Test Equipment Anonymous (TEA) group therapy thread

[mansaxel]

although nothing in it will sway me from my tape hate

Nothing wrong with good old audio tape. Not that I'd want it back, but it was quite practical and easy to work with.

The misery really began with the advent of the rotating head drum. That should never have been invented.

While I'm quite much more friendly towards audio tape, there still are so much inconveniences with it. As I wrote earlier; when we ran the big conversion project at ex-ex-workplace, some 6 or so digitising stations (A PR99, a DAT player, a computer with DavidSystems software, monitoring and a mixer. ), running 16 hours a day,  occupied a full-time service engineer to keep the tape machines running.

(6 suites times 2 machines makes 12 machines, times 80 hours, 960 running hours per week, divide by full-time engineer gives one service hour per 24 machine hours. Not even Windows is that bad on harddrives. )

If I'm going to say something kind about tape, it'll have to be the story about the soul music expert at that company. He started there 1978, and still works his ass off. He still interviews people using a MD21 and a Nagra IV. "You don't hold a dictaphone in front of Aretha Franklin" as he once said.

[mnementh]

"You don't hold a dictaphone in front of Aretha Franklin." as he once said...

*chest thump* Church. 

mnem
"You don't tug on Superman's cape,
you don't piss into the wind.
You don't pull the mask of the ol' Lone Ranger, and
you don't mess around with Slim..."

[Cerebus]

The "acetone slump" isn't quite that bad, usually less than 0.25mm. What can cause problems is that it rounds off all sharp corners and small details. For PLA you can get a similar effect using Ethyl Acetate, but beware, it's seriously nasty stuff and you should only use it outdoors if you want to survive the process!

McBryce.

Nothing nasty about Ethyl Acetate, it's used to flavour confectionery, as a solvent in nail polish, for decaffeinating coffee and lots of other things. Has low toxicity (Rat, oral, 5620 mg/kg*) and even smells pleasant (somewhere at the intersection of pears, apples, bananas and pineapple).

*Ethanol for comparison is 7060 mg/kg, people happily drink 40% ethanol for fun.

https://www.ehs.com/2015/04/ethyl-acetate-a-sweet-smelling-safety-hazard/

Yes, it is a byproduct and component of winemaking and natural fermentation, so would seem "more or less harmless".

However as produced for use as a solvent, it is considered highly flammable, a potent skin irritant, a safety hazard if inhaled and neurotoxic if ingested.

I'm not sure if overall it is more or less dangerous than methyl hydrate, but I certainly received plenty of flak for suggesting that as a substitute for IPA, so I'm not exactly sanguine about suggesting that ethyl acetate is "not nasty".   

mnem
 

O, c'mon, an MSDS for seawater would read like a nightmare. Ethyl Acetate is barely any more hazardous than Ethanol. Flammable? Name me a common solvent that isn't. Causes skin irritation? What doesn't, especially on an MSDS. Causes serious eye irritation? Ever had whiskey get in your eye? May cause drowsiness or dizziness? What organic solvent doesn't, potentially? Neurotoxic? You have drunk ethanol haven't you?

I get a bit tired of misinformation about chemical hazards, blowing up what small risks there are out of all proportion. People see terms like that in an MSDS and don't consider the degree of hazard that something presents. If a substance can cause any effects they will be listed in an MSDS, it does not mean that everything listed that way has significant potential for harm. MSDSs are written in such a way that the writer's lawyers can turn around and say "Our client provided you with an MSDS and you were warned of the hazards", they are produced defensively, not as neutral guides to the actual hazards involved.

You can drink ethanol, people do every day and in moderation it's harmless. Isopropanol is used to dissolve flavourings for food use and is, again, harmless in reasonable quantities. Ethyl acetate is used as food flavouring - if you've eaten anything with artificial banana or pear flavour, you've eaten it (The classic English 'pear drop' sweet is more accurately described as an Ethyl Acetate sweet). They will all be 'neurotoxic, cause drowsiness or dizziness, and eye and skin irritants' according to their MSDSs.

From a toxicity point of view I'd much rather use Ethyl Acetate as a solvent than Methanol or any chlorinated solvent. Flammability wise it's about on a par with Acetone.

To put this all into perspective, as I've already noted the LD50, oral, rat for Ethyl Acetate is 5620 mg/kg. There is a substance that if you regard Ethyl Acetate as dangerous will horrify you that has an LD50, oral, rat of 3000mg/kg making it nearly twice as potentially deadly as Ethyl Acetate. This scary substance? Na Cl, good old table salt.

