lg 60ld550

[BCM_OC]

Re: lg 60ld550

Maybe try heating with a hairdryer a small section at a time on powerboard, see if it comes on or there's any change, can also heat mainboard and inverter boards and see if it comes on or changes any.

Well, I ended up taking your advice, and it worked!! When it came on I was like, "Son of a ..." Then I was like

Last night I ended up going over the power supply schematics, board traces, and my earlier test results. I realized that the mosfet on the power supply board that I thought was "shorted", would actually require removal for proper testing, and that it might be OK after all.

So, this morning I decided to give your idea a try. I kind of figured that I really didn't have all that much to lose, and an awful lot of people on YouTube seem to have found success by doing that to their LG TV's. It's really not my style of diagnosis, but then again, I'm a little out of my element with TV repair.

I ended up just using a heat gun on the tops of the two heatsinks above the graphics(?) chips only, and I only did it long enough to get the two heatsinks up to about 395 - 410 F for 4 or 5 minutes. I monitored it with an IR temp gun during and after, and connected it back up and tried it out once the temps got down to around 115 F or so.

I guess that this is a solder ball failure from the lead free solder cracking between the chip and the board. As Louis Rossman so expertly explains on YouTube, I'm thinking that this is just a temporary fix. I also wonder if this is how the board repair services on Ebay are "repairing" these boards.

However, since new main boards seem so hard to find, I think I might just try to "reflow" this board using the "best practices", and see what happens. My plan is to use some Amtech VS-213A-TF "No Clean" Tacky Flux and inject it under the two graphics chips as much as possible with the syringe needle tip before placing it in the oven at 400F for 10 - 12 minutes. Hopefully, that flux will help the balls reflow a little better and last a little longer.

Now I know it's the main board though, so thank you very much for that.

[nomoresonys]

Re: lg 60ld550

Well I was suggesting a test where you heat different parts of the boards for a minute to see if anything changes. Looks like yours was the bga problem tho, I think the heatgun method is better than the oven baking, there's a lot of things that get cooked that don't need to with the oven method. If you follow some of the pros advice on the right videos it may last quite a while. There's a good one on youtube, can't recall which one exactly but he explains it well, need to get it slowly up to temp and bring it back down slowly as to not thermal shock it and can't get it too hot either.

[BCM_OC]

Re: lg 60ld550

Well I was suggesting a test where you heat different parts of the boards for a minute to see if anything changes. Looks like yours was the bga problem tho, I think the heatgun method is better than the oven baking, there's a lot of things that get cooked that don't need to with the oven method. If you follow some of the pros advice on the right videos it may last quite a while. There's a good one on youtube, can't recall which one exactly but he explains it well, need to get it slowly up to temp and bring it back down slowly as to not thermal shock it and can't get it too hot either.

I agree with you. Honestly, I'm very surprised that if the solder is hot enough to "reflow" anything, that components don't fall off the back side of the board during this whole board "baking" process. I understand that there is some surface tension at play, but that's not holding anything more than SMD's. Given that, (like you) I'm of the mindset that local heating is actually "healthier" for the board than having the entire board get baked - despite the "shock" from temperature differential as some claim. Maybe I'm wrong about that, though, and someone here will set me straight.

My new (ever changing) "plan" is to do this with the Amtech flux and again use the heat gun and IR temp gun to monitor the temps, but to mask the two chips off with aluminum foil and polyimide tape to help to shield the surrounding components. Maybe it would be wise to also use the tape along the underside to help hold any loosening SMD components in place until the temps come back down.

What are your thoughts on that?

[nomoresonys]

Re: lg 60ld550

Sounds solid, yes I mean the slow rise and slow decline of temp with heatgun, I baked a board in oven in the past, was a complete failure.

[BCM_OC]

Re: lg 60ld550

Sounds solid, yes I mean the slow rise and slow decline of temp with heatgun, I baked a board in oven in the past, was a complete failure.

Failure how? What happened?

Here's what I'm (now) thinking - Tape the components on the underside of the board (under the BGA chip) with polyimide tape. Support the board under the area to be re-flowed with a polyurethane foam block, and place an aluminum foil "heat shield" in between the foam block and the taped underside of the board. This way, even (and isolated) pressure will be maintained on the underside of the board in the area that is to be heated - in order to keep the components on the underside from dislocating as the solder softens. Well, that's the plan, anyway.

[nomoresonys]

Re: lg 60ld550

It didn't work and half the plastics started to melt, I opened up all the windows and the stink still lingered for hours, that's a bad smell. Just tried googling tv mainboard reflows but most of the results are for baking, damn google.

