Test Equipment Anonymous (TEA) group therapy thread

[Saskia]

already got word from Canon that they approved my cashback request for the RP plus the RF 50/1.2L

They will wire the meagre sum of 250€ within the next 28 days ...

That brings the cost of the shard down to 749 Pesos. Will probably sell the RP later on.

Anyone interested on this side of the pond: brand new in box, full warranty, comes with EF adapter.

[mansaxel]

When I built my first reflow oven I discovered that these cheap oven probes are extremely robust and much more accurate than I was expecting:
https://www.ebay.de/itm/392275279749  I just swapped the connector at the end.

"Kein Versand nach Schweden" -- oh well. There certainly are more sellers. And I suppose polarity will be experimentally determined?

Bought a couple different ones from another China seller. Now I just need the German seller to get back to me about shipping for those NOS thermocouple connectors I've found.  This is a smaller yet fully qualified chamber of the big rabbit hole, indeed.

[mnementh]

Aircraft software is not immune despite millons being spent on verification and testing. Example a version of the 737NG Electronic Flight Instrument System (EFIS) where if one crewmember entered a certain instrument approach heading within cetain lattitude and longitude ranges ALL SIX primary flight displays go blank. Took a while to catch as there were no major airports with that runway heading in the various affected areas. 

https://www.federalregister.gov/documents/2019/12/27/2019-27966/airworthiness-directives-the-boeing-company-airplanes

   

Was that a "failure to sanitize the inputs" failure mode, or was it something more integral? Or is that still TBD?
I assume that this measure is only temporary, until the actual fault in the software is corrected...?

mnem
*seriously considers walking everywhere for the rest of his life*

I've not been able to get the details of what went wrong. Probably an overflow of some kind. The actual inputs are valid. The strange, and worrying thing is that nothing entered on one "side" should affect the other side directly. There are cross side data buses but they are not used for routine data transfer.

Okay... that is one of those "Ghost in the Machine" voodoo stories that make things like the Will Smith I, Robot scenario feel almost possible. I guess I want to believe that something this critical would be grounds to ground every aircraft that has this family of nav system in it, but there's just too much money involved. 

One thing is for sure, seeing this kind of failure in a system that has such rigid design criteria and so many layers of scrutiny before it's ever even released to the wild, and I'm sure it is but one of many... There is no way in HELL I'm going to live long enough to believe self-driving cars are by any definition of the word safe; not when there's so much more direct money pressure and so much less scrutiny and actual regulation.

mnem
Just say "No, thank you".

[tautech]

Yeah I know 



Edit: i'm still working on a 3dp version of the front panel. And I recently got some new glue I want to try out.

Some tips and guidance here:
https://www.eevblog.com/forum/testgear/restoration-of-lecroy-wavemaster-wavepro-front-bezel-by-3d-printing/

[Kosmic]

Yeah I know 



Edit: i'm still working on a 3dp version of the front panel. And I recently got some new glue I want to try out.

Some tips and guidance here:
https://www.eevblog.com/forum/testgear/restoration-of-lecroy-wavemaster-wavepro-front-bezel-by-3d-printing/

Yes I spotted this thread already, I'm planning something a bit different. I reduced the number of 3dp parts to 2 and will experiment with epoxy over PLA.

[mnementh]

   https://www.ikea.com/ca/en/p/markus-office-chair-vissle-dark-gray-90289172/

In all honesty, I'm finding it hard to beat the value of the IKEA Markus, as much as I loathe supporting the borg cubicle store... 

That's not bad for the money actually. Plus being IKEA if it cocks up you can wheel it the fuck back in and shout at them 

Bought one of these the other day for an uplighter from them: https://www.ikea.com/gb/en/p/hektar-floor-lamp-with-3-spot-dark-grey-60393603/

It might make a decent bench lamp array if you chop the base off it and come up with a suitable horizontal mounting arrangement

Yup... I did the same thing for a light in my steel shed. 

