Ralph Mowery writes in a message to Harvey Harbicht
  
HH>People: Is it very hard to desolder/resolder surface mount diodes?
HH>I'd like to open up all freqs my Icom Z1A but ONLY if I can put it 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. 
  
I know that you seem to know what you are talking about, but I will attempt 
to enlighten the others reading these messages.
  
Speaking from experience - it's not too difficult to remove/ replace diodes, 
resistors, transistors or capacitors using 2 soldering irons with tiny tips 
used sort of like "knitting needles" - one point on each solder junction.  
It's the large devices with many leads that take the hot-air extraction 
equipment.
  
For those who don't know, a jet of air - hot enough to melt solder is 
directed onto the area of the board where the device is.  There is often a 
vacuum pump and a "pick up" that will lift the device from the board as soon 
as the solder melts.  To replace the device you can either reverse the 
process, or if the leads are external to (not under) the device you can use 
standard soldering methods.  It helps to have the board really clean of old 
solder and use some liquid flux on the pins of the device before you start 
soldering.
  
The whole process is *not* for the short of money or faint of heart!
  
It also explains why it is often cheaper to replace a board in modern 
scanners rather than trying to repair it.
 
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