Samsung​ BN44-00703B power supply (TV turns off / on)

[OleAlgo]

Hi guys! New around here

I have about 20 TVs that I got from a hotel.
The model is Samsung HG40ND690DB (Hospitality TV).

These TVs are all having the same issue (presumably), that they randomly after some time turn off (and then turn on again a second later).

I am not very good with electronics, so hoping for some guidance as to
where and how to diagnose which components of the power supply that might be failing. Don't have much else on hand than a multimeter and soldering iron.

No visible bulging on any of the capacitors.
Have tried this already:
- Replacing the 25v 1500uf capacitors with 35v 1500uf ones.
- Disconnect WiFi module

- How should I measure the 2/3/4 pin mosfets with multimeter in-curcit? I'm guessing that's something I should check.

- Is this a model with known failures?
- Which components should I continue to check (and how?)

Thank you!
Please see attached pictures of one of the power supply boards.

[vinceroger69]

Re: Samsung BN44-00703B power supply (TV turns off / on)

what mainboard is used in these tvs.

[lotas]

Re: Samsung BN44-00703B power supply (TV turns off / on)

If there are no swollen capacitors, then this does not mean anything that they are working, their capacitance decreases over time and ESR increases, they have both an open and a short circuit (and they look like new ones). If the Mosfet were faulty, then the power supply would not start at all.

[vinceroger69]

Re: Samsung BN44-00703B power supply (TV turns off / on)

maybe worth trying a factory reset on them too
https://www.factoryreset.tv/reset/samsung-hg40ed690db

[CapLeaker]

Re: Samsung BN44-00703B power supply (TV turns off / on)

Check if the TV really turns off fully like you pressed the off button and then pressed the on button again or is it just the back light cutting out for a second. Monitor the PSon pin and see what that does. I wonder if the problem is on the main board or not.

[nomoresonys]

Re: Samsung BN44-00703B power supply (TV turns off / on)

is odd, might be a firmware glitch, might try an update and or factory reset as suggested.

[nomoresonys]

Re: Samsung BN44-00703B power supply (TV turns off / on)

also check your solder joints over very closely, some examples of bad joints there: https://www.google.com/search?q=bad+...h=578&dpr=1.25

[fatcatbaz]

Re: Samsung BN44-00703B power supply (TV turns off / on)

I'm interested to see how this pans out for Ole.

I have a "trash picked" Samsung UE55ES8000UXXU. It has a great picture and it could be a really good TV. However when I first tried using it the menu would freeze.I needed to restart the TV to move further through the menu until it froze again. I then did a factory reset and it certainly improved the situation. the menu still froze occasionally but far less frequently. The main issue now is the same as Olly's TVs. It will randomly restart. Sometimes every 10 minutes or so, sometimes after 45 mins/1 hour. As an example when it has appeared stable, I have left it running with the sound muted. When I come back to the TV the same channel is on but now off mute.

Currently I don't have time to work on this TV, so I have not inspected the boards. I am thinking about trying to reload the software, just concerned that I might "brick it" during an unexpected power restart. Still, it was a freebie.

I'll update Ole if I make any progress. I'm also keen to see if Ole can resolve the issues with his TVs.

If anyone has seen this before or has any ideas let me know..

Cheers

Barry

[vinceroger69]

Re: Samsung BN44-00703B power supply (TV turns off / on)

I'm interested to see how this pans out for Ole.

I have a "trash picked" Samsung UE55ES8000UXXU. It has a great picture and it could be a really good TV. However when I first tried using it the menu would freeze.I needed to restart the TV to move further through the menu until it froze again. I then did a factory reset and it certainly improved the situation. the menu still froze occasionally but far less frequently. The main issue now is the same as Olly's TVs. It will randomly restart. Sometimes every 10 minutes or so, sometimes after 45 mins/1 hour. As an example when it has appeared stable, I have left it running with the sound muted. When I come back to the TV the same channel is on but now off mute.

Currently I don't have time to work on this TV, so I have not inspected the boards. I am thinking about trying to reload the software, just concerned that I might "brick it" during an unexpected power restart. Still, it was a freebie.

I'll update Ole if I make any progress. I'm also keen to see if Ole can resolve the issues with his TVs.

If anyone has seen this before or has any ideas let me know..

Cheers

Barry

Maybe start a new thread of your own, what power supply and mainboard numbers are used in this tv.

[fatcatbaz]

Re: Samsung BN44-00703B power supply (TV turns off / on)

Good shout. It'll be a little while, as I won't get to work on it for a week or so. interesting problems though..

[nomoresonys]

Re: Samsung BN44-00703B power supply (TV turns off / on)

if there's a feature that you don't have then skip that test part: try these in order, method always the same, simple shit first, just start with one tv and see how it goes, take out remote batteries, press all remote buttons several times, make sure batteries are new, retry, next unplug cable from button board on tv, retry with remote, next unplug wifi cable, retry, next heat up or cool down bga chip on mainboard, then retry, once heated or cooled try it right then DO NOT let it cool back down before you try it, do all those and report back.