I've found the bonded leather version of the Markus ($258 + tax) used on Kijiji for $120; trying to justify that vs the new fabric-upholstered one with warranty. We'll see what the lister sez... world's not going to come to an end if I sit on this borked chair for a few more days.

mnem
 

   https://www.dunnfurniture.com.au/products/olg-metro-executive-chair-black

Just got back from picking up one of these in 95 points condition for CAD$60... it is an amazing chair, but just a bit too narrow. I need to find a way to add spacers to the arms; just a half a inch on each side should be enough. Either that, or kick it down to my son and buy something else for me. 

mnem
 

[ch_scr]

Ok, update on the PE1542. Seems my output caps had gone bad. DE5000 shows them as ~10R resistors. Seems I should not have taken the ones from the back of the storage shelf... As you can see, the unit is well designed: very compact but comes apart like this with only nuts, bolts and desoldering one wire to gain access. We'll see tomorrow what unfolds

[Specmaster]

Seriously stop spouting 'maybes' as 'reasons. Life has risks so on this application get over the 

Q1: is it a risk to yourself (->I don't care) or a risk to others (->I do care)?

Q2: is the benefit worth the possible penalty?

Q3: is there another way of avoiding the penalty?

The answer to the first question is the most important, since it trumps Q2 and Q3.

And spouting more  when it is NORMAL industry practice to use this method? Irrational spouting of ambit non specified risks without 'evidence' is just crap.

Hopefully people in industry have been trained what to do and possible hazards. I most countries there is a legal requirement to wear eye protection when carring out this kind of "normal industry practice". This risks may not be obvious to eveyone who might read this forum.

Safety is all about maybes. It's part of of my day job to think of the maybes and ensure they are mitigated against as far as reasonably practical.

Given some of the things written on this forum, I'm certain that risks wouldn't be obvious.

One of the things about professional engineers is that they consider not only how something works, but also how something fails.

So as a 'Professional Engineer' you will be giving out Safety advice about Bridge Building and Construction next too 

don't know the rules where you all are.  but 'round here a "professional engineer" is required to have a stamp and seal.

but you don't want to use that puppy unless your malpractice coverage is up to date, because when things go pear shaped even "lionel hutz" could  figure out pretty quick who gets sued.

(my ink pad dried up a long time ago)

If you get paid for any form of engineering then you're a professional engineer 

[Robert763]

But not a Professional Engineer (PE)

A PE in North America is roughly equal to a Chartered Engineer in the UK / Europe. Dependng on industry etc able to make formal determination of correctness of a design or work.

[tautech]

And this: 
https://www.eevblog.com/forum/chat/engineers-australia-membership/

[mnementh]

The requirement for all Chartered Engineers to smoke a pipe and to wear "uniform appropriate to their rank" (i.e. a tweed jacket with leather elbow patches) was dropped in the 1950s although many informally continued the practice into the 1970s. 

This is the most proper example I've seen on the Tube:



Made in 1954, and 15 years later there were no more locos made there. The comments section of course is a field day for morons praising the misogynism and lack of PPE of the day. It's better left unseen.

Here's an improper example... very much so, in nearly every way... 

mnem
 

[Brumby]

Checking the PSU will involve putting the Type 547 on it's side and I'm pretty sure I can handle that myself. I hope. 

Use a block and tackle.

[nixiefreqq]

Seriously stop spouting 'maybes' as 'reasons. Life has risks so on this application get over the 

Q1: is it a risk to yourself (->I don't care) or a risk to others (->I do care)?

Q2: is the benefit worth the possible penalty?

Q3: is there another way of avoiding the penalty?

The answer to the first question is the most important, since it trumps Q2 and Q3.

And spouting more  when it is NORMAL industry practice to use this method? Irrational spouting of ambit non specified risks without 'evidence' is just crap.

Hopefully people in industry have been trained what to do and possible hazards. I most countries there is a legal requirement to wear eye protection when carring out this kind of "normal industry practice". This risks may not be obvious to eveyone who might read this forum.

Safety is all about maybes. It's part of of my day job to think of the maybes and ensure they are mitigated against as far as reasonably practical.

