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 Post subject: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 2:41 pm 
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Location: Annapolis, MD
We regularly hear about someone on You Tube that has good pointers on a particular kind of repair or modification. I would guess that most of these people are simply sharing some good advice and not trying to make a living off of it.
But then we have some misguided engineering---sometimes accompanied by hype and showmanship.
And we are sometimes asked to pay for the hype....

There are a minimum of two classes of engineers to avoid:
I--the truly incompetent
II--the purveyors of "solutions in search of a problem"

In 43 years with NASA, I had many opportunities to deal with both. "Truly Incompetent" was usually relatively easy. Once this person was identified, it was relatively rare to have someone come to their defense (the natural fear of guilt by association)

Category II was always more difficult. These were usually smart and knowledgeable people with a lot of creative ideas. The issue typically was that whatever problem needed to be solved did not need a fancy solution---or there was simply not a problem to be solved at all.

In my experience, good engineers and technicians use simple and straightforward test and trouble-shooting methods. Very few problems require large amount of test equipment or special circuits. What if far more important is the that test setup needs to be appropriate for the problem at hand. Suppose, for example, we wanted to test the leakage of a capacitor. The first question might logically be: "Why are we doing this?" Most often, it was to screen parts for latent defects. For that, we would get a power supply with the right output voltage for capacitor's rating, and an appropriate current meter. OTOH, if a circuit needed a particularly low leakage current to work correctly, then we might need very sensitive low voltage measurements. A "Category II" engineer would be prone to getting these 2 scenarios confused.

Trouble-shooting and failure diagnostics does not normally require sophisticated test equipment. Almost anything you need to know can be had from the standard repertoire of scopes, voltmeters, and signal sources. To be sure, we often see special-purpose setups designed to make repetitive or complex tests more efficient. But, with just one DUT on the bench, we usually just need the basic tools.

If we look at some of the hype in places like YouTube, what comes into play is a natural human tendency to believe that fancier and more complex = better. It is very easy to fall into a mental trap that assumes that a custom testing widget can do a better job than a simple DVM or scope. We are all prone to hearing an eloquent discourse on how some widget will perform measurements to a fraction of a percent, but forgetting that the problem at hand might only require a 10% measurement.

Someone in NASA uttered a now-famous truism: "Better is the mortal enemy of Good Enough".
And well-meaning engineers promoting elegant solutions to non-existent problems were not popular. Some mended their ways, and some disappeared.

The moral: Before you embark on building clever test widgets, spend time understanding the measurements that you can do with little or NO equipment.

You can usually do "signal injection" testing with your finger. And you can usually get a "good enough" test of a 9-volt battery with your tonque........

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-Mark
"Measure voltage, but THINK current." --anon.


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 3:41 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 9999
Location: Santa Rosa, CA
Quote:
The moral: Before you embark on building clever test widgets, spend time understanding the measurements that you can do with little or NO equipment.


I have learned on this Forum, that an AA5 radio can't possibly be repaired without a room full of Tektronix test equipment, an HP VTVM, and a General Radio bridge. I feel naked with my Harbor Freight (free) DMM, which augments my "finger" signal injector.

I migrated from a TV repair shop in Chicago where we had "service" grade equipment and Heathkits. One older tech was a WW II vet who used fingers and smoke tests. Later I worked in a nicely equipped college lab and lusted for HP and TEK equipment.

I tried golf years ago and gave up. Just didn't have the knack. Friends told me that $3000 worth of clubs, new shoes, and a $500 putter would really improve my game; I didn't believe that, so I quit.

Having managed engineers at Westinghouse and Siliconix, there might be one other type of engineer. I encountered engineers who would spend an hour telling me why what I needed to get done was either impossible, impractical, or unnecessary. They weren't lazy or incompetent, but formed judgments too early and then just dug in. I also had a couple of "Wally" engineers (Dilbert cartoon) who spent a little time sleeping every day. https://i.pinimg.com/originals/20/6f/1d ... e70d07.gif

Rich


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 3:53 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
Quote:
I have learned on this Forum, that an AA5 radio can't possibly be repaired without a room full of Tektronix test equipment, an HP VTVM, and a General Radio bridge.

Don't forget the 245 lb Spectrum Analyzer and tracking generator. 8)

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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 9:47 pm 
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Joined: May Sun 13, 2012 8:12 pm
Posts: 12623
Location: Central PA 16801
I have all "the stuff". where does it sit ? up on a a few shelves either covered up or in a box.

how to I calibrate the IF of the standard tube radio ? I use a little computer fan on a switching psup wall wart. it generates a very wide broadband "buzz" and since it is on a cord, I can move it away from the set and get the buzz weak so hardly any AVC is triggered during IF alignment. I peak the buzz for maximum amplitude on my eardrums.

