[time-nuts] I love the smell of tantalum in the morning

paul swed paulswedb at gmail.com
Sat Nov 5 18:26:33 EDT 2016


So much information from so many that have obviously run into the smell of
a burnt part.
I do the cut the part to pieces and unsolder each leg. Also the 2 iron
approach.
The absolute goal, do not damage the board.
I have a hot air station also and much like the comments made not impressed.
I did grab a scrap board to play with as I was learning.
Since your cap looks like it already split in half 50% of the jobs done.
As everyone focuses on the soldering part. The damaged board is equally
critical.
The stuff in tantalums is nasty. I clean the whole area with alcohol. And
at times actually carve out some of the carbon if I can measure some level
of resistance from each trace to the center point.
Your problem looks simple enough Tom.
Just remember this. I hate caps. But have received some of my best
equipment because they fail for $/pound. Kind of a love hate thing.
Regards
Paul
WB8TSL

On Sat, Nov 5, 2016 at 4:37 PM, Tom Miller <tmiller11147 at verizon.net> wrote:

> I usually nibble away at the center of the part until it is two separate
> pieces. Then unsolder each piece. Clean the pads off with wick then install
> the new part.
>
> Use a good sharp pair of flush cut side cutters.
>
> Tom
>
>
> ----- Original Message ----- From: "Bob Camp" <kb8tq at n1k.org>
> To: "Tom Van Baak" <tvb at leapsecond.com>; "Discussion of precise time and
> frequency measurement" <time-nuts at febo.com>
> Sent: Saturday, November 05, 2016 4:24 PM
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
>
> Hi
>>
>> A *lot* depends on how many planes there are in that board. The weight of
>> he copper
>> also maters a bit. If there is enough thermal mass, you will need a
>> pre-heat process.
>> There are lots of ways to do it ranging from the kitchen oven to various
>> “frame and
>> lightbulb” setups and on into ever more complex heating approaches.
>>
>> If the hot tweezers / soldering iron / hot air tool does not reflow the
>> solder quickly (10 seconds
>> or less) stop. Get a pre-heat setup and try again. With proper heat you
>> should have the part
>> off in under 4 seconds. People don’t tend to use stopwatches when
>> soldering. 4 seconds is quite
>> a while on a joint. Ten seconds is pretty much forever ….
>>
>> Bob
>>
>> On Nov 5, 2016, at 3:12 PM, Tom Van Baak <tvb at LeapSecond.com> wrote:
>>>
>>> See C13 in the attached photo. I need to replace some blown caps on a
>>> few boards [1]. In one instance the cap got so hot it melted itself off the
>>> board. Quiet convenient, actually -- it acts like its own fuse -- but I
>>> don't think the 5071 designers had that clever feature in mind.
>>>
>>> Having not done SMT before, how should I do it with minimal risk to the
>>> very precious PCB. Or, what equipment should I use this as a good excuse to
>>> buy?
>>>
>>> Thanks,
>>> /tvb
>>>
>>> [0] http://www.imdb.com/title/tt0078788/quotes
>>> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
>>> <A1-mother-6.jpg>_______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>>> ailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>
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