"Hibou":
> Much more impressive is Richard Feynman's anecdote of how he fixed a
> radio set when he were a lad. From memory (I'm too lazy to look it up),

If you had, you would have seen the title "He Fixes Radios by Thinking",
and confirmed the facts as you gave them.

(This also from memory.)
--
Mark Brader | "...a paradox that threatens to sink the whole concept that
Toronto | football games can predict electoral events"
msb@vex.net | --Chris Wilson

Peter Moylan:
> The howling reminds me of another story.
>
> A telephone technician went to the home of a customer who had complained
> that the bell of her phone had stopped working. When anyone phoned her,
> the phone made no sound. "Then how do you know that anyone has called
> you?" he asked. "Because the dog howls when someone phones me", she said.

No, the story is that the phone rang (at least sometimes) *after*
the dog howled.
> Eventually he found the problem. The dog was on a chain in the back
> yard, with the end of the chain attached to a metal stake. And that
> stake had gone right through the telephone cable.

No, the story is that the stake was supposed to be the grounding
(earthing connection) for the telephone connection, but the soil
was too dry for that -- until the dog got an electric shock and
urinated on it.

Presumably it's just a story.
--
Mark Brader "In fact I am thinking of adopting a religion
Toronto that forbids the use of non-electric tools."
msb@vex.net --Theodore W. Gray

My text in this article is in the public domain.

On 05-Apr-24 6:49, Hibou wrote:
> Le 05/04/2024 à 06:30, Hibou a écrit :
>>
>> As to fault finding.... A design I inherited was a small circuit board
>> containing 11 ICs. It went into production, and one day one of these
>> boards was sent up to me because it was faulty and they couldn't fix
>> it downstairs. I found they had changed 10 out of the 11 chips trying
>> to find the fault - but when I buzzed the board, I found a broken
>> track. [...]
>
> Much more impressive is Richard Feynman's anecdote of how he fixed a
> radio set when he were a lad. From memory (I'm too lazy to look it up),
> the set would howl when warming up, then settle down and work properly.
> He walked up and down, trying to think how this could occur, and decided
> that a later stage must be warming up before an earlier one had
> stabilised. Since the valves were identical (he would've called them
> 'toobs'), he swapped them, and that cured the fault.
>
> So there it is. Go forth and find fault!
>
Easy when you can remove and reinsert components.

Whenever there were problems with Production (capital letter use with a
purpose) PCBs, were were expected to diagnose the fault and _recommend_
the repair action. i.e. we were not allowed to remove or change any
components since that might make the PCB unacceptable to the customer.

An engineer from another site was called in to look at one PCB and he
gutted the thing. He left, happy that he had 'fixed' the problem,
leaving behind a board which had to be thrown into the bin.

--
Sam Plusnet

On 05-Apr-24 11:47, J. J. Lodder wrote:
> Hibou <vpaereru-unmonitored@yahoo.com.invalid> wrote:
>
>> Le 04/04/2024 à 16:10, Snidely a écrit :
>>>
>>> But consider TV repairmen and other service techs. There's a schematic
>>> for service techs used to explain the device in this video:
>>> <URL:https://www.youtube.com/watch?v=ue-1JoJQaEg>
>>
>> Well, yes, but they have to understand only to the level that allows
>> them to find and cure faults. A designer or an engineer who modifies
>> another's design needs a much deeper understanding.
>>
>> In the UK, anyone can call himself or herself an engineer -
>> central-heating engineer and so forth - but they are mostly technicians.
>> I prefer a more Continental European definition: 'engineers' should be
>> masters of their art - especially if they're entrusted with designing
>> bridges.
>>
>> As to fault finding.... A design I inherited was a small circuit board
>> containing 11 ICs. It went into production, and one day one of these
>> boards was sent up to me because it was faulty and they couldn't fix it
>> downstairs. I found they had changed 10 out of the 11 chips trying to
>> find the fault - but when I buzzed the board, I found a broken track.
>>
>> The place was better than it sounds. It's the exceptional that sticks in
>> the mind.
>
> Indeed. The first step in fault finding
> is inspectiing the board with a good magnifyig glass.

Fair enough, but that doesn't always work on multilayer PCBs.

