SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

[coopa]

I was given a "broken" 65 inch SONY XBR-65X750D and I'm a sucker for a good project. I've only repaired one other TV in the past but I enjoy learning about the process. However, so far I'm striking out on this one.

The red light was blinking 5 times and the screen would not turn on. Substituting trial and error for experience I purchased replacement T-Con, Main and Power boards but none of them made any difference. Using the original boards, I disconnected the ribbon connectors going out of the T-Con one by one. With only the left disconnected (when looking at the back on the TV) I still get the 5 blinks. With only the right disconnected the TV boots. At first there was only sound but after a few days the picture on the connected side started working for no apparent reason.

So, is it safe to assume that there is a short circuit in the right panel PCB? Not sure what that board is called... y-board? When I disconnect the cable bridging the two portions of that PCB I still get 5 blinks, so I assume the short is in the left portion and is triggering some sort of self protection shut down. Yay/Nay? Any advice on how to further narrow down the short? I tried testing the resistance of the little capacitors. One seems to show no resistance, but the the equivalent on the opposite PCB (on the working side of the screen) showed the same value, so I'm not sure that's it (not that I know what I'm doing).

On the half working screen I was able to pull up the error diagnostics but I can't see the labels since they are on the non-working side

Thanks in advance for any advice.

[Diah]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

you did every things correct, unless one things you didn't or you you did but didn't mentioned it.. inspect the ribbon cable you disconnected under good loop if there burn shorted on one of the pins from both side..

if every things fine, then just use scotch type to hidden the first 3-4 pins on the effected ribbon cable to see the error where located at the self diagnostic

[budm]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

If the cables look OK, then check the resistance of the MLCC (Multi Layer Ceramic Capacitor) on the suspect bad side of the tab bonding board, see if any of the cap shows <100 Ohms or not. Notes: no cable between the T-CON and the tab bonding board in place when checking the resistance of the caps.

[coopa]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

Thank you both for the advice.

I tried taping the pins (first 3-4 and many other configurations) but no success.

Testing the MLCCs seems to be the answer. On the bad side there were about 8 of the same variety, spread across both tab bonding boards, that measured very low resistance and both sides had continuity to the ground test point (attached photo shows two of them). So, if I replace those, or have them replaced since I'm not confident about my micro soldering abilities, do you think it will be fixed, or could there be a short in the panel that caused them to fail and will do the same to any replacements? And if I do replace them myself, do I need to get the replacements from donor boards, or is there some what to tell what the specs are for these capacitors? Thanks!

[budm]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

Those two caps in circle look to be connected in parallel.
How many Ohms did you read?
Are you good enough to remove it one at a time?
Since they are filter caps, it can also mean that you can have bad IC on the brown flexible PCB, so removing the cap first will be the first thing to do.

[coopa]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

Yes, those two are in parallel but others are different. I attached photo showing all of them. I get between .04 and .09 Ohms for the ones on the bad side. On the good side they are all around 3,800 Ohms, as I recall.

Are you suggesting that I remove one cap at a time, checking each time to see if it makes a difference? If so, yes, I could have a go at that. And do I need to re-solder each one before going to the next? After going through all 8, if it doesn't help, should I then assume it's the flexible PCB and call it game over? Thanks.

[budm]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

Remove one at a time then check the resistance of the remaining to see if the low Ohm goes away, if not then remove the second cap, if the shorts is still there then you need to trace out where the connection goes to next.
MLCC failure mode is short circuit 90% of the time, I replace many many many MLCC due to shorts.

BTW, IC on the flexible PCB is called COF: Chip On Flex/ or Film.

[RDC55]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

You can sometimes identify or at least make the best choice of which component in a group of parallel components is shorted by using a good set of meter leads / probes and paying close attention to the reading. For example, if one reads .41 and the others read .48, .51, .47 ..... then suspect the lowest reading one (.41) and remove it first.

[coopa]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

Thank you everyone. I removed two MLCC from the tab bonding board and one of them was indeed shorted. I included a before and after photo of the bad part. The entire screen works now! Any suggestions on how to determine the correct capacitance/specs for the one that needs to be replaced? Unfortunately I don't have an LCR meter, and even if I were to measure the good one that was also removed how would I even know if they were the same specs to begin with? The board is an LG 6870S-2228A but I don't see any online to buy for parts.

[budm]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

Great! you can just measure the capacitance of the good one (your DMM does not have cap meter built-in?), I suspect it to be around 10 ~ 22uF 25 ~ 35V (you can measure the Voltage on the cap) for typical filter cap.

[coopa]

Re: SONY XBR-65X750D TV - 5 blinks, only boots with T-Con half disconnected

Bringing closure to this thread. I tested one of the good MLCC and found it to be 10uF. I ordered a replacement (plus a few extras for next time!), soldered it in, and everything is in good working order. Thank you all for your advice! I learned a lot and I'm happy to have saved one TV from the bone yard.