There are not a lot of "bad ideas" in terms of desoldering because there are many ways to attack the problem. But some means of attacking the problem (capacitor replacement) are better suited to some than others. Some methods require more patience and skill than others. Although I have an EE degree and have years of soldering experience, I still prefer pro tools to make my job easier and ensure the job is professional and quite nearly "perfect."
Just don't scratch your board, which could brake a trace. That could happen if you apply too much pressure to a normal soldering iron (or two, one in each hand), and your hand slips and a sharp iron tip sinks into your board and digs a 4cm trench in it! I've seen this happen!
Don't apply too much heat. With a professional tool you can adjust the heat, but with a $9 iron, you cannot. But if you buy a low wattage iron (around 25W) it may not provide enough heat so you may hold it on the board too long and over heat some parts. There is a lot that can be said about this point, but it's too much for me to write here. Suffice it to say, you need to apply "the right amount" of heat to melt the solder and remove the component.
Solder braids or wicks will help this sometimes, but you can't always pull all the solder away from SMD components this way (I know this firsthand), and sometimes you will get frustrated and yank on the SMD part and brake a pad and/or trace. With my HAKKO tweezer this never happens because I am not interested in cleaning up the solder and then pulling on the part. With the tweezer, I heat the solder to melt it on both sides of the part and then easily pull off the part. It works well, without any desoldering braids or pumps.
Anyway, you need to desolder all your caps (making sure you first have the new caps handly), then clean the board with something like 99.5% pure dehyrated Ethanol alcohol (I advise against "rubbing" alcohol), then solder in your new caps. (Sorry for the Japanese link, but I live in Japan and source my Ethanol here too.)
Now I have long contended, and still do, that you should replace all the caps, including the two axial caps, in one fell swoop. While others may say you can see or smell leaked fluid, I for one cannot. I tried easy method once (replacing only the caps around which I physically could see leaked fluid). That didn't solve my problem. I then replaced all the caps and the problem went away. And since most of these electrolytics contain fluid, and since many have leaked, and since all will leak at some point, why NOT do all of them at once! Because if you only do a few, what if you get a system crash now and then you cannot explain? There will always be the possibility that you didn't replace one or more caps that you should have. So I strongly recommended doing the ENTIRE BOARD, SMD caps and the two axials too.
Lastly, while I am by no means an "expert" on SE/30 repairs, if you wish to read much more on this subject, you can just search this site for "caps" or "capacitors" or "Ethanol" along with "JDW". You can Google for that too, as I am known as JDW on most other classic Mac sites, and I have written many of the same words over and over and over again on many sites. Some threads contain more detail the use of Ethanol as opposed to other cleaning methods, other threads talk more about types of capacitors to use a replacements, etc. Just do a little searching with "JDW" as a keyword and you're bound to find a wealth of information. And no, this is not a plug for me. I simply like to participate in these discussions to see what others have done and to share my own experience to help others avoid the same pitfalls that affected me when I first started out.
Just don't scratch your board, which could brake a trace. That could happen if you apply too much pressure to a normal soldering iron (or two, one in each hand), and your hand slips and a sharp iron tip sinks into your board and digs a 4cm trench in it! I've seen this happen!
Don't apply too much heat. With a professional tool you can adjust the heat, but with a $9 iron, you cannot. But if you buy a low wattage iron (around 25W) it may not provide enough heat so you may hold it on the board too long and over heat some parts. There is a lot that can be said about this point, but it's too much for me to write here. Suffice it to say, you need to apply "the right amount" of heat to melt the solder and remove the component.
Solder braids or wicks will help this sometimes, but you can't always pull all the solder away from SMD components this way (I know this firsthand), and sometimes you will get frustrated and yank on the SMD part and brake a pad and/or trace. With my HAKKO tweezer this never happens because I am not interested in cleaning up the solder and then pulling on the part. With the tweezer, I heat the solder to melt it on both sides of the part and then easily pull off the part. It works well, without any desoldering braids or pumps.
Anyway, you need to desolder all your caps (making sure you first have the new caps handly), then clean the board with something like 99.5% pure dehyrated Ethanol alcohol (I advise against "rubbing" alcohol), then solder in your new caps. (Sorry for the Japanese link, but I live in Japan and source my Ethanol here too.)
Now I have long contended, and still do, that you should replace all the caps, including the two axial caps, in one fell swoop. While others may say you can see or smell leaked fluid, I for one cannot. I tried easy method once (replacing only the caps around which I physically could see leaked fluid). That didn't solve my problem. I then replaced all the caps and the problem went away. And since most of these electrolytics contain fluid, and since many have leaked, and since all will leak at some point, why NOT do all of them at once! Because if you only do a few, what if you get a system crash now and then you cannot explain? There will always be the possibility that you didn't replace one or more caps that you should have. So I strongly recommended doing the ENTIRE BOARD, SMD caps and the two axials too.
Lastly, while I am by no means an "expert" on SE/30 repairs, if you wish to read much more on this subject, you can just search this site for "caps" or "capacitors" or "Ethanol" along with "JDW". You can Google for that too, as I am known as JDW on most other classic Mac sites, and I have written many of the same words over and over and over again on many sites. Some threads contain more detail the use of Ethanol as opposed to other cleaning methods, other threads talk more about types of capacitors to use a replacements, etc. Just do a little searching with "JDW" as a keyword and you're bound to find a wealth of information. And no, this is not a plug for me. I simply like to participate in these discussions to see what others have done and to share my own experience to help others avoid the same pitfalls that affected me when I first started out.