[nomoresonys]

Re: lg 60ld550

I know they say to use the no clean flux on laptop chips, would be nice if you could get it under the tv mainboard chip if you can. Your plan looks good to me, I think good results rely on using the proper temps and time. The guy doing the laptop in the video he used heatgun, used no clean liquid flux til it ran under the whole chip, he started farther away then gradually brought it closer then heated to melt the solder for x amount of time then slowly backed off as to bring temp. back down slowly to avoid thermal shock I guess. He claimed to have great success.

[BCM_OC]

Re: lg 60ld550

I know they say to use the no clean flux on laptop chips, would be nice if you could get it under the tv mainboard chip if you can. Your plan looks good to me, I think good results rely on using the proper temps and time. The guy doing the laptop in the video he used heatgun, used no clean liquid flux til it ran under the whole chip, he started farther away then gradually brought it closer then heated to melt the solder for x amount of time then slowly backed off as to bring temp. back down slowly to avoid thermal shock I guess. He claimed to have great success.

Well, I would be very interested in seeing that. Let me know if you find it.

Planning to do this re-flow experiment this Saturday. Hoping that the flux doesn't cause the existing solder to flow or "pool" to one area under the chip, but I guess if that were the case then it would occur during manufacture and re-balling type repairs. I can't really see why it wouldn't work with some flux added in for good flow and wetting. A hot air station is how they heat up the chip for re-balling anyway, so this is essentially the same thing.

Yeah, there's definitely some odor to it. Just heating the chips on this there was a fair amount. I can only imagine what it's like with the whole board in an oven. That can't be good for you. Can't be good for the next food cooked in the oven either.

"Today we'll be having roast greenboard chicken, and for dessert greenboard cap apple crunch." Mmmmm, tasty....

[nomoresonys]

Re: lg 60ld550

[nomoresonys]

Re: lg 60ld550

One here doing a laptop: https://www.youtube.com/watch?v=w37QV0EZXQI

[BCM_OC]

Re: lg 60ld550

One here doing a laptop: https://www.youtube.com/watch?v=w37QV0EZXQI

I watched that video and I read, and read, and read, and I watched some more videos. A lot more. I now know more about BGA chips and BGA "Flip Chips" than I ever thought I would - or would want to.

While I doubt that these chips were initially designed as "planned obsolescence" for the components that they are used in, they have certainly become that. This design, combined with lead free solder, really has no alternative but to fail. Just poor design all the way around. Just terrible. Cheap and fast to manufacture though, with no socket to install on the board or pins to affix to the chip. They're pure garbage, but they usually don't fail during the warranty period, so the manufacturers really have no reason to care or to change it.

So, after my quick education on BGA chips, I decided to just leave well enough alone now that it's working again. Well, at least until it fails again - which it most certainly will.

I tested all of the outputs, and since the earlier heating and quasi "reflow" of the chip everything works again - although who knows for how long. I looked into implementing some small case fans into the back cover to help cool the board and chipsets, but found that it really wouldn't be all that beneficial. I ran some very intensive 4K demonstration videos while monitoring the two BGA (graphics?) chips on the board. After more than an hour of running these videos non stop, the larger of the two (with the large heatsink) runs at a pretty consistent 134 - 138 degrees Fahrenheit, while the smaller one runs about 10 degrees or so behind, at 122 - 126 degrees Fahrenheit. That's much lower than I expected. That is with the back cover removed from the set, though.


I think that the real issues with these chips is not heat primarily, but design and materials. I fully expect that this problem will re-occur, but I'm torn on whether "re-flowing" it now (this time while using flux) while everything is working will serve any real purpose or advantage. I would, however, do it that way if I were to have to do it again - which I'm pretty sure that I will.

Even the very best "re-balling" procedure using some of the most expensive computer automated machines and procedures is a questionable "fix" though. Leaded solder certainly helps, but the expansion/contraction effect on the ball joints is still a problem, as well as "pop corning" of the board and chip substrates, and the heat affect to the chip - to name just a few. I think that you may be able to achieve (almost) the same results from doing it manually if you're very careful and following "best practice" procedures based on some of the videos I've watched.

There are a ton of videos and articles on this. Here are a few below that I found to be very interesting.

BGA Reflow Offset
https://www.youtube.com/watch?v=ejcIyGJZD4g

Ball Grid Array Inspection
https://www.7pcb.com/blog/ball-grid-...inspection.php


https://cdn.badcaps-static.com/pdfs/...c3c7d17463.pdf



It would be very interesting to see a study comparing the longevity of the various repair methods and practices from heat gun "re-flowing" to full blown computer automated service level re-balling.