Problem with start-up Samsung 40LNA550

[Electronicjoe]

I have replaced all the main electrolytics on the power supply board, B44-00197A with Rubycon's. I did not replace the 2 large 100 mfd, 450 volt on the PFC Block, just the 47 mfd, 50 volt on the VCC line. I replaced 7 on the COLD side of the Standby and multi Block. Symptoms are negative picture with wrong colors on start-up. Shuts down and then restarts normally and runs for hours. Seems to be most common on first start up of the day.
I checked voltages while operating with no signal and found 12.82 for 13 volts and 5.1 for 5.3 volts. Standby 5.3 volts reads 5.1 volts when plugged in but off.
Any thoughts or helpful hints appreciated.
Joe

[selldoor]

Re: Problem with start-up Samsung 40LNA550

Were the new caps from a reputable seller? if from ebay may be fake.
Is the currrent problem the same problem as before you replaced the caps.
Try Preheating different parts gently with a hairdrier prior to switching on.
May help pnpoint a problem area.

[CapLeaker]

Re: Problem with start-up Samsung 40LNA550

A thread without clear pix is next to worthless...
However sounds like a main board problem of some sort. Unplug the LVDS cable on the main board and plug it in again (good measure) and recheck. You should be downloading the service manual for it and figure out how to get in the service menu. Check the screen options, maybe the correct panel has not been selected.

[Electronicjoe]

Re: Problem with start-up Samsung 40LNA550

I purchased new caps from Badcaps.net store and amother reputable supplier. I will try to post photos.
Joe

[Electronicjoe]

Re: Problem with start-up Samsung 40LNA550

I have taken some photos of the Power Supply and Main Board and will try to attach them here. Where can I get a schematic of the Main Board?
Symptoms sometimes includes sound screeching and negative picture with wrong colors, then shutdown followed by startup.
I am looking at a similar problem on a similar Samsung Main Board and am testing a suggestion by BudM concerning 2 caps on the main board.

[CapLeaker]

Re: Problem with start-up Samsung 40LNA550

I think you are on the right track following budm's suggestion on those 2 caps, since you mentioned screeching audio and turn off...

[Electronicjoe]

Re: Problem with start-up Samsung 40LNA550

Thanks to CapLeaker and BudM. I will update this thread if his suggestion clears the problem.
Joe

[budm]

Re: Problem with start-up Samsung 40LNA550

So other people will have the link to my post:
https://www.badcaps.net/forum/showpo...&postcount=129
https://www.badcaps.net/forum/showpo...&postcount=128
So far I am able to use 100uF 10~16V low ESR in parallel with C102 to verify that the problem is solved before installing the new cap. So far so good. You can try leaving that temporary cap in place too to see how long it will last, I am doing that on the another 46" just to see what will happen months from now.

[Electronicjoe]

Re: Problem with start-up Samsung 40LNA550

Thanks for your help on this budm.
Joe