De Solder SM electrolytic caps
in [Repair]
|
From: RubbishRat on 1 Apr 2010 18:10 Hi, Does anyone have any good tips for desoldreing these SM caps without damaging the pads? I tried wicking each pad dry but the darned thing still took one of the flimsy little pads off with it. Also would it be OK to replace a SM cap with a similar value radial if I support the radial with a blob of silicon sealer or something after soldering ? Any help welcomed. -- Just add a little Rub to email me :^)
From: Jeffrey D Angus on 1 Apr 2010 18:32 RubbishRat wrote: > Hi, > Does anyone have any good tips for desoldreing these SM caps without > damaging the pads? > I tried wicking each pad dry but the darned thing still took one of the > flimsy little pads off with it. Also would it be OK to replace a SM cap > with a similar value radial if I support the radial with a blob of silicon > sealer or something after soldering ? > Any help welcomed. > > Two small soldering irons. The poor man's SM tweezers. Jeff -- �Egotism is the anesthetic that dulls the pain of stupidity.� Frank Leahy, Head coach, Notre Dame 1941-1954 http://www.stay-connect.com
From: Martin Crossley on 1 Apr 2010 19:37 Meat Plow wrote: > On Thu, 01 Apr 2010 17:32:53 -0500, Jeffrey D Angus > <jangus(a)suddenlink.net>wrote: > >> RubbishRat wrote: >>> Hi, >>> Does anyone have any good tips for desoldreing these SM caps without >>> damaging the pads? >>> I tried wicking each pad dry but the darned thing still took one of >>> the flimsy little pads off with it. Also would it be OK to replace >>> a SM cap with a similar value radial if I support the radial with a >>> blob of silicon sealer or something after soldering ? >>> Any help welcomed. >>> >>> >> >> Two small soldering irons. The poor man's SM tweezers. >> >> Jeff > > Or an SMT tweezer iron tip. Just a couple bucks from digikey Sometimes the glue securing the pads to the PCB is strong enough to allow a solder blob on each lead huge enough for the second to remain molten while the first is re-heated and the capacitor quickly, but gently, lifted off. If there's a hiss or a fishy smell, the leaked electrolyte definitely needs cleaning off with an ionic solvent and any nearby tracks inspecting.
From: Arfa Daily on 1 Apr 2010 21:28 "RubbishRat" <bishrat(a)hotmail.com> wrote in message news:Xns9D4DEBCBB186Cbishrathotmailcom(a)216.196.109.145... > Hi, > Does anyone have any good tips for desoldreing these SM caps without > damaging the pads? > I tried wicking each pad dry but the darned thing still took one of the > flimsy little pads off with it. Also would it be OK to replace a SM cap > with a similar value radial if I support the radial with a blob of silicon > sealer or something after soldering ? > Any help welcomed. > > > -- You would think that it would be ok to sub a regular electrolytic for a s.m. one, but in my experience, it seldom seems to work, and I've never really figured out why, except that the ESR of s.m. caps seems to usually be considerably higher than that of the same value cap in a conventional wire ended package. Maybe the designers have to take this into account ? A classic example is the three little 47uF s.m. electros that you find on the servo board under some Sony CD mechs. These caps have a habit of leaking, and causing poor 'playability', but if you try replacing them with conventional electros, the servos barely work, if at all. Replace them with original surface mount types, and the performance is returned to 'ex-factory'. As for getting the little muthas off the board, I tend to flood the pads with new solder first (always nice low melting point leaded, even if the board is constructed in lead-free), and then heat one side and lift gently with a scalpel tip, and then repeat for the other end. In stubborn cases, like others have suggested, I use two irons, with their temperatures cranked well up ... Arfa
From: Jim Yanik on 1 Apr 2010 23:46
Jeffrey D Angus <jangus(a)suddenlink.net> wrote in news:hp36up01f6t(a)news5.newsguy.com: > RubbishRat wrote: >> Hi, >> Does anyone have any good tips for desoldreing these SM caps without >> damaging the pads? >> I tried wicking each pad dry but the darned thing still took one of >> the flimsy little pads off with it. solderwick is noted for removing SMD pads; you have to apply too much heat to get the wick hot enough to wick up solder. >> Also would it be OK to replace a >> SM cap with a similar value radial if I support the radial with a >> blob of silicon sealer or something after soldering ? >> Any help welcomed. >> >> > > Two small soldering irons. The poor man's SM tweezers. > > Jeff > > get a soldering iron that will accept a 6/32 screw where the tip belongs,then cut and form some thickwall copper tubing into an L shape,with a notch on one side that fits the SMD you're trying to unsolder. then drill a hole for the 6/32 screw on the other side of the L. you've just made a custom SMD desoldering tip for caps or resistors. you'll need several different sizes. -- Jim Yanik jyanik at localnet dot com |