Given some of the things written on this forum, I'm certain that risks wouldn't be obvious.

One of the things about professional engineers is that they consider not only how something works, but also how something fails.

So as a 'Professional Engineer' you will be giving out Safety advice about Bridge Building and Construction next too 

don't know the rules where you all are.  but 'round here a "professional engineer" is required to have a stamp and seal.

but you don't want to use that puppy unless your malpractice coverage is up to date, because when things go pear shaped even "lionel hutz" could  figure out pretty quick who gets sued.

(my ink pad dried up a long time ago)

If you get paid for any form of engineering then you're a professional engineer 

someone (can not recall who) once told me that you could only give engineering testimony in court if you were a licensed PE. 

no idea if that is true or not.  do you have to be a licensed doctor to give expert medical testimony in court?  (no idea there either.)

[xrunner]

no idea if that is true or not.  do you have to be a licensed doctor to give expert medical testimony in court?  (no idea there either.)

Who Can Be an Expert Witness?

Rules about expert witnesses are set by state and federal rules of evidence, depending on whether your case is in state or federal court.

According to the Federal Rules of Evidence, a qualified expert witness is someone who has knowledge, skill, education, experience, or training in a specialized field. These qualifications are generally also required of expert witnesses in state courts.

Under federal rules, experts must base their testimony on sufficient facts or data of the type reasonably relied upon by experts in their field, in order to help the jury understand issues that typically require specialized knowledge. While non-expert witnesses can only testify about what they've seen or heard, expert witnesses are generally allowed to give their specialized or professional opinion.

https://blogs.findlaw.com/law_and_life/2014/02/who-qualifies-as-an-expert-witness.html

[25 CPS]

Damn - you stole that!  Great score!  The HP 3562A was my 'first hit' on the TEA addiction spiral - read about it in the audio forums and decided to snag one - probably paid about $500-ish for it in 2013.



Next came the HP-A (at the time; now HPAK) mailing list which lead to the 'rescue' of a 5245L from the clockmaking nixie ghouls.  (shown here along with the now retired Leader audio generator that was creating the distorted sine wave in the spectrum above - note the flattened negative peaks.)



...and it's been an ever accelerating downhill ride from there, to the dismay of my floor joists and credit card.       

-Pat

I hear you.  Audio work was one of the main reasons why I decided to build my own bench at home and was also behind jumping on that 3562A when I saw it on eBay for just over $100 and I was able to pick it up locally.  It's been a snowball that's kept rolling since then.

There's now a 547 in my queue, too - got it along with a 561A and a bunch of plug ins in a nice Tek haul from a silent key over the past few weeks.  My concern is the HV transformer as it spent an unknown time period in a not-very-hospitable storage container that seems to have been on the damp side based on the mildew smell of many of the items that came out of there.

-Pat

I have the same concern with the HV transformer as it's a known fail point with the 547. But luckily this one has been in a dry environment. No mildew smell and it wasn't all that dirty/dusty either.

The three scopes I picked up are still in queue here too, including the 547.  They rode around in the car for a few days before getting unloaded in a hurry after the Doug Ford announcement 10 days ago and they've been sitting in the living room where I dropped them just inside the door.  There hasn't been any smell out of them which is promising.

On the 547, are the DCR and L parameters for the transformer windings known?  Also, is it known if the windings short together or if it's winding-to-core that goes short.  I'm just trying to think up some tests I can run on the transformer with an LRC meter, a multimeter, and an insulation tester before putting line voltage on them after I open them up and inspect the insides.  I was going to do that on the weekend but the weekend got away from me...again...

I'm keeping my fingers crossed that there are three good power transformers between the three 547s that are in queue here.  Hopefully nobody ended up with a dud.

[cyclin_al]

Seriously stop spouting 'maybes' as 'reasons. Life has risks so on this application get over the 

Q1: is it a risk to yourself (->I don't care) or a risk to others (->I do care)?

Q2: is the benefit worth the possible penalty?

Q3: is there another way of avoiding the penalty?