I have calibrated IF with the signal generator calibrated with a frequency counter, a meter across the voice coil of the speaker, and all the other yadda.

all I need is the little noise generator and my ears.

this method has proven to be just as effective if not better than using "all the stuff".

second, I am grateful to have many excellent "marker" broadcast stations 30-50 miles away on excellent frequencies like 560, 620, 900, 1020, 1400, 1450, and 1600 to do the RF alignment.

every one of my radios receive wonderfully across the band.

as for a noise generator, I use my finger on the volume control.

when I am restoring a radio or an amplifier, all I exclusively use is my meter, a fused isolation transformer, a fused variac with an ammeter, and my tube tester. everything else is up on the shelves collecting dust.

steve

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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 9:56 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 8127
Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
Dutch Rabbit wrote:
how to I calibrate the IF of the standard tube radio ? I use a little computer fan on a switching psup wall wart. it generates a very wide broadband "buzz" and since it is on a cord, I can move it away from the set and get the buzz weak so hardly any AVC is triggered during IF alignment. I peak the buzz for maximum amplitude on my eardrums.

I have calibrated IF with the signal generator calibrated with a frequency counter, a meter across the voice coil of the speaker, and all the other yadda.

all I need is the little noise generator and my ears.


If you are "peaking" I.F.'s using a noise generator, then you are NOT aligning or calibrating a radio. I have no doubt that your sets work just fine, but they are NOT aligned or calibrated. They are "peaked". There is a difference. The difference may not matter to you, and that's fine. They are yours to do with as you wish. But, they are not calibrated or aligned.

cheers


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 10:12 pm 
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Location: Central PA 16801
well, they do work just fine and rx very well.

i've done it both ways over the years and have received the same results with a lot less effort.

i was told by a very and extremely reputable member on here that in leiu of the "equipment route", it is quite an acceptable method.

:|

steve

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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 10:23 pm 
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Joined: Feb Sun 17, 2008 11:36 pm
Posts: 2022
Location: Dayton, Ohio
I used to laugh at Norm Abrams on "The New Yankee Workshop". He would say something like "now I could use a chisel and hammer to do this, but I am going to use my (a multi hundred dollar) router", etc., etc.

Electronics hobby is more fun if you like to collect a multitude of equipment, including mechanical tools, to do a better job, or, make it easier, or just more enjoyable even if you don't need it all.

Charlie


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 10:27 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 5198
Location: Sunbury, Ohio 43074
I, too, have a wall full of test equipment on my bench. I use approximately four of those devices 96% of the time.... the 2445 scope, a Fluke DMM, my DER-EE, and a little triplett handleld VOM.

This photo is older.... there are a few more doodads now.
Attachment:
fullsizeoutput_6cf.jpeg
fullsizeoutput_6cf.jpeg [ 246.89 KiB | Viewed 999 times ]

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https://www.bbtvtestequipment.com


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 10:33 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 8127
Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
Dutch Rabbit wrote:
well, they do work just fine and rx very well.

i've done it both ways over the years and have received the same results with a lot less effort.

i was told by a very and extremely reputable member on here that in leiu of the "equipment route", it is quite an acceptable method.

:|

steve


No question about the end result in terms of being able to use them. If, however you describe them, you cannot call them aligned or calibrated because that implies adjusting them to meet a set of standards and that was not done.

Don't get me wrong .... I have done the same and have used "peaked" sets with great success.

cheers


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 10:44 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 33095
Location: SoCal, 91387
I principally use just three instruments; my Fluke DMM, a B&K Transistor Analyzer for it's generator function, and a capacitance meter. I have a Heathkit signal tracer, bridge, and TRVM, but seldom use them. Sometimes I don't use any test equipment. This is usually when I am simply recapping a Transistor set, and adjusting it's IF's and RF trimmer.

AFA aligning or peaking IF's, and the antenna gang RF trimmer, I've had mixed results. Usually, but not always, using a signal generator will get the IF's in alignment and the RF peaked, which to me means obtaining the loudest audio from a given weak broadcast station during the daytime, when it's not fading.

That said, I have also simply used my ear on said station, and then did the peaking/aligning exercise again using the generator, and found absolutely no improvement. This is not always the case, but it has happened in my experience.

And to tell the truth, it's fun to align by ear, and this is a hobby for me, so I make no apologies for my method, lol.