[Brumby]

I'm no chemist - organic or otherwise - but I do look at the odd MSDS on occasion.  I do look at the warnings, but I also look for other information - such as typical uses.

It seems to me that ethyl acetate isn't a big deal - just don't do anything stupid like use large amounts in an enclosed space, bathe in it or light a match.

I'm all for caution - but tempered with practicality and common sense.

[xrunner]

Beware of Dyhydrogen Monoxide too! 

http://www.dhmo.org/facts.html

[Specmaster]

Yeah, I was really afraid it was permanent, caused by bleeding LCD syndrome from long-term pressure. I totes got lucky; I was not looking forward to the thought of trying to replace that LCD bonded directly to the digitizer; not even sure if I could source a replacement.

mnem
 

That was a cracking job, well done.

[Cubdriver]

The second parcel was the HP 432B I've been waiting for, here are a couple of pics, testing will have to wait till the weekend.

David

I finally opened the 432C with the Panaplex display that I mentioned last week.  It was showing NOTHING on the display; then I took the side panel off and started poking about and noticed that the display module's edge connectors seemed very short, and far from fully seated in the meter connectors.  Took it apart and pulled it out of its housing then plugged it in and lo and behold, it lights up.  The first issue is that the uppermost segment of the first full digit doesn't light.


Similar to the nixie display in the other meter, it's three boards in a 'U' shape.




However, unlike the nixie meter it appears that this version can be unfolded a bit and still work - the upper board connects to the bottom through a ribbon cable at the side rather than through the front display board as is the case with the nixie version.  This should at least make troubleshooting a bit easier.  (Need to confirm continuity of that ribbon cable, too - looks a bit on the ragged side.)


My hope is that it's something simple like a bad connection at the interface between the display board and the bottom driver board (those little wire loop things don't seem to be particularly robust), and not a dead driver chip or bad Panaplex tube.


iPhone pics for now; will take better ones with the DSLR once I actually start seriously troubleshooting it.

-Pat

[tautech]

To put this all into perspective, as I've already noted the LD50, oral, rat for Ethyl Acetate is 5620 mg/kg. There is a substance that if you regard Ethyl Acetate as dangerous will horrify you that has an LD50, oral, rat of 3000mg/kg making it nearly twice as potentially deadly as Ethyl Acetate. This scary substance? Na Cl, good old table salt.

This is so often overlooked when we look at the toxicity of the various chemicals we come into contact with throughout our lives.
LD50's give us good guidance to what we must respect however they don't tell the full story when it's best we also know what family a chemical falls into for its other side effects.

A taboo example might be the infamous Agent Orange that's made from the common 24D and 245T that on their own are reasonably innocuous hormonal herbicides however the fast tracked production of 245T allowed for the byproduct Dioxin to far exceed safe levels causing all the deformities and cancer that properly produced 245T doesn't.

If it has a warning on the label, use it with care..........

[BU508A]

Hey Vince,

look, what I've found!
Some nice R&S gear, not that expensive!   

https://www.ebay-kleinanzeigen.de/s-anzeige/rohde-schwarz-opf-videometer/1979156337-168-5586



As always: NAWTS

[Zucca]

Hey gang...

Do you think this puppy RCD/FI HAGER ADS916D



will work also with 60Hz instead of 50Hz?

I can't find a reason why it shouldn't, just want to double check...

EDIT:

all the answer are here

Yes, it should work! Thank God I got the B16.

I love Germans, they are so precise.
All the Engineers should go in Germany to study one year...

Hager absolutely top class!

[25 CPS]

Hey Vince,

look, what I've found!
Some nice R&S gear, not that expensive!   

https://www.ebay-kleinanzeigen.de/s-anzeige/rohde-schwarz-opf-videometer/1979156337-168-5586



As always: NAWTS

No!  NO!  I know what those test pulses are on it, and I want no part of it.

[25 CPS]

Alright, since we’ve all been dragged kicking and screaming into digital analogue video, here’s a Tek WFM.  NTSC for those that didn’t surmise it from the 7.5 IRE mark and other helpful hints on the graticule.  I have zero desire to look at the RF coming off the head drum and chase it through the switcher and demod and signal processing on the crappy Panasonic VHS I’ve got sitting in a shelf somewhere.   NO!  Just NO!

Who wants to do dropframe timecode calculations longhand with a pencil and paper?  Anyone?  No takers?  I thought not.

[mnementh]

https://www.ehs.com/2015/04/ethyl-acetate-a-sweet-smelling-safety-hazard/

Yes, it is a byproduct and component of winemaking and natural fermentation, so would seem "more or less harmless".