--
Sam Plusnet

On 05/04/24 16:49, Hibou wrote:
>
> Much more impressive is Richard Feynman's anecdote of how he fixed a
> radio set when he were a lad. From memory (I'm too lazy to look it
> up), the set would howl when warming up, then settle down and work
> properly. He walked up and down, trying to think how this could
> occur, and decided that a later stage must be warming up before an
> earlier one had stabilised. Since the valves were identical (he
> would've called them 'toobs'), he swapped them, and that cured the
> fault.

WIWAL a friend asked me to look at his radio. I opened it up, and told
him that the sound was bad because there was a tear in the speaker.

"What's a speaker?" he asked.
"It's the part where the sound comes out."
"Oh. I thought the sound came out of the radio."

--
Peter Moylan http://www.pmoylan.org
Newcastle, NSW

On 06-Apr-24 0:04, Peter Moylan wrote:
> On 05/04/24 16:49, Hibou wrote:
>>
>> Much more impressive is Richard Feynman's anecdote of how he fixed a
>>  radio set when he were a lad. From memory (I'm too lazy to look it
>> up), the set would howl when warming up, then settle down and work
>> properly. He walked up and down, trying to think how this could
>> occur, and decided that a later stage must be warming up before an
>> earlier one had stabilised. Since the valves were identical (he
>> would've called them 'toobs'), he swapped them, and that cured the
>> fault.
>
> WIWAL a friend asked me to look at his radio. I opened it up, and told
> him that the sound was bad because there was a tear in the speaker.
>
> "What's a speaker?" he asked.
> "It's the part where the sound comes out."
> "Oh. I thought the sound came out of the radio."
>
Many years back my Mother-in-Law asked me to fix their TV.
Having no tools or instruments with me other my fingers & eyes, I hinted
that this might not be fruitful, but she insisted.
She also said she knew exactly what was wrong with it.
I asked...
She replied the "The picture tube isn't working."

--
Sam Plusnet

On 06/04/24 11:07, Sam Plusnet wrote:
> On 06-Apr-24 0:04, Peter Moylan wrote:
>> On 05/04/24 16:49, Hibou wrote:
>>>
>>> Much more impressive is Richard Feynman's anecdote of how he fixed a
>>> radio set when he were a lad. From memory (I'm too lazy to look it
>>> up), the set would howl when warming up, then settle down and work
>>> properly. He walked up and down, trying to think how this could
>>> occur, and decided that a later stage must be warming up before an
>>> earlier one had stabilised. Since the valves were identical (he
>>> would've called them 'toobs'), he swapped them, and that cured the
>>> fault.
>>
>> WIWAL a friend asked me to look at his radio. I opened it up, and told
>> him that the sound was bad because there was a tear in the speaker.
>>
>> "What's a speaker?" he asked.
>> "It's the part where the sound comes out."
>> "Oh. I thought the sound came out of the radio."
>>
> Many years back my Mother-in-Law asked me to fix their TV.
> Having no tools or instruments with me other my fingers & eyes, I hinted
> that this might not be fruitful, but she insisted.
> She also said she knew exactly what was wrong with it.
> I asked...
> She replied the "The picture tube isn't working."

I was about 15 when TV came to our town. My father took advantage of
this by making and selling TV antennas. I, despite my fear of heights,
spent a lot of time on people's roofs.

One day someone said to Dad that there was a problem with their TV set.
Could he have a look at it? We walked into the room where the whole
family was watching TV. The picture was tilted by 20 to 30 degrees.
(This could happen if the yoke at the back twisted out of place.)

Dad said "Oh, yes, you have a problem. The whole picture is tilted."

The other man said "Hmm, you might be right. I never noticed that."

--
Peter Moylan http://www.pmoylan.org
Newcastle, NSW

nospam@de-ster.demon.nl (J. J. Lodder) writes:
> Peter Moylan <peter@pmoylan.org.invalid> wrote:
>> On 04/04/24 22:26, J. J. Lodder wrote:
>> > Snidely <snidely.too@gmail.com> wrote:
>> >> After serious thinking charles wrote :
>> >>> In article <uuejk5$du7$1@usenet.csail.mit.edu>, Garrett Wollman
>> >>> <wollman@hergotha.csail.mit.edu> wrote:
>>
>> >>>> The Tacoma Narrows Bridge was a suspension bridge, of course,
>> >>>> and not a cable-stayed bridge.
>> >>>
>> >>> we were shown the film of it during my Engineering degree,
>> >>> (1959-62)
>> >>
>> >> ISTR that the explanation of the resonance was, perhaps,
>> >> oversimplified in most presentations. Being a bit banger, I didn't
>> >> retain the full scope of the correction.
>> >
>> > Not just oversimplified, it is completely wrong. Resonance had
>> > nothing to do with it,
>>
>> Could you expand? I've seen the film, of course, and heard the
>> explanation, but I don't recall anything in the explanation that
>> rejected resonance as the cause.
>
> It is just flutter.
> The frequenies are not resonant with any normal mode of the structure,

