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Discussion Starter #1
Going to attempt to replace buffer chip on sdr board, buying a weller wes51 station, is this a good one for this type of repair?
 

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It can be adequate, depending on the method used. Short of buying a hot air station I would not spend more than this. I would recommend a wedge tip to hold more heat for removal, and you will need lots of eutectic solder or some chip quick.
 

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Discussion Starter #3
Thanks, I planned on the hoof style tip....where is a good place to get the solder...I am going to practice on an old laptop..thanks again..
 

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Most of the better suppliers have hd it in the past. I have not bought any in over a year, however, and understand prices have risen. I suggest checking several sources such as Acme, Encompass, Andrews, MCM, DigiKEy, etc.
 

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I recommend practice on an old board. The first time changing a flat pack IC can be a challenge.
 

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Well that didnt last long, I bought some chip quik and tried to unmount the old buffer chip and it appears to be soldered in the middle of the chip too, I would take it that you need hot air to unmount the old chip? I am just going to solder in the new caps on the power board and buy a new sdr-u board. This site is really awesome and provides alot of references!
 

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Not soldered, but glued. If you use the technique that I have described here the chip gets hot enough to melt the glue. I never use chip quick. I use a lot of eutectic solder to form a large bead around the entire chip. This holds enough heat to keep all sides melted and the chip lifts rigth off. Hot air is nice if you can afford the investment, but even in the repair business, I never could.
 

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Your post has been moved to a more appropriate location to make information easier to find and to make it more likely that others who are interested will find your post.
 

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Discussion Starter #10
Thanks for the info, would this method of running a bead of solder around the chip ruin the chip? I planned on saving the other board to remove and replace the chips on other boards if one goes bad. But maybe it would be best to just get new ones since they are cheap..
 

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Discussion Starter #11
Oh and by the way this Digikey company is awesome! They have everything you could want and they got my shipment out really fast! Thanks...
 

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Discussion Starter #12
Well looks like I learned something the hard way, I installed the new caps in the powerboard, put the old sdr u borad in and turned it on to see what would happen, it came on but with some lines screwed up, so i unplugged the top sdr from the y sustain, and turned it back on and blew a chip in the lower buffer baord! Oh well gotta get 2 now..
 

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Thanks for the info, would this method of running a bead of solder around the chip ruin the chip? I planned on saving the other board to remove and replace the chips on other boards if one goes bad. But maybe it would be best to just get new ones since they are cheap..
I am not far from you right now. I am up by belle vernon/ charleroi pa area right now at my parents house for the holidays.
 

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This is good info. I'm also trying to repair an SDR-U board out of my P50S601. This board has 1 bad chip. My TV is up and running thanks to this forum. I installed a new SDR-U board but would like to have a spare just in case. I never worked with flatpacks before so I knew this might be a challenge.

After removing as much of the silicone as I could, I tried to run a bead of solder around the chip but the solder would just ball up on the end of the soldering iron. I'm guessing this was due to silicone residue on the pins. I'm not sure what to use to clean the pins better. So I went to plan B and cut all the pins from the case with an exacto knife and desoldered them from the board. This is where I also found out the the chip was bonded to the board. I then decided to hold off until I got more info.

So my question is, does the adhesive under the chip server any other purpose other than to hold the chip in place for assembly? Is it necessary to use special adhesive for heat dissipation?

I used to work with modules that were installed in an F15 radar system. These modules contained ECL gate arrays that ran very hot. These gate arrays had to be bonded to the board with a special silver epoxy for heat dissipation. Otherwise, they would burn up.

Thanks,
George
 

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Discussion Starter #18
Hi George, well I did use some desoldering wick and flux and removed the solder form the pins, I know I had it all off and tried to pry the chip from the board and the old chip broke, so i chipped off the rest of it and all that was left was the small square middle piece bonded to the board, it was sort of a small copper square, so I had to put ALOT of heat on it to remove it. What appeared to be underneath bonding it to the board was a solder looking material, it was very silver in color so guess it could be the stuff you mentioned. I think hot air would work good with this but I am not a pro, but it sems to be what is needed to properly remove this. Of course you could just break the chip and remove the middle piece but then I dont know what is needed to install the new chip.....paste solder maybe?? This is getting way too touchy for me!! haha...well good luck on yours and let me know how it goes...
 

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Very interesting. It sounds like yours was soldered to the board. I noticed the small square on the bottom of my new chips but couldn't really see it that well because they are sealed in anti-static bags. I was thinking about using my dremel tool to grind the chip down if I couldn't get enough heat on it. LOL Getting the chip off the board is the 1st order of business.

A friend of mine mentioned solder paste but that would require heating up the chip during installation. Then you run the risk of frying the new chip if you apply too much heat. I need to research this a little further. I've done a lot of soldering but nothing like this. Another option would be to bond a heat sink to the top of the chip. Another thing, I'm not going to seal the pins with silicone. It's not really necessary.

Anyway, I'm going to attack mine this weekend. I'll let you know how it turns out. This is just a spare board for me so I'm not that concerned but it would be nice to get it right. I won't even be able to test this board unless my TV dies again. It took quite awhile to align the SDR connectors. I don't want to do it again unless I have to.
 

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I finally got the the bad chip off of my SDR-U board. What a chore. As it turns out, there was plate on the bottom of this chip that was soldered to the board for heat dissipation. So I put the largest wedge tip that I had onto my soldering iron and tried to heat up the chip. No matter what I did, I couldn't get enough heat through the chip to break the solder bond underneath. I even tried heating up the back side of the board with no luck.

So finally, I put some flux onto the chip and heated up the chip by feeding lots of solder to tip of my iron so the heat would spread out. This only allowed me to break up the chip by putting some pressure onto the side of the chip with an exacto knife. Finally, a small piece to the plate underneath the chip was exposed. As soon as I touched it with the soldering iron, it popped off.

I lost a couple of pads in the process. Fortunately, the lost pads were tied to the pin next to it so the board is still useable. I was able to find a new SDR-U board on Ebay for $75 (as least that is how it was advertised). The seller (in New Jersey) is still on Ebay with more boards that he sells paired up with the SRD-D board for $139. Search for J6079 or J6080. The new board is working great in my TV.

Repairing this board didn't come out as good as I hoped but if I paid someone else to do it, it would have cost me at least $75 anyway.
 
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