What Oscilloscope specs for audio work, diagnosis and repai

[Phil Allison]

"Jeff Liebermann Radio Ham FUCKHEAD & TROLL "


** Another really vile, know nothing Yank PSYCHOPATH
-------------------------------------------------------------------

You can't explain why a digital scope is not usable for analog work.

** Never said they were "unusable for analog work"

You sure are ONE vile fucking LIAR !!!

"Digital scopes absolutely SUCK for audio work."

** Clearly a very different comment - plus taken out of context.

I was genuinely
interested in WHY you thought digital scopes were unsuitable for audio
testing and troubleshooting.

** That is a BLATANT FUCKING LIE.

You are simply TROLLING like CRAZY and itching to pick a fight.

Cos you are just another sickening pile of autistic, septic SHIT.

( septic = septic tank = Aussie slang for Yank )

So, I'll try again... Why do you think digital scopes absolutely SUCK
for audio work?

** Same answer as before - CUNTHEAD !!

" There is no way to prove the point to fools like YOU by posting
messages on a newsgroup.

But anyone familiar with the use of analogue scopes for audio test and
repair work will find using a DSO to be mighty irritating and tedious - at
best.

The displayed traces on a DSO are often very misleading and hence useless
for many test procedures that analogue scopes do just perfectly. "



..... Phil

 

[N_Cook]

Jeff Liebermann <jeffl@cruzio.com> wrote in message
news:650gr5tpjk6sh4e8fpaii8rclmm9etubg9@4ax.com...

On Sun, 4 Apr 2010 12:03:59 +1000, "Phil Allison" <phil_a@tpg.com.au
wrote:

"Jeff Liebermann"
"Phil Allison"
** DO NOT BUY A DIGITAL SCOPE !!!!!!!!!!!!!

Why?

Almost any ANALOGUE scope with bandwidth of 5 MHz or more is OK -
DC
coupled or not.

Digital scopes absolutely SUCK for audio work.

Why duz it suck?

** There is no way to prove the point to fools like YOU by posting
messages on a newsgroup.

Got it. You can't explain why a digital scope is not usable for
analog work. Perhaps I can help jog your memory. See below.

Have you ever actually used a digital scope? A sound card based
scope? You really should try it some time. I think you'll be
pleasantly surprised.

Drivel: iPod Touch based sound analysis instruments:
http://www.faberacoustical.com/products/iphone/signalscope/
I'm really tempted.

Buy anyone familiar with the use of analogue scopes for audio test and
repair work will find using a DSO to be mighty irritating and tedious -
at
best.

Long ago, in my mis-spent youth, I worked in a repair shop that did
mostly audio. Not audiophile, but production line warranty repair for
various manufacturers of various audio related equipment. The lead
tech never used a scope. He would just listen to whatever was coming
out of the speakers, scribble down what stage or device was blown, and
move on to the next machine. My job was to do the unsoldering and
replacement. His batting average was about 80% correct. I couldn't
even come close to that level of accuracy, especially without a scope.
One day, I saw him try to use a scope, and fail. He didn't know how.

40+ years later, I still can't do it with audio equipment. I gotta
have my test equipment, white noise, pink noise, sweeper, distortion
analyzer, and all important oscilloscope. However, I can do something
like that with 2way radios. I've heard enough of them on the air to
be able to diagnose problems by simply listening to the audio.

Moral: Use your ears first, then use the scope.

The displayed traces on a DSO are often very misleading and hence useless
for many test procedures that analogue scopes do just perfectly.

Oh? Misleading in what way? What measurements are misleading? How
will using a digital scope produce a misleading diagnosis?

I use a digital storage scope for doing the all important square wave
test. Instead of the fuzzy blur of high frequency ringing and
oscillations seen on the analog scope, I see the digital equivalent,
which looks like a jitter infested trace in the same area (top of
leading edges). By superimposing multiple stored traces on top of
each other, ringing and oscillations are fairly obvious, even if they
exceed the frequency response and resolution accuracy of the A/D
converter.

DC related phenomenon are a problem with a PC sound card based scope.
There's no DC response, and the lower limit is about 20Hz. Low
frequency display during the square wave test will show up as a "sag"
in the horizontal part of the waveform even with a DC coupled audio
amplifier. Scope probe compensation also shows the same "sag". I
partly compensate with the scope probe compensation, and just remember
what the "sag" looks like when the scope is directly connected to the
square wave generator. In other words, I ignore the low freq sag.

High frequencies are more of a problem.
http://en.wikipedia.org/wiki/Slew_rate
Slew rate testing is difficult with a digital scope, unless the scopes
usable bandwidth is more than 5 times the highest frequency of
interest. For a 2MHz bandwidth digital scope, that limits the maximum
frequency to about 400KHz, which should be more than adequate for any
slew rate testing. That's NOT the case with bottom of the line sound
card based scopes, which are bandwidth limited to about 22KHz. The
96KHz 24bit sound cards are much better.

There are probably other areas where an analog scope is better than
digital. Tuning and tweaking in real time is much easier with a fast
responding analog scope than on a more slothish digital equivalent.
Seeing oscillations and ringing at tiny points during a frequency
sweep is somewhat easier to see on an analog scope.