However as produced for use as a solvent, it is considered highly flammable, a potent skin irritant, a safety hazard if inhaled and neurotoxic if ingested.

I'm not sure if overall it is more or less dangerous than methyl hydrate, but I certainly received plenty of flak for suggesting that as a substitute for IPA, so I'm not exactly sanguine about suggesting that ethyl acetate is "not nasty".   

mnem
 

O, c'mon, an MSDS for seawater would read like a nightmare. Ethyl Acetate is barely any more hazardous than Ethanol. Flammable? Name me a common solvent that isn't. Causes skin irritation? What doesn't, especially on an MSDS. Causes serious eye irritation? Ever had whiskey get in your eye? May cause drowsiness or dizziness? What organic solvent doesn't, potentially? Neurotoxic? You have drunk ethanol haven't you?

I get a bit tired of misinformation about chemical hazards, blowing up what small risks there are out of all proportion. People see terms like that in an MSDS and don't consider the degree of hazard that something presents. If a substance can cause any effects they will be listed in an MSDS, it does not mean that everything listed that way has significant potential for harm. MSDSs are written in such a way that the writer's lawyers can turn around and say "Our client provided you with an MSDS and you were warned of the hazards", they are produced defensively, not as neutral guides to the actual hazards involved.

You can drink ethanol, people do every day and in moderation it's harmless. Isopropanol is used to dissolve flavourings for food use and is, again, harmless in reasonable quantities. Ethyl acetate is used as food flavouring - if you've eaten anything with artificial banana or pear flavour, you've eaten it (The classic English 'pear drop' sweet is more accurately described as an Ethyl Acetate sweet). They will all be 'neurotoxic, cause drowsiness or dizziness, and eye and skin irritants' according to their MSDSs.

From a toxicity point of view I'd much rather use Ethyl Acetate as a solvent than Methanol or any chlorinated solvent. Flammability wise it's about on a par with Acetone.

To put this all into perspective, as I've already noted the LD50, oral, rat for Ethyl Acetate is 5620 mg/kg. There is a substance that if you regard Ethyl Acetate as dangerous will horrify you that has an LD50, oral, rat of 3000mg/kg making it nearly twice as potentially deadly as Ethyl Acetate. This scary substance? Na Cl, good old table salt.

Okay... wall of text saying essentially that it is roughly as dangerous as methyl hydrate, which is pretty much exactly what I thought, and I said so.

So why is it that I get my shit jumped from multiple sides over methyl hydrate, which they sell 99.9% pure by the gallon at any hardware store, yet when you say "awwww, it's just a little dangerous..." about this stuff I'm being over-cautious?

It's like you're deliberately gaslighting me, man... I got enough  going on in my life; I don't need that kind of crap on top of it all right now.

mnem
*toddles off to nuke a Raspbian image*

[Cerebus]

https://www.ehs.com/2015/04/ethyl-acetate-a-sweet-smelling-safety-hazard/

Yes, it is a byproduct and component of winemaking and natural fermentation, so would seem "more or less harmless".

However as produced for use as a solvent, it is considered highly flammable, a potent skin irritant, a safety hazard if inhaled and neurotoxic if ingested.

I'm not sure if overall it is more or less dangerous than methyl hydrate, but I certainly received plenty of flak for suggesting that as a substitute for IPA, so I'm not exactly sanguine about suggesting that ethyl acetate is "not nasty".   

mnem
 

O, c'mon, an MSDS for seawater would read like a nightmare. Ethyl Acetate is barely any more hazardous than Ethanol. Flammable? Name me a common solvent that isn't. Causes skin irritation? What doesn't, especially on an MSDS. Causes serious eye irritation? Ever had whiskey get in your eye? May cause drowsiness or dizziness? What organic solvent doesn't, potentially? Neurotoxic? You have drunk ethanol haven't you?

I get a bit tired of misinformation about chemical hazards, blowing up what small risks there are out of all proportion. People see terms like that in an MSDS and don't consider the degree of hazard that something presents. If a substance can cause any effects they will be listed in an MSDS, it does not mean that everything listed that way has significant potential for harm. MSDSs are written in such a way that the writer's lawyers can turn around and say "Our client provided you with an MSDS and you were warned of the hazards", they are produced defensively, not as neutral guides to the actual hazards involved.

You can drink ethanol, people do every day and in moderation it's harmless. Isopropanol is used to dissolve flavourings for food use and is, again, harmless in reasonable quantities. Ethyl acetate is used as food flavouring - if you've eaten anything with artificial banana or pear flavour, you've eaten it (The classic English 'pear drop' sweet is more accurately described as an Ethyl Acetate sweet). They will all be 'neurotoxic, cause drowsiness or dizziness, and eye and skin irritants' according to their MSDSs.