The answer to the first question is the most important, since it trumps Q2 and Q3.

And spouting more  when it is NORMAL industry practice to use this method? Irrational spouting of ambit non specified risks without 'evidence' is just crap.

Hopefully people in industry have been trained what to do and possible hazards. I most countries there is a legal requirement to wear eye protection when carring out this kind of "normal industry practice". This risks may not be obvious to eveyone who might read this forum.

Safety is all about maybes. It's part of of my day job to think of the maybes and ensure they are mitigated against as far as reasonably practical.

Given some of the things written on this forum, I'm certain that risks wouldn't be obvious.

One of the things about professional engineers is that they consider not only how something works, but also how something fails.

So as a 'Professional Engineer' you will be giving out Safety advice about Bridge Building and Construction next too 

don't know the rules where you all are.  but 'round here a "professional engineer" is required to have a stamp and seal.

but you don't want to use that puppy unless your malpractice coverage is up to date, because when things go pear shaped even "lionel hutz" could  figure out pretty quick who gets sued.

(my ink pad dried up a long time ago)

Mine is buried so deep that I am not able to find it without scheduling a search party.  Never been used, and I did not bother to even get the ink pad...

[cyclin_al]

Unfortunately, (or maybe fortunately, I dunno... ) I have a more pressing need: My wheelie chair has finally given up the ghost; so shopping a replacement. Amazing how much BS there is in this particular market ATM... 

mnem
*sensible-ish dwagon*

Recycled Aeron. Best thing I ever bought. Also loads of companies gone down the shitter at least here so they're really cheap at the moment . Maybe the same in   Canada?

I wish... nothing I could find up here less than $600-ish that wasn't an obvious fake.

In the Trailer o' Doom, I have a really good clone of the Herman Miller task chair from that series; totally cannot remember the name, but I do miss it terribly. 

mnem
 

Watch for those government auctions.  Now that everyone is working from home, there are those for whom working from home may become permanent.
Be prepared to use a technique like Tony did with the power supplies; buy the whole lot and sell the extras.

Honey, can you clear space in the living room for 50 chairs...?

[Cubdriver]

Damn - you stole that!  Great score!  The HP 3562A was my 'first hit' on the TEA addiction spiral - read about it in the audio forums and decided to snag one - probably paid about $500-ish for it in 2013.



Next came the HP-A (at the time; now HPAK) mailing list which lead to the 'rescue' of a 5245L from the clockmaking nixie ghouls.  (shown here along with the now retired Leader audio generator that was creating the distorted sine wave in the spectrum above - note the flattened negative peaks.)



...and it's been an ever accelerating downhill ride from there, to the dismay of my floor joists and credit card.       

-Pat

I hear you.  Audio work was one of the main reasons why I decided to build my own bench at home and was also behind jumping on that 3562A when I saw it on eBay for just over $100 and I was able to pick it up locally.  It's been a snowball that's kept rolling since then.

The crazy thing is that since I started with the TE collecting, I've done barely anything with the audio stuff.  Have been collecting parts, but that's it.  Some day...

There's now a 547 in my queue, too - got it along with a 561A and a bunch of plug ins in a nice Tek haul from a silent key over the past few weeks.  My concern is the HV transformer as it spent an unknown time period in a not-very-hospitable storage container that seems to have been on the damp side based on the mildew smell of many of the items that came out of there.

-Pat

I have the same concern with the HV transformer as it's a known fail point with the 547. But luckily this one has been in a dry environment. No mildew smell and it wasn't all that dirty/dusty either.

The three scopes I picked up are still in queue here too, including the 547.  They rode around in the car for a few days before getting unloaded in a hurry after the Doug Ford announcement 10 days ago and they've been sitting in the living room where I dropped them just inside the door.  There hasn't been any smell out of them which is promising.

On the 547, are the DCR and L parameters for the transformer windings known?  Also, is it known if the windings short together or if it's winding-to-core that goes short.  I'm just trying to think up some tests I can run on the transformer with an LRC meter, a multimeter, and an insulation tester before putting line voltage on them after I open them up and inspect the insides.  I was going to do that on the weekend but the weekend got away from me...again...

