How to recap a receiver?

Discussion in 'Solid State' started by Starrider1, Aug 14, 2007.

  1. Starrider1

    Starrider1 New Member

    I am interested in learning to recap one of my receivers. What type of soldering equipment should I buy and what other tools would be required. Is there any written information I could get to provide instructions other than the schematics of the reciever? Please post your advice. Thanks
  2. ticntoc

    ticntoc New Member

    This has been covered from time to time on the forum You may want to do a search for more infor. If there is not a primer on soldering, maybe there should be. At the risk of annoying some of the old goes! :D

    If you want to do a complete recap you need to get a manual (eBay). Get a good quality 40+ watt soldering iron. I like adjustable irons (set to 700 deg) with a variety of tip styles. Higher wattage irons let you get on and get off in 3-5 seconds or you may lift a pad or delaminate a board. This is also helpful as the (-) side of the caps are generally attached to a large ground plane. This can take lots of heat to remove. Same with terminals where there may be a transistor leg, caps, resistors etc. Get some "solder wick" (tm) de-soldering braid, I like it better than the spring loaded vacuum pump thingy. Get liquid solder flux, SN60 or 63 rosin core solder (prefer 63 melts at a lower temp). NO silver or acid core solder(for doing plumbing). You well wreck the boards. Good quality needle nose pliers and dikes (cutters)-small, not the ones for automotive or house wiring! Like my dad said “the most expensive tools are the cheapest”

    Clean the component leads and tin with solder. Clean the pad (see below). A touch of solder to the iron. Get both parters hot at the same time and flow some solder. Slightly concave and smooth and shinny is the order of the day.
    Remember..3-5 seconds and off.

    As far as clean up goes, use isopropyl alcohol with a small short bristled brush. I lop off about half of an acid brush. I guess a small paint brush would work. The bristles need to be short and stiff enough to get in some good scrubbing action. Scrub the joint with alcohol then sop up the mess with a chunk of paper towel, the brush and a little more alcohol. It will leave the joint smooth and shinny. I used it all over the PCB on my Scott and cleaned off all sorts of old solder flux, smoke and general gunk. BTW, this is the same process used in Aerospace to clean boards.

    Instructions? Use a scrap board first. Find someone with a Mil Std training manual for soldering. I wonder if you can find a DVD on EBAY? :thmbsp:

  3. EchoWars

    EchoWars Working a Deal in Denmark

    I wouldn't know where to begin. I would say that desoldering is an art form, especially on vintage gear where the foil traces are very easy to destroy.

    Not trying to discourage you, but unless you have some real experience soldering and desoldering, you can he headed for a real nightmare.

    -Soldering Iron (too subjective for me to make a specific recommendation)
    -Solder sucker or a combination iron and sucker bulb (RatShack sells one that many here seem to like)
    -Desoldering braid
    -Flux paste
    -Kester 44 solder (I like the 21ga [0.031"] stuff)
    -Machinist's scribe (to lift leads off the pad after the solder is sucked off or wicked off with the braid...heat the pad then use the scribe. I also use the scribe to put a tiny dab of flux on the pad before I solder the new part in place...makes for the perfect solder joint)
    -Acetone & cotton swabs (for cleaning old and new flux from boards. Alcohol is too weak to get the job done)

    You'll have to learn to read a schematic on your own. Most show a different symbol for electrolytic caps than other types. There's thousands of possible replacement types, and you'll have to get a feel for what will fit where...for the most part, new caps are a fraction of the physical size of the original. But not always.

    Get some old POS thing that you don't care about and learn to desolder without tearing the board up.
  4. Bunny

    Bunny DON'T PANIC

    I aggree. Good soldering needs excersise. Don't start mending with the solderin (it is NOT glue or something ;) ). And search for the good temperature first, it has to melt nice and fast but it shouldn't melt too fast or start vaporising...
  5. fiddlefye

    fiddlefye AK Subscriber

    I'm thinking starting a similar project and I had thought I'd hit SA or someplace and find a few really cheap pieces to try disassembling and re-assembling before taking on anything important. Good idea?
  6. REDone

    REDone New Member

    Nobody's mentioned a good magnifying glass or eye glass ??
  7. Starrider1

    Starrider1 New Member

    Thanks for all the information guys. I wouldn't think of working on one of my good receivers to start, just one of my cheap units I dont care about. My background is in computer/network and not board level electronics. I find that there are not many technicians around my area that work on vintage electronics. I am close to retirement age and ready to start the second half of my life, and since I am addicted to vintage electronics and music, I thought I would start out trying to gain some of the skills sets you probably already have and at the same time satisfy my curiosity and love for music and hardware. I don't see any young people around learning what you guys do, so it seems like trying to learn some of these skills would be fun and useful at the same time. I really appreciate the advice and sharing of your knowledge and parts through this forum.
  8. Paul C

    Paul C New Member

    Buy the thinnest solder. 50-50 or 60-40 Rosin Core. Thinner solder melts quicker and is easier to use on tight circuit boards.

    I agree, soldering braid (Solder Wick) is the thing to use on circuit boards for most work.

    30-40w Weller pencil type iron. Leave the big Weller 250 w soldering gun in the toolbox. NOT for circuit boards.
  9. Scorpion8

    Scorpion8 Active Member

    Try this place. If you browse around he has some downloadable videos on basic soldering techniques which may help, including a good discussion of what you need.

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