Samsung LN40D630/BN96-19438A main board noise

[Plane Nuts]

Happy holidays to all,

Picked up a Samsung LN40D630 LED TV, when plugging in, it will cycle on and off, LED will flash 5 times, and loud static/crackling sound comes out from the speakers, and this includes the back light cycling also, Voltages verified on the power supply board and they are all normal. attached is the main board and images I see on occasion, and they shake at the same frequency as the noise. and it is not steady for every cycle, sound changes, image like in picture iis there, sometimes no image, and even came back to almost normal at one point. also note that there is no reaction to the controls (power volume etc) as soon as I pug it in after 10 seconds or so it will power up. I am suspecting a bad connection or component but unable to pinpoint where. Any Ideas on where to look, or to help isolate?

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

10 second to power on after several time reboot it sound to me glitch at SPI can you located if its owned SPI Flash on boards ?

[Plane Nuts]

Re: Samsung LN40D630/BN96-19438A main board noise

Hi Diah,

please expain 'can you located if its owned SPI Flash on boards ?'' are you saying to try and reflash the firmware?

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

Hi Diah,

please expain 'can you located if its owned SPI Flash on boards ?'' are you saying to try and reflash the firmware?

SPI Flash IC are with 8 Pins IC which it responsible of starting firmware and back light too... i cant tell from yours photo where it is.. the label print on it should include No 25

BTW did you disconnected the socket between main boards and power boards then turn it on.. to see if the back light will come on and stay stable on.

[Plane Nuts]

Re: Samsung LN40D630/BN96-19438A main board noise

See attached picture, Square is S24CSO and circle is 4256BRP, and yes if I unplug the Main board the back light will run, no problem, also as a test, Main Board was put in the freezer for an hour or two, and when I tried it after that, I got 5 blinking lights and nothing after that for about 5 minutes when at that point the noise started back (time for the board to go back to a decent temperature?)will have to track down a can of freeze spray, however being in a lockdown only essential services are open...

to add on to this, If I let it cycle enough times (gets up to a certain temperature?) the TV will finally turn on but with an issue with the image, see attached picture.

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

ST 4256BRP the one i am talking on. if the freeze did delay as you wrote then try the heat with hair dryer

[Plane Nuts]

Re: Samsung LN40D630/BN96-19438A main board noise

Diah, you were too quick to answer, see previous post I edit in a few more details.

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

Diah, you were too quick to answer, see previous post I edit in a few more details.

same to my thought... freeze delay it.. then heat bring it faster...
i dont think the issue at main boards.. try to heat the cold area cabs on power boards..

[Plane Nuts]

Re: Samsung LN40D630/BN96-19438A main board noise

I only froze the Main board as all the voltages on the power supply were good.

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

try to heat as i wrote.. its not enough only 12V you measure was okay for example... but the currents (watts) playing the roll

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

on such issue as you have.. the first things i will go ahead to replace all cabs on the feeding line at power boards cold area... the set very old.. and its SAMY.. the chance of the cabs ESR to remain in tact value less than 50%

[Plane Nuts]

Re: Samsung LN40D630/BN96-19438A main board noise

Diah,

What do you mean with the feeding line? and what do you think about the image issue that I attached in a previous post? being slightly off?

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

Diah,

What do you mean with the feeding line? and what do you think about the image issue that I attached in a previous post? being slightly off?

upload clear focused photo of yours power boards to remark my point on it..

the picture you got on screen was much clear than the first one you posted.. bad cabs can be issue too and because of the bad cabs can cause the glitch at the SPI we talked before by trying to turn on.. so the correct way of trouble shooting this issue are to start from power boards

[Plane Nuts]

Re: Samsung LN40D630/BN96-19438A main board noise

I have attached pictures of the Power Supply, I have also tried heating up the Main board with a heat gun and it will start working almost right away. I will try to narrow it down to a single component, I also noticed there is a mofset on the main board that has something, you can see just below and to the left of the circle identifying the SPI flash IC I have attached a close up.

[budm]

Re: Samsung LN40D630/BN96-19438A main board noise

I have attached pictures of the Power Supply, I have also tried heating up the Main board with a heat gun and it will start working almost right away. I will try to narrow it down to a single component, I also noticed there is a mofset on the main board that has something, you can see just below and to the left of the circle identifying the SPI flash IC I have attached a close up.

I would try heating the main board section by section to help locate the sensitive section.

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

there is a mofset on the main board that has something, you can see just below and to the left of the circle identifying the SPI flash IC I have attached a close up.

SPI Flash IC operated at 3.3V and less. power boards supply 5V. so you have on main boards DC to DC converter circuit to feed the SPI with this low voltage.

so start to check VCC on SPI Flash if its changed when you start the set from cold state.

[Plane Nuts]

Re: Samsung LN40D630/BN96-19438A main board noise

No change on VCC on SPI Flash it is at 3.3. I have been able to narrow down the issue to what is circled in the attached picture and a closeup of that area. I also noticed that Lx on IC204 is at 1.7V however this does not change weather the TV works or not. at the upper one IC 202 I get 3.3V, FB 0.8, comp 0.9, and EN 2.6.

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

are IC204 & IC202 same NO ? if yes can you write the No over here

[Diah]

Re: Samsung LN40D630/BN96-19438A main board noise

at other hand... you need to do test when the tv at cold sate by reduce load on the main boards then plug it on... start with panel disconnecting one ribbon at once.. maybe the panel pull over currents... this happened but hope its not your case

[Plane Nuts]

Re: Samsung LN40D630/BN96-19438A main board noise

IC204 and IC202 are both the same Z1031AI, I also noticed that putting my probe on the COMP pin gives varying results (from .8 to 1.7) and the screen will act up with interference lines and stay until it resets itself, possibly normal? due to what I can induce into it. and Although IC 204 seems to have odd value, it is not in the area Is affected by applying heat this area is between IC 202 and IC204