It doesn't happen absent moving air, it's a forced oscillation, so it
could arguably be said that the *system* that is resonating is the
bridge *plus* the moving air. Of course, were then talking Navier-Stokes,
rather than just the wave equation, and the concept of "modes" gets a
bit more complicated.

You probably know this, but others might not, but the reason tall metal
chimneys have helical vanes (yikes, I first typed "veins") around them
is to specifically prevent these kinds of resonances. The eddies that
cause the stall and the start of opposing eddies which then return the
favour simply can't form.

Apropos of nothing apart from frequencies, I encountered this earlier
today, and found it quite cute:
http://youtu.be/-T1tMQaZCtw - /Logistic Map Orbits/

Phil
--
We are no longer hunters and nomads. No longer awed and frightened, as we have
gained some understanding of the world in which we live. As such, we can cast
aside childish remnants from the dawn of our civilization.
-- NotSanguine on SoylentNews, after Eugen Weber in /The Western Tradition/

Phil Carmody <pc+usenet@asdf.org> wrote:

> nospam@de-ster.demon.nl (J. J. Lodder) writes:
> > Peter Moylan <peter@pmoylan.org.invalid> wrote:
> >> On 04/04/24 22:26, J. J. Lodder wrote:
> >> > Snidely <snidely.too@gmail.com> wrote:
> >> >> After serious thinking charles wrote :
> >> >>> In article <uuejk5$du7$1@usenet.csail.mit.edu>, Garrett Wollman
> >> >>> <wollman@hergotha.csail.mit.edu> wrote:
> >>
> >> >>>> The Tacoma Narrows Bridge was a suspension bridge, of course,
> >> >>>> and not a cable-stayed bridge.
> >> >>>
> >> >>> we were shown the film of it during my Engineering degree,
> >> >>> (1959-62)
> >> >>
> >> >> ISTR that the explanation of the resonance was, perhaps,
> >> >> oversimplified in most presentations. Being a bit banger, I didn't
> >> >> retain the full scope of the correction.
> >> >
> >> > Not just oversimplified, it is completely wrong. Resonance had
> >> > nothing to do with it,
> >>
> >> Could you expand? I've seen the film, of course, and heard the
> >> explanation, but I don't recall anything in the explanation that
> >> rejected resonance as the cause.
> >
> > It is just flutter.
> > The frequenies are not resonant with any normal mode of the structure,
>
> It doesn't happen absent moving air, it's a forced oscillation, so it
> could arguably be said that the *system* that is resonating is the
> bridge *plus* the moving air. Of course, were then talking Navier-Stokes,
> rather than just the wave equation, and the concept of "modes" gets a
> bit more complicated.

This is a matter of usage, really.
With your enlarged definition everything can be said to be a resonance,
which make the definition rather pointless.
It makes sense to restrict resonance to oscilations
at some natural frequency of the system that is being driven.
Thus an aeolian harp has wind-driven resonances,
a fluttering flag has not.

> You probably know this, but others might not, but the reason tall metal
> chimneys have helical vanes (yikes, I first typed "veins") around them
> is to specifically prevent these kinds of resonances. The eddies that
> cause the stall and the start of opposing eddies which then return the
> favour simply can't form.

Yet Nature is always more clever.
FYA, there was the case of the Erasmus Bridge, Rotterdam. (aka The Swan)
Find a picture of it and you will see why.
As a stayed bridge is an obvious candidate for an aeolian harp,
and all the ingenuity of the designers, with some help
from the brains at Delft Technical University was employed
to make resonances impossible.
All went well, for some time,
but at one very rainy afternoon with strong and steady steady winds
the 'strings' started to vibrate with amplitudes
up to one meter. The bridge had to be closed.
You may try to guess what had gone wrong before reading on, [1]

Jan

[1] Gur jngre ehaavat qbja gur fgevatf punatrq gur cebsvyr naq gur
rssrpgvir znff, znxvat erfbanapr cbffvoyr. Fbzr vagrepbaarpgvbaf naq
fbzr qnzcref pherq gur ceboyrz.

