Samsung LN52A550 - clicking. Eeprom or something else?

[aaronwt6]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Thanks for the repair feedback, I am trying to keep track as to how many fixes are done with replacing the caps (47uf 10V POLYMER TANTALUM) C102, C131.
https://www.badcaps.net/forum/showpo...&postcount=129

What I hate to think of is the stack of these boards (ones based of the BN41-00975B layout) that I've tossed in the past with this same issue. I'm certain it's at least a dozen or more. Another thing I've found with this board series is that as you can test nearly every one of them in any of the TVs that they go in. Basically, if you have say the LN40A550, you can test any BN41-00975B based board in it as long as all the jacks match (some have different variations of the T-con cable connector).

Sorry to get off topic but just wanted to add that info. Oh, and for reference; these are the capacitors I used for the fix:

http://www.mouser.com/Search/Product...67-10TPE47MAZB

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

I've located a schematic of a very similar board (from LN46A530) which shows two 10uF/10v caps in parallel on IC101 pin 2 (C138 and C102) and one 10uF/10v cap (C131) on IC102 pin 2. IC101 and IC102 are the same as the board we're discussing.

It also shows the caps I'm looking for (C516-C18). They indeed go to the Flash memory chip.

[CapLeaker]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

can you post it?

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Here it is.

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

What I hate to think of is the stack of these boards (ones based of the BN41-00975B layout) that I've tossed in the past with this same issue. I'm certain it's at least a dozen or more. Another thing I've found with this board series is that as you can test nearly every one of them in any of the TVs that they go in. Basically, if you have say the LN40A550, you can test any BN41-00975B based board in it as long as all the jacks match (some have different variations of the T-con cable connector).

Sorry to get off topic but just wanted to add that info. Oh, and for reference; these are the capacitors I used for the fix:

http://www.mouser.com/Search/Product...67-10TPE47MAZB

Thanks for the cap info.

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

I've located a schematic of a very similar board (from LN46A530) which shows two 10uF/10v caps in parallel on IC101 pin 2 (C138 and C102) and one 10uF/10v cap (C131) on IC102 pin 2. IC101 and IC102 are the same as the board we're discussing.

It also shows the caps I'm looking for (C516-C18). They indeed go to the Flash memory chip.

So in the A550 series they use 47uF + 0.1 MLCC instead of two 10uF.

[CapLeaker]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Here it is.

thanks!

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Another fix with confirmed bad cap on SAMSUNG main board.
https://www.badcaps.net/forum/showth...362#post518362

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Changing the caps did not fix my board. When the board is cool, it won't start unless I apply heat in the area or right on Q500. Once it starts, it will restart every time, unless I let it sit and "cool" off.

Along with C102 and C131, I've replaced Q500 and the Caps right above it (C516-518) with no success. At this point I'm wondering if there's a break in one of the inner layer traces under Q500.

Still stumped!!

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Can I see the picture in the area of Q500? Also can you do spot cooling?

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Sorry it's rotated 90 degrees. This is along the top side of the board, to the left of the ribbon cable and just above the metal can over the CPU.

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

It looks like it has something related to that ATMEL IC next to it, may be look up what the ATMEL IC is?
ATMEL 806? I cannot read the numbers.
BTW I use adjustable soldering Iron and set to low setting for pinpoint heating of the component.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

That Atmel IC is the main NVM IC204 24C256. I've swapped that with no success (and performed a factory reset after swapping the chip).
I do have freeze spray and that's I've been using to cool it into non-working mode. Then, as you say, using a soldering iron tip, heat the pcb around Q500.

[CapLeaker]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

looks like atmel 306 to me on the pic.

Something else... did you check those through holes jet?


Shoot.. clicked on the wrong doc.

[CapLeaker]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Lets try that again. 24C256 is an EEPROM. So usually these things work or not. Never had one fail of these yet. This is the correct file.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Yes, the AT24C256BN is the correct part. I have a good microscope and I've checked the via's and don't see anything unusual. Is there some other way to check them?

[CapLeaker]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Yes, by taking them off and put it in an EEprom reader.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

I'm not sure what you mean. I don't believe the EEPROM is bad since the set boots up when its "warm". I've also replaced this chip with no change in the failure mode.

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

You may want to check the signals at Q500 and IC204

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

So I spent a good deal of time over the weekend probing every signal I could on this board with my scope and I do not see any one signal that is different when the board starts versus not starting. There's still that one area that I can cool/heat to control the board startup behavior.

I just can't find the signal that's causing the board to not start. All the data lines at the flash memory and NVM look good so I know the CPU is starting every time, but there's some signal that it's seeing that it doesn't like. I can consistently press the reset button and see the CPU coming out of reset. All of the voltages (that I could find) appear to be normal.

I think at this point, as much as I hate to, I'm going replace the board. It kills me to think there's one signal that if I could find it, I could jumper around the bad spot in the board and make it work.
Thank you all for your help.