Did I miss anything on why an analog scope is superior to digital?


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

After a DVM the next most useful piece of test equipment is a crystal
earpiece with a high voltage cap in tow, for audio repair work . Next comes
a sig gen and then a scope (analogue not DSO and stand alone, not tied to a
pc). Other useful pieces of test kit is a nose, eyes (with good magnifying
inspection lamp) and ears.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm

 

[David]

"K Fodder" <abc@123.com> wrote in message
news:4bb7e2f9$0$24378$c3e8da3@news.astraweb.com...

To All

Thanks for your help. Looks like I might be able to
pickup up
a tektronic 465 (100mhz) cheaply so does that sound ok or
was
there a newer 100mhz tektronic model more realible or
easier to
service? If not I'll go for it.

I'll investigate the digital option down the track.
Thanks for the other advicr given so far, I've noted it
all down.


I use a digital oscilloscope for audio all of the time.

Although the view of the waveform may be different that an
analog scope, there can be overriding benefits. Most digital
scopes have measurement functions such as frequency and
amplitude and FFT which is spectrum analysis. That is very
handy for looking at distortion if you have a very clean
audio oscillator for the source.

David

 

[Phil Allison]

"David"

I use a digital oscilloscope for audio all of the time.

** That is a blatant lie.

Although the view of the waveform may be different that an analog scope,
there can be overriding benefits.

** Nonsense.

Most digital scopes have measurement functions such as frequency and
amplitude

** So do all analogue scopes too - you bloody fool.

and FFT which is spectrum analysis. That is very handy for looking at
distortion if you have a very clean audio oscillator for the source.

** Bollocks.

FFTs fitted to typical 8 bit DSOs can barely resolve 2% harmonic levels
with any accuracy.

The crude sampled trace on such scopes makes all sine, square and other test
waveforms look distorted.



..... Phil

 

[Jeff Liebermann]

On Sun, 4 Apr 2010 09:00:56 +0100, "N_Cook" <diverse@tcp.co.uk> wrote:

After a DVM the next most useful piece of test equipment is a crystal
earpiece with a high voltage cap in tow, for audio repair work . Next comes
a sig gen and then a scope (analogue not DSO and stand alone, not tied to a
pc). Other useful pieces of test kit is a nose, eyes (with good magnifying
inspection lamp) and ears.

For me, the most useful item is a schematic. I don't have an earphone
connector on my crystal ball, but I'll certainly check with my
consulting sorcerer if it's an available option. The video on my
crystal ball is working just fine and is able to devine the future and
troubleshoot problems with amazing accuracy. However, without audio,
the best I can do is lip read and guess what's happening. I'm not
sure the other accessories will be very useful. My nose is always
dripping. My reading glasses have morphed into surgeons glasses. My
ears are fine, but haven't been the same since I bought an iPod Touch.
I do have a magnifying glass, but find a microscope more useful for
PCB work.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

On Sun, 04 Apr 2010 10:03:41 -0700, Jeff Liebermann
<jeffl@cruzio.com>wrote:

On Sun, 4 Apr 2010 09:00:56 +0100, "N_Cook" <diverse@tcp.co.uk> wrote:

After a DVM the next most useful piece of test equipment is a crystal
earpiece with a high voltage cap in tow, for audio repair work . Next comes
a sig gen and then a scope (analogue not DSO and stand alone, not tied to a
pc). Other useful pieces of test kit is a nose, eyes (with good magnifying
inspection lamp) and ears.

For me, the most useful item is a schematic. I don't have an earphone
connector on my crystal ball, but I'll certainly check with my
consulting sorcerer if it's an available option. The video on my
crystal ball is working just fine and is able to devine the future and
troubleshoot problems with amazing accuracy. However, without audio,
the best I can do is lip read and guess what's happening. I'm not
sure the other accessories will be very useful. My nose is always
dripping. My reading glasses have morphed into surgeons glasses. My
ears are fine, but haven't been the same since I bought an iPod Touch.
I do have a magnifying glass, but find a microscope more useful for
PCB work.

I just use a Dowsing Rod, points out the bad parts every time.

 

[Jeff Liebermann]

On Sun, 04 Apr 2010 13:07:46 -0400, Meat Plow wrote:

On Sun, 04 Apr 2010 10:03:41 -0700, Jeff Liebermann
jeffl@cruzio.com>wrote:

On Sun, 4 Apr 2010 09:00:56 +0100, "N_Cook" <diverse@tcp.co.uk> wrote:

After a DVM the next most useful piece of test equipment is a crystal
earpiece with a high voltage cap in tow, for audio repair work . Next comes
a sig gen and then a scope (analogue not DSO and stand alone, not tied to a
pc). Other useful pieces of test kit is a nose, eyes (with good magnifying
inspection lamp) and ears.

