Uh... someone walk me through the best way to remove an SMD opamp.

[nbabmf]

I think I've narrowed the problem down with this dead DD-3 to the 4558 that buffers the signal.  I plan to remove it, put a socket in it's place, and pop a 4558 I have lying around in there.  The purpose of the socket is so I don't have to bend the pins and directly solder the IC to the board.  I have a million sockets, but only one IC.  I'll also be able to pop it out later when I want to mess around with Tube Screamers

[JKowalski]

This sounds like a difficult venture.

Since it's only 8 pins, you can probably do this: get a piece of solder wick, lay it across the leads on one side, and heat all the pins at the same time by running the iron along the wick. Then pry it up, move to the other side, and repeat.

There is also this special type of solder that stays molten for like 10 seconds - used for exactly this purpose. You mix it in with the solder holding the SMD chip down, doing each pin in turn, and if you are quick then by the time you are on the last one all the solder is still molten and you just take it off.

Go on youtube and look up "desoldering SMD", and you'll find alot of good videos on it.

[Blue_Toad]

Common practice if you know that the part is dead is to use an Xacto knife to cut the legs near the black plastic. Then once the body is gone, use the soldering iron / wick to remove the legs and the left over solder. Much easier this way and much less likely to lift/ damage a pad.

BlueToad

[nbabmf]

Thank you!  I cut the body from the legs with an Exacto knife.  Now I just need to find tweezers small enough to let me pull the legs out when the solder is melted.

[Blue_Toad]

Glad to hear it worked, most of the time I've found that you don't need tweezers, you'll want to clean up the pads with solder wick if you're planning on putting something else down and I've found that most of the time those little legs stick to the wick as well as the solder. That's just my experience, results may vary.

BlueToad

[nbabmf]

Now for the real fun part... getting that socket onto the board.  I had to bend the legs a little inward, sacrificing space to fit the iron.  And it was already a tight squeeze!

[Processaurus]

Heat gunning is one of more painless ways to get surfacemount chips off and on, as long as the heat doesn't melt wires. 

kludging a DIP socket on SOIC pads sounds painful, because they use 50 mil spacing for the surfacemount chips and 100 mils for the DIP.  Maybe possible to scavenge one out of some broken equipment from the 90s or later.

[Cliff Schecht]

Another really neat trick for SMD parts is to take two irons and heat both sides of the IC at the same time. Once you do it a few times, you get the hang of grabbing the IC with the soldering irons and it works like butta.

[nbabmf]

Ah, clever!  I would think the heat would be too much and melt/burn the IC.

Well, I got the old chip out, painstakingly bent the pins and installed a socket, and put a new chip in.  It now passes a bypass signal, but very quietly and still no delay effect.  I know it should be louder because the direct out is pretty loud in comparison.  I tried registering at Boss Area because there are a lot of people familiar with the DD-3, but my activation isn't going through and no one seems to be at the helm this weekend.

[Top Top]

I actually built an LFO using one of those tiny SMD chips once - a 40106... I ordered it accidentally instead of the normal size. I soldered to it using my crappy 15 year old $10 radioshack soldering iron. That was fun 

Luckily it was only four or five of the 14 pins that I needed to connect.

[Sir H C]

Are you sure the SMD op-amp pinout = the DIP one?  Often they are different as the paddle might need specific pins as ground. 

[nbabmf]

I believe so.  I assumed it was the same because I'm using a 4558 DIL and it worked for someone else with the same pedal.

[JKowalski]

Ah, clever!  I would think the heat would be too much and melt/burn the IC.

Would it matter?