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Premium Member 2004 SLK32 AMG
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5,179 Posts
Discussion Starter #1
Not really a DYI person. Read the previous posts on re-soldering a K-40. Perhaps I have misssed something.

The Problem...attempted to re-solder by melting the existing solder, and/or to remove and put new solder. Solder gun would not even begin to melt the old solder.....so, took a nail and heated it with a torch. Got it red hot and place against solder. Not even a hint of melting!! 馃槪

And the solution is ????? 馃槼
 

Premium Member 2002 SLK320
Joined
627 Posts
It's not really necessary to remove and replace the solder. All you need to do it hold the soldering iron on the solder until it melts, then remove the soldering iron and let the solder cool. If your soldering iron isn't melting the solder then you don;t have one with a high enough wattage. I managed to do mine with a fairly small one (30W, I think). Try a small solder blob and see if it works on that. It can take a few seconds for the solder to melt, maybe you aren't holding it on long enough.
 

Premium Member 2004 SLK32 AMG
Joined
5,179 Posts
Discussion Starter #3
It's not really necessary to remove and replace the solder. All you need to do it hold the soldering iron on the solder until it melts, then remove the soldering iron and let the solder cool. If your soldering iron isn't melting the solder then you don;t have one with a high enough wattage. I managed to do mine with a fairly small one (30W, I think). Try a small solder blob and see if it works on that. It can take a few seconds for the solder to melt, maybe you aren't holding it on long enough.
I will check the wattage on the soldering iron. Can't get it to melt......I thought for sure the head of a torch-heated nail (smoking red hot) would melt it...but it didn't. The nail put enough heat in the solder to start sweating the board under the solder, but didn't melt the solder.
 

Premium Member 2014 SLK55 AMG
Joined
1,652 Posts
The SLK's were coming on the market just as ROHS regulations were getting off the ground. The new solders need quite a bit more energy to get to liquid state. They also don't flow as well.

Your K40 board has an environmental protective coating on that is surprisingly heat resistant. You do need a good sized Iron 90 Watts or so and a broad chisel tip to get it going. Scraping the coatings off with a scalpel will help.
 

Premium Member 2002 SLK320
Joined
627 Posts
The SLK's were coming on the market just as ROHS regulations were getting off the ground. The new solders need quite a bit more energy to get to liquid state. They also don't flow as well.

Your K40 board has an environmental protective coating on that is surprisingly heat resistant. You do need a good sized Iron 90 Watts or so and a broad chisel tip to get it going. Scraping the coatings off with a scalpel will help.

Ah! That would explain why I struggled with my 30W. It did seem hard work at the time.
 

Super Moderator UK 2002 SLK320 Blue
Joined
2,846 Posts
I've always said a good, 50W plus iron is needed to mend a K40. Any hobby iron (usually 15-25W) hasn't got the heat capacity to melt the solder and reflow it. Indeed, an iron that is too small would likely leave you with dry joints, which will worsen the situation. (Dry joints are not dull or shiny but crystalline in appearance and do not conduct electricity as well)

Also, you should also add fresh solder to the joint as you melt it to help the solder flow and to provide flux which is needed to keep the joint clean.
 
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