Samsung le40a656a1f reaaaaaly slow poer up

[edugimeno]

Hi there!
A friend found a really good deal on a defective Samsung le40a656a1f tv set. So we needed to give it a try.
When you plug it to mains, the internal fan (weird that this TV has such a noisy fan!) starts running on and off all the time.

Meanwhile the front led blinks, but not at the same rate as the fan, like it's not really that the PS is turning off/on on both. And if you hit a button on the remote, the led blinks like it gets the code. This leads me to thinking that the main board is alive and has correct power

Then after 5-10 minutes you realize the backlight has come up, and the fan is now stable, but still no image or anything else.

After this, one or two times we have finally managed to see it fully power on, responding correctly to the remote, tuning channels, showing HDMI inputs with no problem, etc... I think one time we managed to have it 100% power up, we shut it off, and it turned back on with no problem after this, but when you let it sitting for days, back to same problem

Any idea on what to start with??

Thank you!!

[R_J]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Repair the standby circuit. likely a bad startup capacitor

[neilc6]

Re: Samsung le40a656a1f reaaaaaly slow poer up

A (2008) and B (2009) model years have lots of capacitor failures especially at this age. You will need to inspect the power supply board for bulged capacitors.

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Repair the standby circuit. likely a bad startup capacitor

You mean a standby section in the PS board?
Thanks

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

A (2008) and B (2009) model years have lots of capacitor failures especially at this age. You will need to inspect the power supply board for bulged capacitors.

Ok I will visually inspect caps and replace if needed
Thank you!

[R_J]

Re: Samsung le40a656a1f reaaaaaly slow poer up

You mean a standby section in the PS board?
Thanks

Post a picture of the board so we can see what you are working on. What is the power supply number? usually Bn44-00xxx

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

It's at my friend's house. My neighbor. I will check it tomorrow

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Ok, we got some advance here.
I found 2 large caps by the output stages of the PS that were clearly dried out. 1000uF 25v. Just replaced the,

Reassembled PS in place.

Powered on. It fired up instantly, as it should be. Plugged antena cable in and tried to watch some channels. Seemed to work fine until...

...

Then after 1-2mins working, the image started jumping up/down, most image was like frozen at the bottom while changing at the top, then back to ok, then back to jumping.....

Tried with HDMI inputs and same effect as with tuner

I am sharing a video here. Should I try to replace all the other surrounding caps? Or maybe anyone has another suggestion after wathing its effect?

Thanks in advance!!
Edu

[nomoresonys]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Sure switch out those other caps, can't hurt any, it could be a bad tab bond but no sense tearing it down if it might just be a bad capacitor.

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Ok, definitely wont hurt to do so. Im attaching a pic of the PS board. There are some medium size caps around the (already) swapped ones (pic taken before swapping), but there are also some other smaller caps farther away.
Should I care for those too?

Thanks

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Sure switch out those other caps, can't hurt any, it could be a bad tab bond but no sense tearing it down if it might just be a bad capacitor.

BTW What do you mean with a bad tab bond?
Thanks

[nomoresonys]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Not a bad idea to change all those electrolytic caps, just for good measure but I would for sure change those 7 right there.

[nomoresonys]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Changed out 5 bad bulging caps on my old 2008 sammy, it still acts up at times, thinking I should have changed them all.

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Not a bad idea to change all those electrolytic caps, just for good measure but I would for sure change those 7 right there.

Ok With "seven" you mean those together in the top right corner? But not the other spare and smaller ones at other areas of the board right?

If you look closely the bigger ones in that group of 7 are bulging and after the pic was taken, they were replaced. I would still have to replace the other 5.

Thanks

[nomoresonys]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Yes, you may be fine just changing those 2 but electrolytics life expectancy is 10 years even tho some have worked for 50 years or more, it's definitely the aluminum electrolytic caps that go first, I would just change those out those other 5 and see how it acts.

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Ok I went ahead and swapped all caps on the PS board
Not sure if I touched something else but now the effect happens immediately right after turning it on
And now it's worse. I can now barely see 1 stuck horizontal line in the middle and some 3-4 dancing line above

Video link
Any idea on what to look at??

[nomoresonys]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Could be a panel issue, with tv unplugged from power, connect only one side at a time between the tcon and panel, power tv up, see if you have a good display on half the screen, do both sides, report results.

[edugimeno]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Ok I will check that today. If that's the case then it's not serviceable?
Also someone mentioned redoing the tab bond, is this related to what you mention?

Thanks

[nomoresonys]

Re: Samsung le40a656a1f reaaaaaly slow poer up

Could be, there are workarounds, some call m temporary fixes but they can last a long time, "tab bond shimming" and the "tape-cutoff" are two pretty easy to do methods that work quite a bit, then there's some that are more complicated that I don't bother with unless I really feel energetic, my 20/20 vision is long gone, unfortunately.

[nomoresonys]

Re: Samsung le40a656a1f reaaaaaly slow poer up

There's a ton of videos on youtube of all the different methods, some very smart people posting there and one or two that don't know what they're doing of course. The good thing is there's usually several videos about the same subject to compare to.