[time-nuts] Wenzel Oscillator Repair
Magnus Danielson
magnus at rubidium.dyndns.org
Tue Jan 20 21:47:26 UTC 2009
Joseph M Gwinn skrev:
> time-nuts-bounces at febo.com wrote on 01/20/2009 04:32:15 PM:
>
>> Bruce Griffiths skrev:
>>> The relatively low thermal conductivity of the steel can will help
>>> considerably in avoiding thermal damage if the heat is
>> applied to the joint.
>>> If the can were copper it would be much more difficult to avoid
> thermal
>>> damage.
>> When I needed to have a McCoy oscillator can opened my trusty good old
>> friend Sten did the usual trick of pre-heating the can and then when
>> applying heat to the solder the thermal difference is lower and hence
> the
>> heat-flow away from the joint. Didn't take much time and I think the
>> oscillator is 100% intact.
>>
>> Pre-heating and hot air are his main tools for tricky soldering jobs. He
>
>> has low fatality rate on problems like that. This is why we let him do
>> that kind of stuff at work.
>
> I imagine that Sten works *very* fast. I've found that when soldering
> thermally sensitive things like small coil bobbins made of nylon that a
> high temperature and relatively large iron is best - the terminals come up
> to temperature almost instantly, and it's all over before the heat can
> spread and melt the bobbin.
>
> Hot air has the advantage over a flame that overtemperature is less likely
> with hot air.
Actually, the pre-heating takes a bit of time... but then it doesn't
take much effort to push the solder over to melting and it took
relatively little time. The pre-heating doesn't go all the way up there,
so melting of plastics isn't really a problem.
The pre-heating trick actually makes the big soldering iron rest most of
the time...
We have boards with so much ground/power grids that it is really a
headache to do without pre-heating, which is similar to the iron case
soldering problem.
So, doing it this way makes it go fast.
Cheers,
Magnus
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