Re: Shock Info

On 30 May 2007 03:32:18 -0700, teemukyttala@xxxxxxxxx wrote:

I asked it so that the question would get out and an explanation (of
sorts) would be provided. Sometimes 'loaded questions' get asked to do
just that.

Well... I guess you got your answer too. ;-)

Telling folks to do research is a great idea; how many will do it? This
is a safety issue, I think, and background information is appreciated;
denigrating anyone for asking questions doesn't help anyone.

Sorry if I made you feel denigrated but like you say yourself, this
*is* a safety issue and you don't want to kid around with those. When
it comes to issues like this I sincerely hope that people do indeed
take time to do research instead of regarding an unmoderated newsgroup
or internet site as their first source of information. After all, it's
their life on the line - and they might ruin their equipment with
wrong procedures as well.

This is not alt.guitar.amps.experts.only. There are some folks here
who would have everyone "go to school" for every answer found in "any
respected book about electronics theory". Do you suppose that the
previous poster who mentioned installing such resistors on B+ used your
table?

No. But on the other hand, he didn't ask how long this procedure would
take either so I figure that he knew what he was doing already. While
I was in school and attended few electronics courses the capacitor
charge/discharge theory was the second thing thought after Ohm's and
Kirchhoff's laws. I have also read a few books about electronics
theory during my life and it's about the same thing in most of them as
well. If these fundamentals seem unfamiliar you should really think
whether it's best practice to go to an unmoderated newsgroup to ask
basic questions or read a good book or attend some courses.

This newsgroup has meny intelligent and skillfull readers/posters so
it can teach a lot - but in my opinion, it's better to try to learn
the basic stuff from some other source.
Since not many places are offering tube electronics based
courses anymore, the logical place to learn this is by reading and
asking questions about it to techs that know what they are talking
about,for the most part. I have gotten several good tidbits from this
thread myself as well as several reminders to be careful with caps.
And I cannot understand where reading here, from experienced techs,
is any worse for learning than reading from the "Red Book' if it even
covers it! The people here have shown me much knowledge and many
"tricks" that have saved me hunderds of hours of trying to decypher
some tech writers scribble about the same subject.
And a "simple" website version instills the desire to find out more
information because of the inherent dangers mentioned in getting
shocked. So all knowledge is still the road to knowing IMHO. And with
this group, you are going to get mostly good information if you wait
long enough and read all of the answers.
And basic stuff can be learned here as well as from the 150 booklet
1961 electronics course I am presently reading. I get the added bonus
of experienced techs knowledge as well as the "tricks" of the trade.
You might remember that not everyone lives a mile from the train depot
in N.J. and can be apprentices with someone like R.K. And from what I
can comprehend, that apprenticeship is where most of this is learned
in the real world, not in some class room...


Also, if you study the concerned issue you will learn that in reality
there is no scenario where you discharge one ideal capacitor through
the bleeder resistor. You most likely have several capacitors in
parallel - some of them separated with resistors - and the math starts
to get really complex. At that point you generally don't even need the
math. Usually the required practice is to discharge capacitors in
several different locations and monitor the voltage levels with
multimeter. The discharge process may also be disturbed by dielectric
absorption/soakage/capacitor memory - whatever you want to call it -
so the only way to know for certain is again monitoring with
multimeter. I'm not an expert in this but I recall that effect of
soakage is lesser if the capacitors are discharged slowly, thus I
mentioned the thing in the warning about screwdriver method.

In practice, the only important thing you need to remember about
discharge theory is that the discharge/charge curve is logarithmic in
nature and that larger capacitance and larger resistance mean a longer
time constant - or vice versa. It is also shown by the equation. So yo
see, asking a question about discharge time is a bit vain. Yep, I
don't use the table either.

Sorry for the long (and possibly petulant) response, and by the way,
thanks for the information

You are welcome.
.

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