Samsung LE19R86BD interference at switch on

[johnboy183]

Hi
My latest project is my sisters Samsung 19" lcd TV which for months now has suffered the following problem. When switched on from cold the picture is covered with white "noise" dots and has several equally spaced vertical white lines down the screen. The speakers crackle incessantly with the noise.
If you switch off ( at either the set or the remote) and switch straight back on the fault has gone and the picture perfect and no speaker noise. If the set is left on the fault does not reappear even iof left on all day and all night and if you switch off when the set is fully warmed up and then back on the fault does not appear.
This is reproducible every time so is not an intermittent fault and is not unique as someone has posted a video on Youtube of the exact fault (google "Samsung LE19R86bd interference" to view it).
I have examined the set and there are no blown components visible, no bulged caps, no evident dry joints and the boards and components all seem to be high quality items. I have tried the hot air gun and the CO2 spray to see if either switches on or off the fault with no effect.
I have posted pics of the fault and then after switching back on to show the good picture. I would really appreciate it if anyone has an idea of what could possibly cause this as its a new one on me. Just to be pointed in the direction to look would be good
Regards
John

[comptek]

Re: Samsung LE19R86BD interference at switch on

take back cover off and heat the large metal shield for a few mins try and shield the heat with cardboard tube or something as you need to find out if its the caps failed under the shield (try not to heat anything else) in other words

shield is at the top of picture

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

Thanks Comptek. Did try to heat that plate but not in a shielded way. Will try again as you suggest.
The symptoms to me did not really suggest a bad cap but I never ceased to be amazed by what causes what !
Have you come across faults with this board/set yourself?
(maybe its the salt in the air in Geordieland!!)
many thanks
John

[ReeceyBurger123]

Re: Samsung LE19R86BD interference at switch on

Common faults with these boards: they are piles of junk lol. Give it a blast with heat and see if the symptoms improve.

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

Surprised to hear they are a junk board as it certainly looks to be a better build and better components than the average - but I am only an amateur repairer so i bow to your wider experience.
One further point to note with this fault. If you turn the set on from cold and the fault immediately appears every time you can then leave it switched on for hours with the fault and it stays exactly as that (ie it doesnt improve of its own accord as the set heats up). As soon as you switch off and back on (either with the remote, the set buttons or at the mains ) it immediately is magically (!!!) "cured" and will run for hours or days without the slightest symptom until next switched off and allowed to go cold!

These sets have the touch buttons (hold your finger in front of) for on/off and controls. Do these fault and could this board be involved?
John

[comptek]

Re: Samsung LE19R86BD interference at switch on

Thanks Comptek. Did try to heat that plate but not in a shielded way. Will try again as you suggest.
The symptoms to me did not really suggest a bad cap but I never ceased to be amazed by what causes what !
Have you come across faults with this board/set yourself?
(maybe its the salt in the air in Geordieland!!)
many thanks
John

yes its common on the bd series 2 or 3 smd caps go on them under the sheild they just dry out cos of the heat, so heat the shield up for a while heating will bring down the esr of the cap hence after a while it works as normal

lol nothing to do with the salty air either lol

[comptek]

Re: Samsung LE19R86BD interference at switch on

try the heting up first
and touch buttons will cause like vol going up and down channels changing or turning its self off

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

Well thank you gentlemen as I now have some progress! I tried the opposite of your suggestion which was to blow Freezer spray through the small holes in the plate whilst the tv was sitting with a good picture ( to try and mimic the components in there being cold as at start up). Lo and behold the fault came on exactly as it appears in the photos I posted and, more importantly, the fault remains on even when the freezer spray effect has gone.
I will now try the opposite by heating the same area of the plate whilst the fault is on and see if it goes off. If so then it looks as though some component ( probably the small caps as you say) are duff.
many thanks - I will keep you posted on progress and in the hope it also helps others.
John

[Alastair E]

Re: Samsung LE19R86BD interference at switch on

2 x 1000uF 10v caps under tinwork.

[ReeceyBurger123]

Re: Samsung LE19R86BD interference at switch on

2 x 1000uF 10v caps under tinwork.

You mean heatsink lol

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

Hi
Got the tinwork off but I dont see any caps marked as 1000uf 10v unless they are coded or I am looking at the wrong component? (ie I am looking at the smd aluminium electrolytics)
John

[vinceroger69]

Re: Samsung LE19R86BD interference at switch on

can you upload a picture of the capacitors inside the cover

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

I have reinstalled the board without the tinwork and spray freezed each cap in turn masking it from its neighbours. Only one cap reacted and this one gave the exact symptoms the TV had been showing. The interference remained until the set was eventually turned off. No other cap when sprayed produced any interference.
This aluminium electrolytic is marked 7iD 47 16V. Do I interpret that as a 47uf 16v cap or are these figures a manufacturers code?
Any thoughts welcome as I feel I am getting near a fix here!
John

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

Will try for a photo of the caps but they really are very small so not sure if my camera will catch them adequatelly

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

Here (hopefully) is a photo of the area under the tinplate cover. I have circled in red the capacitor that appears to be causing the fault. Any comments or identification of it welcomed.
Cheers
John

[comptek]

Re: Samsung LE19R86BD interference at switch on

certainly look like 47uf 16v to me

[ReeceyBurger123]

Re: Samsung LE19R86BD interference at switch on

Replace all in that area for increase relibilty

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

Replaced that cap. problem seemed as though it would be fixed then suddenly, with excellent picture showing the screen went into blocks of colour with lots of interference. Leaving it on it then suddenly went to normal but later reverted to the blocks of colour again. When switched off it would not then come back on at all. Now it will come on intermittently. Something weird with this fault I fear.
I have also noticed ( right from getting the set) than when it is on the standby red light that if you switch on then the red led flashes 5 times then stays on momentarily, the set then does its little bleep tone and the red led goes off and the picture comes on. I just assumed this was the normal start up routine but can anyone confirm that for me - or is the flashing an error code I was not recognising?
John

[johnboy183]

Re: Samsung LE19R86BD interference at switch on

Here is a photo of the screen break up into blocks.
Any thoughts?
John

[comptek]

Re: Samsung LE19R86BD interference at switch on

well if it wasnt doing it before it must be something you did maybe replace all the caps not s/h ones though, it may need eeprom reseting