From a toxicity point of view I'd much rather use Ethyl Acetate as a solvent than Methanol or any chlorinated solvent. Flammability wise it's about on a par with Acetone.

To put this all into perspective, as I've already noted the LD50, oral, rat for Ethyl Acetate is 5620 mg/kg. There is a substance that if you regard Ethyl Acetate as dangerous will horrify you that has an LD50, oral, rat of 3000mg/kg making it nearly twice as potentially deadly as Ethyl Acetate. This scary substance? Na Cl, good old table salt.

Okay... wall of text saying essentially that it is roughly as dangerous as methyl hydrate, which is pretty much exactly what I thought, and I said so.

No, that is not what I said. If you actually read it rather than dismiss it was "a wall of text" you'd know that.

Methanol is considerably more toxic than any of the other things I mentioned (apart from [some] chlorinated solvents) because the process of detoxifying it in your liver makes formaldehyde as the first detoxification step. You know, the stuff they use to pickle museum specimens and corpses. LD50, oral, rat is 56mg/kg for Methanol, so Methanol is 100 times more toxic than Ethyl Acetate, 126 times more toxic than Ethanol.

So why is it that I get my shit jumped from multiple sides over methyl hydrate, which they sell 99.9% pure by the gallon at any hardware store, yet when you say "awwww, it's just a little dangerous..." about this stuff I'm being over-cautious?

There are many things sold in hardwares stores at 99% odd purity, that doesn't make them safe. I'm sure you could get industrial sized vats of Sodium Hydroxide (lye) and concentrated Sulphuric Acid (sold as drain cleaner) in the big box stores. Just because something is on open sale doesn't make it intrinsically safe. There are probably 2000 things in every hardware store that'll kill you if you misuse them, some quickly, some slowly, and some that will hurt the whole time they are killing you. The "but they sell it everywhere" argument has about as much strength as saying of newspapers: "But they wouldn't be allowed to print it if it wasn't true".

It's like you're deliberately gaslighting me, man... I got enough  going on in my life; I don't need that kind of crap on top of it all right now.

mnem
*toddles off to nuke a Raspbian image*

You're just being paranoid, nobody is gaslighting you. Don't take a post that follows on from what you're saying as being about you and just you. And you accuse Vince of being a drama llama.

[mnementh]

K, fine. Wall of text that means exactly as much to me as what some of us said about VCRs means to Vince. Not all of us are strong with the organic chemistry; from what I could tell of what you were saying, they seemed very similar. If you'd said simply that methyl hydrate was a lot worse, I'd have known that was what you meant.

If you weren't being deliberately obtuse, great. The end result is the same: You didn't communicate what you meant to everybody in your audience.

For my part, I'll remember to ask you next time you say something in chemistry-ese that doesn't 100% make sense to me, even if I think got the gist of it.

Cheers,

mnem
*toddles off to ded*

[mansaxel]

I get a bit tired of misinformation about chemical hazards

I once trolled a "We must protect the children from CHEMICALS" mum on social media, because, well, yes, there are things that are dangerous, but as Cerebus points out, there's a MSDS and a LD50 for just about everything.

My troll?

"My children are exposed to 'Silicon Dioxide' at the daycare center"

She was, after a few back-and-forths with omnious exposure examples ("Yes, they play in it, and it goes on their skin." "Some children have eaten it." "It's on the floors and on their clothes") on the subject, ready to start some kind of campaign and getting really worked up.

I then pointed out that the SiO₂ she was worrying about, while being a CHEMICAL that does have a MSDS, also is known as "sand" and is part of the "go out and play" lifestyle not seldom favoured by parents, and that she might need to discriminate a bit between different CHEMICALS.

I was not popular. But I hope it had some effect.

On a similar vein, engineering students have at times lobbied for bans to Dihydrogen monoxide . 

[Ice-Tea]

Reminds me of this:

https://www.iflscience.com/editors-blog/56-percent-of-americans-dont-think-we-should-teach-arabic-numerals-in-school/

[ch_scr]

A wild CTI OCXO breakout board appears   
Gave the new KiCAD 6 a proper try, very impressed so far.
Also gave some thought on the output impedance of the 74HC04. It should be about 70 at 5V Vcc.
That opens two possible routes: parallel two gates for ~35 and put 15 in series,
or make it an "equal resistive splitter". For that one, each port should have ~17 in series with it's 50R source impedances.
That fits rather well in the 70R ballpark, so we split off one gate with two 18R in series onto two outputs.
Only downside is you will have to terminate both for impedances to be correct.
With an OCXO datasheet in hand, we see it expects to drive a single gate. The 74HC04 OTOH can drive five. So through one gate the signal goes,
distributes to five; two groups of two for independent 50 outputs, and the leftover one split up for a lower jitter dual out.

