On (25 May 97) Scott Christensen wrote to Ralph Mowery...
 SC> Ralph Mowery writes in a message to Harvey Harbicht
 SC> HH>People: Is it very hard to desolder/resolder surface mount diodes?
 SC> HH>I'd like to open up all freqs my Icom Z1A but ONLY if I can put it
 SC> back HH>in case it doesn't work.
 RM>  That is one of those questions where if you have to ask, then
 RM> it is probably not for you. Unless you have the special equipment
 RM> to do it, you will usually destroy the surface mounted devices
 RM> while desoldering them.
 SC> I know that you seem to know what you are talking about, but I will
 SC> attempt to enlighten the others reading these messages.
 SC> Speaking from experience - it's not too difficult to remove/ replace
 SC> diodes, resistors, transistors or capacitors using 2 soldering irons
 SC> with tiny tips used sort of like "knitting needles" - one point on
 SC> each solder junction.  It's the large devices with many leads that
 SC> take the hot-air extraction equipment.
 SC> For those who don't know, a jet of air - hot enough to melt solder is
 SC> directed onto the area of the board where the device is.  There is
 SC> often a vacuum pump and a "pick up" that will lift the device from the
 SC> board as soon as the solder melts.  To replace the device you can
 SC> either reverse the process, or if the leads are external to (not
 SC> under) the device you can use standard soldering methods.  It helps to
 SC> have the board really clean of old solder and use some liquid flux on
 SC> the pins of the device before you start soldering.
 SC> The whole process is *not* for the short of money or faint of heart!
 SC> It also explains why it is often cheaper to replace a board in modern
 SC> scanners rather than trying to repair it.
I did the "business" band mod to my Pro-39, using a solder sucker,
solder wick, and one soldering iron. I didn't think of using two
soldering irons, that would have probably made things easier. Using
one iron, I managed to get 99% of the solder off the device and then
had to do a minor "reheat" of the device, while applying light
pressure to the device to get it loose. I am very glad I didn't have
to reinstall that SMT Diode anywhere else. It was so small, I would
have been very worried about making a solder bridge.
I agree, it is definitely not for the faint of heart.
Martin
... Me...a skeptic?  I trust you have proof.
--- PPoint 2.03
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