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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 11:18 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 13152
Location: Omak,wa,usa
Hello Mark,
yes I agree with you anyway I do find a few people on youtube that really enjoy their repair videos also there are some I watch just for the enjoyment .
Equipment that use regularly is my two Flukes the 77 and 87 I also use my Sencore powerite .
Then for alignment I use my signal gen and my freq counter .
I do have a Sencore cap checker but it stopped working and Also have my Eico signal tracer and I am currently looking for a new scope .

Sincerely Rich


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Tue 02, 2019 11:35 pm 
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Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
fifties wrote:

And to tell the truth, it's fun to align by ear, and this is a hobby for me, so I make no apologies for my method, lol.


Oh, you're such a rebel! I'll bet you were a hippy in the sixties weren't ya? Grew your hair down to your ears and rode a Jawa scooter to your chess club meetings at the local coffee shop where girls in micro shorts recited poetry that didn't rhyme. LOL :)


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Wed 03, 2019 12:11 am 
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Location: SoCal, 91387
John Bartley wrote:
fifties wrote:

And to tell the truth, it's fun to align by ear, and this is a hobby for me, so I make no apologies for my method, lol.


Oh, you're such a rebel! I'll bet you were a hippy in the sixties weren't ya? Grew your hair down to your ears and rode a Jawa scooter to your chess club meetings at the local coffee shop where girls in micro shorts recited poetry that didn't rhyme. LOL :)

LMAO!
Nope, I was stationed overseas '66, 7, & 8, and about the hippest I got after rotating back was having one pair of moderately flared bell-bottoms, lol.

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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Wed 03, 2019 12:18 am 
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Location: Central PA 16801
i understand..john.

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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Wed 03, 2019 1:31 am 
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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Wed 03, 2019 1:53 am 
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Location: South Central Montana
My most used test gear is my brain.

T.


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Wed 03, 2019 3:53 am 
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Joined: Sep Tue 30, 2014 6:08 am
Posts: 4770
Location: Norfolk, VA
tinwhisker wrote:
I used to laugh at Norm Abrams on "The New Yankee Workshop". He would say something like "now I could use a chisel and hammer to do this, but I am going to use my (a multi hundred dollar) router", etc., etc.

Electronics hobby is more fun if you like to collect a multitude of equipment, including mechanical tools, to do a better job, or, make it easier, or just more enjoyable even if you don't need it all.

Charlie


IIRC, the NYW was 24 minutes in length. It'd be hard to cut a mortise and build that settee/desk/table in 24 minutes.

There's a justification for every tool in the toolbox.

Mark/Pixellany - there is also a type III - those that can, but don't, until it's time to justify their job. Opportunistic work ethics.....

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"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Wed 03, 2019 4:10 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1153
Location: Detroit, Michigan
My father maintained the radio and tv equipment in our house, and other than hand tools, the only piece of test equipment I ever saw him use was a VOM. There where occasional trips to electronics stores for parts, tubes, and Sams. Gets me wondering how much stuff I really need.


Last edited by Kevin Clark on Jul Wed 03, 2019 4:14 pm, edited 1 time in total.

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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Wed 03, 2019 5:03 am 
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Joined: Feb Sun 17, 2008 11:36 pm
Posts: 2022
Location: Dayton, Ohio
Kevin Clark wrote:
My father maintained the radio and tv equipment in our house, and other than hand tools, the only piece of test equipment I ever saw him use was a VOM. There where ocasional trips to electronics stores for parts, tubes, and Sams. Gets me wondering how much stuff I really need.


It's not necessarily what you only need but what you enjoy having on hand to use and learn through using. To repair a AAF, you don't need a distortion analyzer, but it might add to your knowledge to experiment, after repairs, what typical distortion to expect, not that you aim to do anything about it.

Charlie


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 Post subject: Re: Misguided engineering advice on You Tube
PostPosted: Jul Wed 03, 2019 5:56 am 
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Joined: Feb Fri 01, 2019 11:35 pm
Posts: 249
Location: Riverside Ca. 92504
Being relatively new to working on tube radios I experienced the urge to have all the good equipment. First it was nice meter from Harbor Freight. That was not good enough so a couple of heath kit VOMs were procured. well that led to a Simpson meter than a newer model than a spare. Then a Simpson model 467 and naturally a back up. Always need a few back ups. Signal generator, cap checker, cap checker, cap checker. Need an oscilloscope or two to help out. just got a nice Hitachi 100 meg scope. I have used the VOM twice and the Simpsons a couple of times. The cap checkers are used a lot by me. Most of the time it is the Harbor Freight meter. I need to learn how to use the rest. They look real important sitting on the shelf. I just need to stop and reread the manuals. I was in electronics in the Navy in the 60s but I have forgot a lot and equipment has changed. The newer item are a lot better. Tom


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