is caused by static electricity in human hands..

[plamenhr]

Hi Davi.p,
Thank you for all the advices, really appreciated!

[cheeky2]

The problem here is that the buttons are leaking, either replace them or spray them with Contact Cleaner aerosol and press them many times and the leak will disappear.

It's certainly not static electricity that Davi.p suggests! It is not a touch sensitive board but a switch button board BN41-00989A As Lotas has stated it's the buttons leaking continuity. I have done this repair on this board many times before. You can carefully disassemble the buttons and clean them with WD40 or equivalent Contact Cleaner spray, I usually clean the contacts with wet and dry inside the switch and on the round contact inside. Be patient taking apart all of the contact switches with a small flat bladed screwdriver. If your not capable replace the BN41-00989A or just remove it from the connector!

[plamenhr]

Hi cheeky2,
Thanks for the advice, I will try to repair the board.

[Davi.p]

Cheeky2 your experience is welcome but it is not all the experience, i repeat my guess and continue to trust it.. i found failing mechanic buttons especially in monitors , where them are thorougly used instead of big remote controlled tv..

[lotas]

Cheeky2 your experience is welcome but it is not all the experience, i repeat my guess and continue to trust it.. i found failing mechanic buttons especially in monitors , where them are thorougly used instead of big remote controlled tv..

Buttons deteriorate (leakage appears) not because of frequent use, but because the silver-plated membrane and contact pad oxidize and begin to turn black, and this oxide begins to create resistance between the contacts inside the button, creating false positives!

[Davi.p]

A click micro button is a normally open contact, so the oxidation if present prevents the circuit closing at correct resistance, but button are not be pressed when faults occurs.. leakage for me could happen when curved plate shape degrades and touch the center pin when not pressed.. anyway i can only wait the user response now, but before dismantling buttons them can be tested with beep test of dmm, if test fails and you are sure about silver plating, board could be placed in a small food aluminum can with few water, baking soda and heat it without boiling for ten minutes, then wash it in distilled water..

[cheeky2]

Let me explain a little further the switches have when this fault occurs has a resistance within the switch ( call it leakage). The solution that I have found you need to physically clean contacts I use wet and dry sand paper first inside the switch (replace the switches if you wish however finding suitable dimensions for them can be tricky to find). As good measure I then use electrical contact cleaner inside the switch. Reassemble the switch and on to the next one. All of them must be done to prevent any reoccurrences.
I have found it is very tricky to determine which of the switches is faulty or partially short circuit with a meter. This is as a result of using voltage levels to turn on the relevant functions on the main board, this is achieved by putting different value resistors in line with the mechanical switches on the same common wires. The problem is the switches use common wires for signalling on so you don't know which switch or switches is faulty as you would be checking in parallel with the mechanical switches and resistors. So I always opt for the best approach is to clean them all, particularly if one has failed the others are likely to follow suit at some time.
The button assembly has plastic buttons in front of the unit as pictured so static is unlikely to play a part considering the physical dielectric of the plastic.
Good luck with the repair

[CapLeaker]

Had the same problem on my 52” version. Kids and their chocolate fingers did the same thing to my TV. I took the button board out and cleaned it with 99% IPA followed with deoxid. Worked perfect afterwards and is still working to date despite the TV being old now.

[nomoresonys]

Thanks CapLeaker, proves that sometimes they do just get sticky.

[CapLeaker]

Thanks CapLeaker, proves that sometimes they do just get sticky.

I am just not sure why this is. All I remember from 10 years ago that the problem was my power on and off button with the next button on top of that. It was so bad that the on off button was maybe working 1% of the time. It also took me a little bit to clean it up good and make it work 100% again. It’s been like 10 years now since this repair, but it is still working fine. I think I got this TV about 15 years ago? Time flies…

[nomoresonys]

I hear that, bought a Sharp Aquos LC32D43U new in 2007, that time sure did fly by, has worked for about 12 hours daily ever since as pc monitor. Never a problem, I just blow out any dust with a leaf blower about every 2 months, I think it will outlive me lol.

[plamenhr]

Thanks to everyone for the suggestions.
I used baking soda and white vinegar to clean buttons membranes and everything got back to normal.