Samsung UE49KS7000SXXH - No standby light

[B0r1s]

Re: Samsung UE49KS7000SXXH - No standby light

Solder station arrived. Replaced all 4 diodes. Turned on tv without data cable, and picture showed. Tried few times..

After reattached back cover and data cable, I turned it again, and after few minutes same problem, tv turned itself off and no standby light.. It turned itself off while i was in plex app and it was loading plex content.

Tomorrow i will disassembly it again.

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

recheck those diodes, make sure they are ok.

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

make sure you didn't leave something unplugged and none of the connections are loose.

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

see if the voltages at connector are steady now, also check all solder joints on underside, examples of bad joints: https://www.google.com/search?q=bad+...ih=607&dpr=1.5

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

redo test of unhook cable from powerboard to mainboard, see if backlights come on and stay on.

[B0r1s]

Re: Samsung UE49KS7000SXXH - No standby light

make sure you didn't leave something unplugged and none of the connections are loose.

I rechecked diodes after i finished, readings were ok, and i was careful about polarity. And i checked cables few times also.. i will check standby voltage and diodes again tomorrow.

[B0r1s]

Re: Samsung UE49KS7000SXXH - No standby light

But i noticed again fast ticking noise while tv is in standby mode. When tv is on, ticking noise is not present. This noise can only be heard from very small distance, maybe 10 cm.. so i don't know if that noise was present before..

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

ok, do tests in post 24 and 25, if that checks out, maybe check the electrolytic caps right by the connector.

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

be sure to check ALL the solder joints, look them over very closely, add a little solder to any that even look a little suspect, be careful not to solder bridge anything.

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

was that ticking there before you replaced the diodes?

[B0r1s]

Re: Samsung UE49KS7000SXXH - No standby light

Yes i noticed ticking noise after i removed back cover for the first time..

I did have a bridge with the small solder spot, but i think i removed excess solder.. what are these solder spots that are placed around diodes, many small solder spots? They do not hold any components from the other side?

Also i forgot to mention. When i replaced diodes i checked standby voltage and reading were:
When in standby 9.55 (on board it says 7.5)
When tv is on 12.83 ( on board it says 11.8)
Maybe something useful, maybe not..

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

think those are the solders holding the heatsinks on, good rule to make sure those solders are in good shape too because they can also be a ground, do you get the steady backlights now, when you unhook the cable from powerboard to mainboard?

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

good rule is unplug tv from power whenever hooking and unhooking cables, then plug back into power after the unhook to avoid any errant surges or such things.

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

see if you still have the steady ticking with cable from powerboard to mainboard unhooked and power cord plugged in.

[B0r1s]

Re: Samsung UE49KS7000SXXH - No standby light

I just opened tv, and again two diodes are shorted (one of these two) just like before. So i guess something is causing that diode to fail? I get 0.0 reading on both ends. And standby voltage is unstable and around 4-5v just like before. In short everything is like when we started. Tried unhooking motherboard, same behavior, light comes for a second and go out.

What can be a culprit?

Also i noticed now, with bad diode, ticking noise is slower (pauses between ticks are longer) when voltage was good after i replaced diodes, ticking intervals were so much shorter.

Video where you can hear it.

https://youtu.be/lAduhjNtqCA

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

did you check all your new diodes before you put them in?

[B0r1s]

Re: Samsung UE49KS7000SXXH - No standby light

did you check all your new diodes before you put them in?

Yes, several times, outaide of circuit and in after i put it.. i tried tv few times and tested diodes again. Everything was ok till tv shut down itself. I know what diode was shorted before, i will take out replaced diode in that place, i think that diode is shorted again..

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

seems like the diodes should have worked, wonder if you got a bad batch, data sheet there for 520-560: https://cdn.badcaps-static.com/pdfs/...3cbdc28824.pdf

[nomoresonys]

Re: Samsung UE49KS7000SXXH - No standby light

and the resistors in that area are ok?

[B0r1s]

Re: Samsung UE49KS7000SXXH - No standby light

I just took out diode from position where last diode was shorted, and this one is also shorted.. other diodes are ok just like before. It is a bit strange that i got shorted diode again in the same spot.

Resistors? Which ones? I only see one that is nex to heatsink.