MOTM

Well, I need some advice.  First, let me give some. Never let your 
dear wife distract you while building something complicated.

That being said.  In my current build project, MOTM 440 Filter, I have 
managed to get all of the 2220 and 2210 IC's backwards.

I have managed to get one of them unsoldered after about an hours 
worth of work. I have a good solder sucker, but it seems minute 
amounts of solder are still hanging around causing the chip to adhere 
to the board.

Anyone have and good suggestions on how to get the little buggers off?

Thanks

Bruce

In a message dated 4/22/2001 4:11:00 PM, bruce@... writes:

>I have managed to get one of them unsoldered after about an hours 
>worth of work. I have a good solder sucker, but it seems minute 
>amounts of solder are still hanging around causing the chip to adhere 
>to the board.
>
>Anyone have and good suggestions on how to get the little buggers off?

If you have one of those sucker bulbs that one is to use in conjunction with 
a soldering iron, you are wasting your time -- it will never work (why do you 
think they call them "suckers")!

I got one of those "deluxe" Radio Shack Desoldering Irons (a bulb and iron in 
the same unit), I think it cost me about $8.00. I have had a good bit of 
success with this tool, and real desoldering stations cost real money.

The bad news is that the through plated holes are really good at allowing the 
solder to pass from one side of the board to the other -- making it a bear to 
desolder. Take your time with those SSM ICs since they will be hard to get if 
you screw one up. I'd suggest doing one or two pins per IC, then walk away 
for a few minutes.

Good luck!
JB

bruce@... writes:

>>I have managed to get one of them unsoldered after about an hours  worth of 
work. I have a good solder sucker, but it seems minute amounts of solder are 
still hanging around causing the chip to adhere to the board.
Anyone have and good suggestions on how to get the little buggers off?<<

I don't know if solder wick will help here.  I sometimes have to use both 
solder wick and a solder sucker depending on the circumstances.  However, I 
had to remove two regulators recently and even just getting one of those 
simple devices out was a 10 minute ordeal with me worrying that I'd start 
pulling the traces off the PCB in the process.  I just said to hell with it, 
clipped out the second one and bought new replacements in my last Mouser 
order.  Sometimes it's easier to do that if you are dealing with inexpensive 
parts.

-Elhardt

Just a bit of an update.  It took time and determination, but I got 
them all out, destroying only one of the upper pads in the process.  
Word to the wise, it takes a long time to take these out. It would 
have been far easier to do it right the first time... check and check 
again.

Anyhow, upper pad was repaird, they are all back in.  I caught this 
just moments after finishing the IC soldering stage, so I will wire it 
up tomorrow and hopefully have a lovely SSM 2040 clone tomorrow.

Thanks for all the suggestions.

Bruce

Hi all,

The SSMs are eight pin DILs. Go get a bit for your iron that heats all
eight pins up at the same time. Most of the big mail order guys do one.
You then pull the chip out with a chip extractor or a little
screwdriver. It may be cheaper than buying a load of SSM2220/2210.

The way I do it, and I have never had to cut a 8 pin DIL off at the
body, is to heat one row of the legs at once with a normal 5mm bit. Use
lots of fresh solder smother the pads in solder, you can always soak it
up later. Prise the IC up with a screwdriver. Then do the other side.
Spend only 10 seconds or so to do each side to keep the temp of the IC
down.

For a 14 pin DIL, I would probably go for the cut legs method.

OR... only for the very brave/stupid, ie. not me :-) Gas blow lamp on
'fine' 20mm wide flame. 2 second burst on the back of the board aiming
at the IC. Then immediately bang the board onto the bench and the IC
drops out. I never tried it, but I had a colleague who dumpster dived
computer boards to rescue ICs who did this regularly.

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan

At 12:08 AM +0000 04/23/01, bruce@... wrote:
>
>I have managed to get one of them unsoldered after about an hours
>worth of work. I have a good solder sucker, but it seems minute
>amounts of solder are still hanging around causing the chip to adhere
>to the board.
>
>Anyone have and good suggestions on how to get the little buggers off?

I use Chem-Wick.  It's about $3 a roll and lasts a very long time.  I try
not to solder IC's in backwards, so I've used the same free sample I got
back in the mid-80's when Chemtronics first introduced it :)

I have a Paladin solder sucker, but it isn't very useful for PCB's -- it's
good for big stuff.

You can also try using a piece of braided shield from a coaxial cable.  Cut
a little piece about 1/4" square and hold it next to the joint with your
iron.  The solder should wick onto the braid.  Of course you have to do
this for each pin.

They also sell spring loaded IC extractors -- I've never used one.  I use
this thing that looks like a pair of ice tongs that came with a ROM upgrade.

Then again, Paul doesn't think my soldering is very good -- so maybe you
shouldn't listen to me :)