robert.jarratt at ntlworld.com
Wed Jul 5 17:34:54 CDT 2017
> -----Original Message-----
> From: Jon Elson [mailto:elson at pico-systems.com]
> Sent: 05 July 2017 23:25
> To: rob at jarratt.me.uk; Rob Jarratt <robert.jarratt at ntlworld.com>; General
> Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
> Subject: Re: ChipQuik Troubles
> On 07/05/2017 03:42 PM, Rob Jarratt via cctalk wrote:
> > I bought some ChipQuik recently and managed to successfully remove a
> > 74LS125 with little trouble. Today I have come to trying to desolder
> > another similar sized chip, but try as I might I just cannot get it to
> > work. The ChipQuik just balls up and won't "take" to the pins. I
> > applied plenty of the flux supplied with the ChipQuik, but I wonder if I
> too much?
> The solders may be incompatible. What are you trying to do, replace a
> defective chip to make an old board work?
I *think* it may be defective, I have a replacement for it anyway.
> You DON'T need ChipQuik. If the board was soldered with lead-free solder,
> diluting the solder with PbSn solder makes it easier. If it is already
> leaded solder, then you just need a little technique. For surface mount
> use an Xacto knife under the pins, and lift them one at a time while
> with the iron. Generally, I remove as much solder as I can with solder
> then lift the pins. When one row of pins are lifted, the chip can be
flexed a few
> times and the other row of pins break off. The remaining pins can be
> with the soldering iron.
> Then, the solder can be removed with solder wick and the new chip
If all else fails I may go with this. I don't mind if the chip is damaged
during removal as I have replacements.
> For through hole chips, the safest way is to snip the pins off at the chip
> with tiny diagonal cutters, remove the body and then pick each lead out
> tweezers while heating the pad with the soldering iron. Also, with good
> desoldering tools, you can remove the chip without destroying it. The
> desolderers have a vacuum pump (or air venturi pump) and a hollow
> desoldering tip. You apply the tip to the lead for about 5 seconds, then
> the vacuum while "swirling" the tip around the component lead.
> This works amazingly well, and the parts generally fall off the board when
> leads are done, even on multi-layer boards. The solder suckers that are
> with a standard iron are FAR inferior to the units described above.
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