For me, the most useful item is a schematic. I don't have an earphone
connector on my crystal ball, but I'll certainly check with my
consulting sorcerer if it's an available option. The video on my
crystal ball is working just fine and is able to devine the future and
troubleshoot problems with amazing accuracy. However, without audio,
the best I can do is lip read and guess what's happening. I'm not
sure the other accessories will be very useful. My nose is always
dripping. My reading glasses have morphed into surgeons glasses. My
ears are fine, but haven't been the same since I bought an iPod Touch.
I do have a magnifying glass, but find a microscope more useful for
PCB work.

I just use a Dowsing Rod, points out the bad parts every time.

Dowsing only works for detecting running water, such as a leaky
electrolytic. When I tried it, the rod would always point to my
coffee cup.

The crystal ball is far better for troubleshooting. I use a form of
"map dowsing" where the schematic acts as a map. I place the
schematic behind the crystal ball, and look at the highly distorted
future image. Failed components appear as soldering iron burnt areas
or are marked by red circles, which is what I sometimes do to mark the
schematic after I finish the repair.

A crystal ball will also work by viewing the device being repaired
through the crystal ball, but it's very difficult to distinguish the
original and the future replacement parts through the distorted image.
However, viewing the device in a magic mirror, which reflects the
opposite of what will happen is very useful. The reflection will show
a smoking ruin for all the components, except the defective part,
which will look perfect.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

On Sun, 04 Apr 2010 10:39:17 -0700, Jeff Liebermann
<jeffl@cruzio.com>wrote:

On Sun, 04 Apr 2010 13:07:46 -0400, Meat Plow wrote:

On Sun, 04 Apr 2010 10:03:41 -0700, Jeff Liebermann
jeffl@cruzio.com>wrote:

On Sun, 4 Apr 2010 09:00:56 +0100, "N_Cook" <diverse@tcp.co.uk> wrote:

After a DVM the next most useful piece of test equipment is a crystal
earpiece with a high voltage cap in tow, for audio repair work . Next comes
a sig gen and then a scope (analogue not DSO and stand alone, not tied to a
pc). Other useful pieces of test kit is a nose, eyes (with good magnifying
inspection lamp) and ears.

For me, the most useful item is a schematic. I don't have an earphone
connector on my crystal ball, but I'll certainly check with my
consulting sorcerer if it's an available option. The video on my
crystal ball is working just fine and is able to devine the future and
troubleshoot problems with amazing accuracy. However, without audio,
the best I can do is lip read and guess what's happening. I'm not
sure the other accessories will be very useful. My nose is always
dripping. My reading glasses have morphed into surgeons glasses. My
ears are fine, but haven't been the same since I bought an iPod Touch.
I do have a magnifying glass, but find a microscope more useful for
PCB work.

I just use a Dowsing Rod, points out the bad parts every time.

Dowsing only works for detecting running water, such as a leaky
electrolytic. When I tried it, the rod would always point to my
coffee cup.

The crystal ball is far better for troubleshooting. I use a form of
"map dowsing" where the schematic acts as a map. I place the
schematic behind the crystal ball, and look at the highly distorted
future image. Failed components appear as soldering iron burnt areas
or are marked by red circles, which is what I sometimes do to mark the
schematic after I finish the repair.

A crystal ball will also work by viewing the device being repaired
through the crystal ball, but it's very difficult to distinguish the
original and the future replacement parts through the distorted image.
However, viewing the device in a magic mirror, which reflects the
opposite of what will happen is very useful. The reflection will show
a smoking ruin for all the components, except the defective part,
which will look perfect.

I guess I should have explained the different kinds of Dowsing Rods.
Most common those made from the same material as the dowsed parts
ie silicone, carbon, etc... Less sensitive to false positives and
detection of things like beer, coffee, vomit, etc...

I used to have a crystal ball made by Nippon Gakki but it was
unreliable and now parts are obsolete.

 

[Michael A. Terrell]

Meat, Plow wrote:

I used to have a crystal ball made by Nippon Gakki but it was
unreliable and now parts are obsolete.

Leave it to you to have obsolete balls...


--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'

 

[bob urz]

Michael A. Terrell wrote:

Meat, Plow wrote:
I used to have a crystal ball made by Nippon Gakki but it was
unreliable and now parts are obsolete.


Leave it to you to have obsolete balls...


I had a Yamaha 650 bike, but never a Yamaha glass ball......

bob

 

[Michael A. Terrell]

bob urz wrote:

Michael A. Terrell wrote:
Meat, Plow wrote:
I used to have a crystal ball made by Nippon Gakki but it was
unreliable and now parts are obsolete.


Leave it to you to have obsolete balls...


I had a Yamaha 650 bike, but never a Yamaha glass ball......

Glass balls are too fragile...


--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'

 

[Jeff Liebermann]

On Mon, 05 Apr 2010 08:06:20 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

Glass balls are too fragile...

There must be a ball shortage in Australia:
<http://www.abc.net.au/news/stories/2004/02/26/1053824.htm>

(sorry... I couldn't resist)

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Michael A. Terrell]

Jeff Liebermann wrote:

On Mon, 05 Apr 2010 08:06:20 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:

Glass balls are too fragile...

There must be a ball shortage in Australia:
http://www.abc.net.au/news/stories/2004/02/26/1053824.htm

(sorry... I couldn't resist)

In Mexico too, after that earthquake.


--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'