#agc #smd (Too) Close Encounter With SMD Technology #smd #agc


Jon Reck W8REA
 

I'd finished my 40m QCX mini and had started wiring the AGC module. Thoughtlessly, I bent the wires on the bottom of the main board at a 30 degree angle, like I would when soldering a component. Bad idea! The bend brought the solder blob too close to the nearby SMD component, which I discovered after snipping the excess lead. I tried to open up the space a little by nudging the wire stub with my side cutters but bumped C17, breaking the connection on one end and twisting it.. C17 is a 39nf SMD capacitor and measures just about 1mm long- astonishingly small and fragile. I tried to re-solder it in place but when I straightened it the other end detached. Long story shortened, I ended up soldering wires to the C17 pads and then attaching a normal size 33NF capacitor to the wires, bending it over and nestling it into an unpopulated space on the board. This repair was successful and even cleared the bottom of the case.  Beware!  We are approaching the realm of micro-surgery when soldering in that densely populated area and use extreme caution- I know I will next time....

Jon W8REA


Rob Giuliano
 

I have experienced similar situations.  The issue comes with trying to break the 'short' by 'nudging'.

I find the best solution is to use a solder sucker to remove the solder from the through hole device (and therefore the surface mount 'short'). 
This may remove some solder from the surface mount device as well.  Since the other side of each device is still soldered in place, neither device is likely to move.  Also, the same amount of wire from the through hole device should be sticking down through that hole (or you may have to push it down a touch).  Then "CAREFULLY" re-solder the ends of each device.

This has worked well for me since my "similar experience".

--
Rob KB8RCO


Jon Reck W8REA
 

Thank you, Rob

That is useful information. I appreciate you sharing your experience. I've certainly learned more than I expected to building this kit :-)

Jon W8REA