> Apropos of nothing apart from frequencies, I encountered this earlier
> today, and found it quite cute:
> http://youtu.be/-T1tMQaZCtw - /Logistic Map Orbits/
>
> Phil

On 2024-04-05 17:04, Peter Moylan wrote:
> On 05/04/24 16:49, Hibou wrote:
>>
>> Much more impressive is Richard Feynman's anecdote of how he fixed a
>>  radio set when he were a lad. From memory (I'm too lazy to look it
>> up), the set would howl when warming up, then settle down and work
>> properly. He walked up and down, trying to think how this could
>> occur, and decided that a later stage must be warming up before an
>> earlier one had stabilised. Since the valves were identical (he
>> would've called them 'toobs'), he swapped them, and that cured the
>> fault.
>
> WIWAL a friend asked me to look at his radio. I opened it up, and told
> him that the sound was bad because there was a tear in the speaker.
>
> "What's a speaker?" he asked.
> "It's the part where the sound comes out."
> "Oh. I thought the sound came out of the radio."

A sister-in-law phoned a few weeks ago, and asked if I could help with
her computers. She said "The CD-ROM won't turn on". I asked what she
meant, and she said that it just wouldn't turn on. I asked if she meant
that when she pressed the button the tray didn't come out. She said it
wouldn't even turn on.

After a little more back and forth, I realized that she was talking
about the main computer. She had no idea it was anything more than
something to run CD-ROMs.

Turned out to be a loose power cord that had been hit by a vacuum
cleaner nozzle.

--
The following is only a sig.
The preceding is only a disclaimer.

lar3ryca wrote:

> A sister-in-law phoned a few weeks ago, and asked if I could help with
> her computers. She said "The CD-ROM won't turn on". I asked what she
> meant, and she said that it just wouldn't turn on. I asked if she meant
> that when she pressed the button the tray didn't come out. She said it
> wouldn't even turn on.

I once read a webpage where support people told what they had
experienced. One of them had had a complaint from a customer that the
cup holder was broken. It took him a while to realize what had happened,
and then he and his collegues had to stifle a laughter.

Vg jnf gur pq-ebz genl gung jnf oebxra.

--
Bertel
Kolt, Denmark

On 16/04/24 15:36, lar3ryca wrote:

> A sister-in-law phoned a few weeks ago, and asked if I could help
> with her computers. She said "The CD-ROM won't turn on". I asked
> what she meant, and she said that it just wouldn't turn on. I asked
> if she meant that when she pressed the button the tray didn't come
> out. She said it wouldn't even turn on.
>
> After a little more back and forth, I realized that she was talking
> about the main computer. She had no idea it was anything more than
> something to run CD-ROMs.
>
> Turned out to be a loose power cord that had been hit by a vacuum
> cleaner nozzle.

When our department got its very own minicomputer (now, that's going
back many years), my phone number was on the computer room notice board
as the one to call in case of breakdown. That turned out to be a bad
thing for me, because of the many calls I got at 3 a.m. to say that the
computer wasn't working. The first few times I drove to the university
to tackle the problem. After that I did diagnosis by phone. (But still
lost sleep.)

The most common problem, it turned out, was "the printer isn't
working". I learnt to ask "Is the power turned on?" Usually the printer
power cord wasn't even plugged in.

The second-most common problem: the complaint "The computer isn't
working" turned out to mean "My program is crashing". I had to insist
very firmly that errors in their program were their problem, not mine.

--
Peter Moylan http://www.pmoylan.org
Newcastle, NSW

lar3ryca wrote:
...

> A sister-in-law phoned a few weeks ago, and asked if I could help with
> her computers. She said "The CD-ROM won't turn on". I asked what she
> meant, and she said that it just wouldn't turn on. I asked if she meant
> that when she pressed the button the tray didn't come out. She said it
> wouldn't even turn on.

> After a little more back and forth, I realized that she was talking
> about the main computer. She had no idea it was anything more than
> something to run CD-ROMs.
...

That's new to me, but I do know someone who used to refer to the main
computer as "the hard drive".

--
Jerry Friedman