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cleaning pin holes to replace dip-20 — Parallax Forums

cleaning pin holes to replace dip-20

mosquito56mosquito56 Posts: 387
edited 2009-07-30 14:12 in General Discussion
·Having a terrible time replacing· a dip-20 chip. I cut the chip out but cannot clean the holes to get the new chip in.

· I tried: solder wick(solder sucker), no luck
············ solder bulb, no luck
············ using solder to tin a bare wire and remove solder, no luck

Driving me crazy, help.

·How do I clean the holes?

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······· "What do you mean, it doesn't have any tubes?"
······· "No such thing as a dumb question" unless it's on the internet


Post Edited (mosquito56) : 7/29/2009 11:19:39 PM GMT

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-29 22:55
  • David BDavid B Posts: 592
    edited 2009-07-29 23:09
    I'd suggest heating the hole then sticking a steel needle through.

    Whether the holes are blocked with just solder, or also with bits of sawed-off chip legs, I would think the needle should force the hole clean.
  • mosquito56mosquito56 Posts: 387
    edited 2009-07-29 23:19
    Solder suck and solder wick are the same thing.



    David, I tried using a needle, a resistor, and a solid wire, no luck.

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    ·······

    ······· "What do you mean, it doesn't have any tubes?"
    ······· "No such thing as a dumb question" unless it's on the internet
    ········
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-29 23:29
    mosquito56 said...
    Solder suck and solder wick are the same thing.
    The hell they are. You obviously didn't click on the link I provided.

    -Phil
  • Lab RatLab Rat Posts: 289
    edited 2009-07-29 23:59
    ok i have had this problem solder wick doesnt work very well with almost no solder in the hole (on the surface) what you do is take 60/40 (WITH LEAD) (or whatever solder you have that flows the smoothest) solder and put more on the contact point and take your wick and press the ends towards each other until you can see light through the wick (this opens the wick to allow more solder in) if you are using a variable temp iron turn it ups all the way if not use your hottest iron and then try the wick on it it may take a few tries but it seems to work good luck

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  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2009-07-30 00:06
    Don't laugh, but this is a tried and true field repair technique from the "olden" days (although I still use it at home). Fill the hole with enough solder so that it can get a proper amount of heat flow from the iron. Get that solder nice and hot, pull the iron away quickly, and sharply blow through the hole with your mouth (no, don't make contact shocked.gif ). Also, you can heat up the solder and then tap the board on a hard surface to knock out the molten solder.

    How it works: It is very easy to blow molten solder out of a hole (or suck it out using a solder sucker as Phil mentions). The trick is, that if you wick down too much solder, heat can't transfer well, so that last little bit becomes a major pain. So, add some solder back to the hole so you can obtain a "fully molten blob" and your luck should change.

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  • VaatiVaati Posts: 712
    edited 2009-07-30 00:10
    Have you tried a desoldering braid? I use the RipoffShack one, and it does a great job at removing SRAMs from my NES... smile.gif

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  • Carl HayesCarl Hayes Posts: 841
    edited 2009-07-30 00:22
    Do one hole at a time, as follows.

    Using a small-tipped temperature-controlled soldering iron wih·a 700 or 800 degree tip, flood the pad and the hole with nice new 60/40 solder.· Then use solder wick to suck it all out.· This always works, although it may sometimes take more than one try if the particular hole is especially dirty.

    If there's a hole for which it just won't work on one side of the board, try it on the other side -- there may be debris (such as lead oxides or even ordinary dirt)·that won't pass clear through the hole.

    Not only does it work every time, but almost always the hole comes so clean that it's every bit as good as new.

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  • Lab RatLab Rat Posts: 289
    edited 2009-07-30 00:22
    Vaati said...
    ·RipoffShack
    i agree but i have some from school i grab it out of the cabinet use it and forget to put it back and it gets mixed in with my parts and eventualy comes home lol
    but i have blown the solder out of holes before i was gonna say to try that but i was already trying to im three people at once lol

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  • Lab RatLab Rat Posts: 289
    edited 2009-07-30 00:23
    also try the desoldering iron from ripoffshack it works great i had one until i modified it and broke it

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    ·
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-30 01:28
    I've never had good luck with solder wick, except for surface mount devices. The spring-loaded sucking tool sold by Radio Shack works great, however. You may need to "prime the pump" by adding solder to the hole, but it's way more effective than an exraction bulb, due to the extreme and sudden vacuum that it applies. I typically hold the board vertically in the board vise and apply the iron to one side with the sucker tip to the other. Once the solder melts, press the trigger button, and — voila! — no more solder in the hole.

    I've got an expensive electric desoldering station but more often than not rely on this little device for the stubborn jobs.

    -Phil
  • kwinnkwinn Posts: 8,697
    edited 2009-07-30 02:00
    I have to agree with Phil Pilgrim. The spring actuated solder suckers are the best hand tool for cleaning out holes. I replaced every IC (12 boards x about 40 IC's per) in an instrument that was fried by a lighting strike using a solder sucker and soldering iron. Total time to remove and replace them was about 12 hours.
  • Don MDon M Posts: 1,653
    edited 2009-07-30 12:42
    I have used this particular desoldering tool for years: http://www.hakkousa.com/detail.asp?CID=50,155&PID=838&Page=1 I have also used the spring loaded desoldering tool but find that the sudden impact from the spring sometimes causes damage to the pcb if you leave the soldering tip near the hole while using. As someone else mentioned here I too add a bit more solder (depending on the situation) before using the vacuum deoldering tool. I find it helps remove all the solder from the hole.

    Depending on the IC and tolerance of the hole I sometimes will cut the legs of the IC and then remove each leg individually from the pcb if the holes are too tight.

    One thing to remember- heat damages pcb traces just as much as it can a component. I have repaired my share of pcb's from desoldering before I finally invested in the Hakko. You can usually find them on Ebay.


    Post Edited (Don M) : 7/30/2009 12:47:37 PM GMT
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2009-07-30 14:12
    Phil Pilgrim (PhiPi) said...
    I've never had good luck with solder wick, except for surface mount devices.

    Have you done much work repairing single sided boards? That is one place where the solder wick does seem to work really well. That and removing excess solder from a surface mount device.

    For DIP components on a double sided board I usually break out the old PACE desoldering unit with the built-in vacuum pump. As it the solder is being vacuumed up I usually use the tip to wiggle the lead on the part to make sure it is free and not stuck to the edge of the hole. Once the leads are all done I usually use a small set of needle nose pliers to make sure each pin is free. You want to be careful not to damage the through hole plating within the hole. If the pin gets stuck and you pull out the part you may end up pulling out the plating in the hole! In that case you have to be very careful soldering in the new part and manually solder both sides of the part. I have an old Pinbot pinball machine that a set of lamps weren't working and the problem was someone replaced a transistor and pulled out the plating. When they soldered in the new part it was only soldered on the bottom of the board and since the solder didn't flow through the top connection was open.

    Other times if the part is trashed I cut the leads at the part. Then add some extra solder so the heat will flow through all the solder easily. Heat each pin and while the solder is molten pull out the lead with needle nose pliers. To remove the solder use a solder removal station, solder sucker, or wick.

    Robert
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