Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

[budm]

Fixed this one in October 2015, it uses those NEC-TONKIN caps on the main board like other Samsungs that have bad C102.
This main board does not have the C102 but has lots of the NEC-TONKIN NERAS7 (47uF 10V Tantalum) so I decided to replaced all of them and have been keeping in touch with the owner and the TV is still working fine as of today so I make this thread for future ref.

[braxton]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

Thanks for the update budm!
I did a quick test on my LN46A650 with power cycling problems by soldering in 6 X 100uF 25V electrolytic caps in parallel to the existing 6 NEC-TONKINS I could find on the upper side of the main board and so far so good- unit is working fine with no glitches or restarts!
Will test for longer and update if I notice any problems.

[budm]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

I did the same using lytics 100Uf 25V low ESR for testing first (same thing when I work on main board with C102 cap) to verify.

[CapLeaker]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

thanks for the update! I was actually wondering about that the other day...

[braxton]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

So unfortunately my problem came back. I've attached some pics of the issue I am having. First the picture starts out fine. At some point I get a few interference lines followed by a screen freakout with colors and lines and then the set reboots (never any squealing sound though). It may be fine for a bit after reboot or it may get a garbled pic and reboot again...

I might try removing the Tonkin caps and just using the electrolytics since the old caps may be developing shorts or doing other weird things.

Anything else I should be looking at? T-con? bad panel?

[budm]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

Did you use low ESR caps or generic cap?
You might as well get the rant caps from Digikey.

[braxton]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

Did you use low ESR caps or generic cap?
You might as well get the rant caps from Digikey.

I think they are Velleman (made in europe) generic caps.

[braxton]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

I think it is also worth mentioning that in my case, if I unplug the LVDS cable going into the t-con (but leave all other cables connected), the set will stay on indefinitely and will not reboot. Backlights stay on, but no image on screen since T-con is unplugged.

Does this rule out the main board and suggest a T-con or panel issue, or could the main board still be suspect?

[braxton]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

Another observation is that when the 4 ribbon cables going from the tcon to the lcd panel driver boards are removed but all other cables are plugged in, the set still power cycles, ruling out the lcd panel itself.

I think everything is pointing towards the T-con or the ribbon cable from the t-con to the main board, but most likely not the cable. It's just strange that the problem is sporadic. Maybe solder cracks or tin whiskers, but heating the board with a heatgun has no effect. Might try putting the tcon in the oven for a nice baking.

[braxton]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

what about the T-con caps at C120 and C2747 ect- see pic? They have 100 and A86 written on them. Anyone know their value?

[budm]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

100uF 10VDC, PANASONIC PTE series.

[braxton]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

100uF 10VDC, PANASONIC PTE series.

Thanks! Since they are Panasonic they are likely OK. I wish I knew what was causing the sporadic reboot but I'm pretty sure it has something to do with the T-con. Happening more often now too. T-con for this model is hard to find and expensive, so hoping it might be repairable.

[nomoresonys]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

Ever sort it out??

[freakaftr8]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

I know this problem it is a tcon board issue. There are 2 ram modules right above the main processor on the tcon that need to be re flowed with heat. The easiest way to find out would be to pull the metal cover off the tcon and heat up those 2 ram chips.

[nomoresonys]

Re: Samsung LN52A650A Power cycling, squeal NEC-TONKIN caps

Thanks Freakaftr8, it's so annoying when they just stop, unless they're in a coma lol, what's so hard about a small followup, referring to braxtons problem.