I'm keeping my fingers crossed that there are three good power transformers between the three 547s that are in queue here.  Hopefully nobody ended up with a dud.

I think the main power transformers are pretty much bullet proof - the Achilles heel of the 547 is the epoxy potted HV transformer.  The explanation is that it absorbs moisture and gets lossy & heats up, to the point of changing the permeability of the ferrite core, loading the oscillator down and killing the HV.  One method I've seen for keeping it operating is to replace the tube rectifiers with solid state (reduces the stress on the transformer as the filament load is thus removed), and directing a small fan on it to help cool the core.  Apparently keeping it just a few degrees cooler does the trick.  I've also found info on rewinding them, but of course with a quick search cannot find it again now - ugh! - but it is out there.  There was also a guy on the Tek list that would occasionally rewind them for people, but I'm not sure if he's still doing it.

My fingers are crossed that yours are in good nick.

-Pat

[beanflying]

Just had my Ears and Skull probed with a 'crude' Spectrum Analyser - return home to move the possible purchase of a SA three spots up the list 

First hearing test ever on my 50+ year old ears after a bit of an issue over the last month. A nice fairly flat line with a bit of drop off above 10kHz and about average for my age.

[cyclin_al]

Aircraft software is not immune dispite millons being spent on verification and testing. Example a version of the 737NG Electronic Flight Instrument System (EFIS) where if one crewmember entered a certain instrument approach heading within cetain lattitude and longitude ranges ALL SIX primary flight displays go blank. Took a while to catch as there were no major airports with that runway heading in the various affected areas. 

https://www.federalregister.gov/documents/2019/12/27/2019-27966/airworthiness-directives-the-boeing-company-airplanes

   

Was that a "failure to sanitize the inputs" failure mode, or was it something more integral? Or is that still TBD?
I assume that this measure is only temporary, until the actual fault in the software is corrected...?

mnem
*seriously considers walking everywhere for the rest of his life*

I've not been able to get the details of what went wrong. Probably an overflow of some kind. The actual inputs are valid. The strange, and worrying thing is that nothing entered on one "side" should affect the otherside directly. There are cross side data buses but they are not used for routine data transfer.

From the AD itself:

The FAA has confirmed that the faulty version of DEU software has already been removed from all airplanes conducting scheduled airline service into the affected airports. This AD is intended to address unscheduled diversions and Boeing Business Jet (BBJ) flights into the affected airports.

You might want to buy that software upgrade....

[Cubdriver]

Here is the 547 HV explanation, courtesy of Chuck Harris on the Tekscopes mailing list:

When I first started my 547 HV repair project, my scope, which had sat idle for several years before I got it, would only run for 15 minutes before the HV crashed.

After I experimented for several days, the run time kept increasing, until after a week, it ran continuously.

I thought it had cured itself, and I was done!

Well, then I got busy with something else, and the scope sat idle for a couple of months, and the process had reset to the original 15 minutes before crash.

The issue is heat induced epoxy loss, and seems to be related to moisture absorption by the epoxy.  It seems also to be related to a chemical change in the epoxy.

There is a temporary improvement when the internal heating of the transformer winding dries out the winding...  but it is only temporary.

The oscillator stops because the ferrite core is operating at a bad point in the ferrite's curves.  Its frequency is just below the frequency where core losses start to go exponential.  And, to add insult to injury, when the core heats, it approaches the Curie temperature (about 150F), which is where the ferrite ceases to be a magnetic material.  This causes the frequency to rise... which you guessed it, makes the losses rise even more.

Back in the old days, when the EHT ran at 60KHz, and beeswax was used to impregnate the winding, the HV section was right in front of the scope's fan... out in the open.  It stayed cool and breezy.

Tektronix wrecked all that when they decided to make an extended temperature range scope (647) and switched over to an epoxy varnish potting material.  They also decided to unify the HV section to fit in a plastic box... to keep it clean, and allow reuse on all of their future scopes.

