K1 U2 extraction help!
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I finally found the cause of my inability to align the band filter in my
K1 under construction. I installed the RF board U2 backwards :-[ . I've managed to suck the solder from the holes on the bottom of the board, but still have some on the top. I'm trying to salvage the IC (product detector) so am begging for advice on how to successfully free up the solder from the top of the board. This is an 8 pin DIP. Next question, is there any reason not to use sockets in this location (or any other Elecraft kit for that matter)? Thanks and 73 Gary KJ7RT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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> but still have some on the top. I'm trying to salvage the IC (product
detector) so am begging for advice on how to successfully free up the solder from the top of the board. This is an 8 pin DIP. You run the risk of damaging PCB pads if you try to extract it all at once. It might be worth ordering another IC (or begging for one from the group, since procuring a single 612 (is that the right IC?) might not be worth the effort involved via Digikey etc.) -- in fact, I'd consider asking Elecraft; as long as you're not trying to stock your lab with lots of parts, they might be willing to ship you a replacement for a reasonable fee. It's worth asking. If you go that route, just use snub-nose snippers/dykes to nip the legs near where they enter the IC package, and remove the legs one by one by heating them up and pulling them out. A lot less potential destruction to the board. If you insist on removing the IC at once, you'll need a "good" soldering iron with good staying power -- like a desktop 800 deg Weller-type, not a 20 W pencil type. I usually work on the two sides separately. Take a thick lead (from a resistor or something) and solder it to all four legs (pins 1-4) on the bottom of the PCB, and flood it with solder. This spreads the heat out and lets you release the pins on all four pins at once. If you don't do this you risk putting stress on other pins while you heat/pry one pin, and that's when you can really damage the vias and PCB. WIth all four pins heated, take a flat blade screwdriver and GENTLY pry one end of the IC, rotating the screwdriver tip to concentrate on prying the pins 1-4 side. Don't nudge too far -- just a little, then let things cool. Keep the driver in there with gently pressure applied until the solder cools, so the IC doesn't revert back to its original position. Now move to the other four pins (5-8) and do the same procedure. Then back to the first side. And so on... back and forth until it's free. Takes a while but it works. You typically need three or four hands. Again, a decent iron is a must. Unless you're comfortable with the process and have a decent iron, I'd really just snip and salvage the IC and see if Elecraft or a list member can get replacement part to you. I'd offer you one of mine but I just sold the last of my stock. --Andrew, NV1B .. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Gary W. Marklund
Thanks to all that replied on and off list. I've tried a wick and the RS
solder sucker and have the bottom clean and clear but there is still just a bit but enough solder on the top of the board to hold the IC in place. Think I'll go the safe route and order a replacement from Elecraft and clip the leads on the existing one. 73, Gary KJ7RT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Gary,
Good decision. Just think of it this way - even if it costs $25 to $30 to order one (or 2 or 3) from an electronics distributor like DigiKey or Mouser or others, that is a small price compared to the price of a board and the rest of the components that are mounted on it. In this particular case, you ae likely to get a single one for much less from Elecraft. Don't be 'penny-wise and pound (dollar) foolish' - all things have their relative value. This is not a time to fool with typical ham frugality, there is too much relative value at stake. 73, Don W3FPR Gary W. Marklund wrote: > Thanks to all that replied on and off list. I've tried a wick and the RS > solder sucker and have the bottom clean and clear but there is still > just a bit but enough solder on the top of the board to hold the IC in > place. Think I'll go the safe route and order a replacement from > Elecraft and clip the leads on the existing one. > > 73, > Gary > KJ7RT > > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Gary W. Marklund
On Fri, 2009-08-28 at 14:51 -0700, Gary W. Marklund wrote:
> I finally found the cause of my inability to align the band filter in my > K1 under construction. I installed the RF board U2 backwards :-[ . I've > managed to suck the solder from the holes on the bottom of the board, > but still have some on the top. I'm trying to salvage the IC (product > detector) so am begging for advice on how to successfully free up the > solder from the top of the board. This is an 8 pin DIP. I've had good luck with the following procedure. 1. First, remove as much of the solder as possible with a solder sucker and wicking braid. 2. Then grasp each pin from the bottom of the board with a pair of needle-nosed pliers and wiggle it back and forth to break the bond of the remaining solder. If you managed to remove almost all the solder from each hole in step 1, then you should be able to free each pin without damaging anything. If you can't clear almost all the solder from the holes (i.e. if you can't see light through all the holes), then it's best to give up on saving the IC. As others have suggested, just clip all the leads at the IC body and remove the pins individually. > Next question, is there any reason not to use sockets in this location > (or any other Elecraft kit for that matter)? In general, there are two reasons not to use sockets: 1. Increased cost. 2. Decreased reliability. That said, it can be a good idea to use sockets on a homebrew project, especially if it is a new design that you are likely to have to modify later. And, of course, a socket is needed for a ROM or other programmable device that might have to be changed later. Al N1AL > Thanks and 73 > > Gary > KJ7RT > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Gary W. Marklund
You probably made the best choice for you. If the chip is cheap - which it is just cut the pins and remove individually.
It is fairly easy to remove such a chip using hot air or thick tinned copper wire. You need to be careful with hot air but if you mask off the rest of the board with a piece of aluminium with a hole in it to view just the pins and heat from the bottom you can heat all pins at one and the chip will drop off. I have used this technique many times but usually I am interested in salvaging the component and not the PCB. If you get it too hot you can burn the PCB. I have an SMD hot air cun that makes this operation very easy. I assume you don't have one - so perhaps best to not try. The other way is with copper wire. Solder a thick piece of copper wire to all the pins at the base. Small piece of copper shim wold do as well. Then heat this with a hot iron so all the solder for all the pins melts. The chip will drop out. I wish elecrat would start to go on the SMD route. Removing SMD components is much easier. When you learn how the larger sized SMDs so are much easier to work with than leaded parts. Mike
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