The epoxy varnish, even when new, was much more lossy than the original beeswax, so the engineers lowered the frequency, and added a provision for heatsinking the transformer core.

They also started to think about using solid state rectifiers to replace the old power hungry 5642 tubes.

You can achieve an improvement by cooling the transformer, through most any means: fan, heat sink, solid state rectifiers, lowering the operating frequency, lowering the drive voltage...

Lowering the drive voltage will make it hard to see fast, low repetition rate waveforms... kind of like hobbling a race horse...

Lowering the EHT's operating frequency can be done by parallel addition of a capacitor to the  1000pf resonance capacitor C808.

Ultimately, I found that rewinding the transformer was the only sure long term solution.

We probably wouldn't have ever noticed this problem if Tek had chosen an MOPA (Master Oscillator Power Amplifier) design to drive the transformer, instead of using a modified Hartley oscillator.  It only takes a slight lowering of the feedback efficiency to reduce the oscillator's gain below unity, and make the oscillator stop.

-Chuck Harris

And a link to the thread from which it came:
https://groups.io/g/TekScopes/topic/547_scope_hv_transformer/71366871?p=

-Pat

[tautech]

Just had my Ears and Skull probed with a 'crude' Spectrum Analyser - return home to move the possible purchase of a SA three spots up the list 

First hearing test ever on my 50+ year old ears after a bit of an issue over the last month. A nice fairly flat line with a bit of drop off above 10kHz and about average for my age.

Very useful when dealing with the fairer sex. 

Yes dear, anything you say dear. 

[mnementh]

Just because you can't hear it anymore, does not mean they can't still make your eyeballs bleed... 

mnem
*toddles off to ded*

[cyclin_al]

But not a Professional Engineer (PE)

A PE in North America is roughly equal to a Chartered Engineer in the UK / Europe. Dependng on industry etc able to make formal determination of correctness of a design or work.

It is actually a bit worse than that in the GWN.
You can only call yourself an "Engineer" if you are in fact a PE.  In Ontario, at least the PEO will send a nasty letter suggesting corrective action before taking legal action against anyone who does not hold a license.  There are even distinctions between "P.Eng." and "ing." where I have not yet learned all the nuances ... and I have tried given that I am registered in one province and live in another.

The only practical benefit of registration is that my workplace insists on using the job title of Engineer ... so everyone who holds that position must be licensed.

[psykok]

Page 3562A...



1 kHz sine fundamental



1 kHz square fundamental with harmonics.

This machine was a lucky eBay score that I got for tiny money.

The 3562A is an amazing piece  of equipment and there is not actual equivalent.

The only downside is the size of this beast.

It's a nice machine for sure and I got it on eBay for not much money.  It was listed as-is but one of the pictures showed it passing the power on tests as it started up and I don't think anybody else bid on it so I got it for less than $150 Canadian.  I just wish it had a bit more dynamic range though.  I don't know if HP's later dynamic signal analyzers increased the dynamic range or what the competition from Stanford Research Systems had to offer.  Dynamic signal analyzers really seem to be a niche product that only a small number of companies had small product lines in.

Damn - you stole that!  Great score!  The HP 3562A was my 'first hit' on the TEA addiction spiral - read about it in the audio forums and decided to snag one - probably paid about $500-ish for it in 2013.



Next came the HP-A (at the time; now HPAK) mailing list which lead to the 'rescue' of a 5245L from the clockmaking nixie ghouls.  (shown here along with the now retired Leader audio generator that was creating the distorted sine wave in the spectrum above - note the flattened negative peaks.)



...and it's been an ever accelerating downhill ride from there, to the dismay of my floor joists and credit card.       

-Pat

I got mine several years ago for 300CHF, which was a bargain  at the time.
I had to repair the screen  unit: multiple bad caps and two dead transistor in the regulation part.
Apart from that it's working nicely.

To be honest I'm almost not using it because I have an Ono Sokki CF350z which I prefer  to do quick measurement.