Gave thought to the grounding (let's see if it's a good idea): star ground for the DC, ground plane for the AC (notice ground plane cutouts on component legs).
Ignored the correct trace width for the 50 outputs for routing space concerns. Tried the new "single trace length match" feature - neat!

Prototype eagerly awaiting it's OCXO

[med6753]

Reminds me of this:

https://www.iflscience.com/editors-blog/56-percent-of-americans-dont-think-we-should-teach-arabic-numerals-in-school/

Gee, it's common knowledge that most Americans are fat due to shitty diet and dumb as a box of rocks due to failing education system. So you have to remind us of that and post this which is like hanging a huge slab of rotten smelly meat on a pole out in open. Hope you're happy and better have these handy. You're gonna need them.

Think I'll stay off the blog today.   

[Robert763]

A wild CTI OCXO breakout board appears   
Gave the new KiCAD 6 a proper try, very impressed so far.
Also gave some thought on the output impedance of the 74HC04. It should be about 70 at 5V Vcc.
That opens two possible routes: parallel two gates for ~35 and put 15 in series,
or make it an "equal resistive splitter". For that one, each port should have ~17 in series with it's 50R source impedances.
That fits rather well in the 70R ballpark, so we split off one gate with two 18R in series onto two outputs.
Only downside is you will have to terminate both for impedances to be correct.
With an OCXO datasheet in hand, we see it expects to drive a single gate. The 74HC04 OTOH can drive five. So through one gate the signal goes,
distributes to five; two groups of two for independent 50 outputs, and the leftover one split up for a lower jitter dual out.

Gave thought to the grounding (let's see if it's a good idea): star ground for the DC, ground plane for the AC (notice ground plane cutouts on component legs).
Ignored the correct trace width for the 50 outputs for routing space concerns. Tried the new "single trace length match" feature - neat!
<SNIP>

Did you consider the third option of two gates each with 30R in series with the two 100R outputs paralleled? I think this would have two benefits. First the peak and short circuit currents for eachg gate would be reduced. Secondly, but somewhat related, current spikes caused by the outputs not switching perfectly together would be reduced. Disadvantage is an extra resistor per output.
 

[Ice-Tea]

Reminds me of this:

https://www.iflscience.com/editors-blog/56-percent-of-americans-dont-think-we-should-teach-arabic-numerals-in-school/

Gee, it's common knowledge that most Americans are fat due to shitty diet and dumb as a box of rocks due to failing education system. So you have to remind us of that and post this which is like hanging a huge slab of rotten smelly meat on a pole out in open. Hope you're happy and better have these handy. You're gonna need them.

Think I'll stay off the blog today.   

For fucksake dude. As far as I am concerned the fact that Americans are the subject of that study is a pure coincidence. It was meant to illustrate people are stupid, not that Americans are stupid.

[ch_scr]

Did you consider the third option of two gates each with 30R in series with the two 100R outputs paralleled? I think this would have two benefits. First the peak and short circuit currents for eachg gate would be reduced. Secondly, but somewhat related, current spikes caused by the outputs not switching perfectly together would be reduced. Disadvantage is an extra resistor per output.

Your're right, that's the proper way to parallel gates! Put it in, two resistors more are not going to hurt.

[mnementh]

A wild CTI OCXO breakout board appears   
Gave the new KiCAD 6 a proper try, very impressed so far.  (SNIP)   Tried the new "single trace length match" feature - neat!
   Prototype eagerly awaiting it's OCXO   

That's a tasty little bit of enginerdery right there, ch_scr. 

What's your transfer process? I've done the old laser-printer toner transfer method more than a few times; I found that sometimes just rotating the image before printing does make a difference in how some details etch out, like your squiggly traces that didn't quite resolve completely.

mnem
 

[THDplusN_bad]

The second parcel was the HP 432B I've been waiting for, here are a couple of pics, testing will have to wait till the weekend.
[..]
David

[..]



[..]

-Pat

Nice one, Pat! Those Panaplex displays surely look nice.

I passionately hate these flexible connectors! The connectors in your unit show some greenish area, i.e. corroded copper?
Tektronix has used the same type of connectors in a few designs, such as in the 5B44 time base for the 5000 series oscilloscopes from the 70s. The adhesive disintegrates over time, and the conductors get exposed to the elements 

Good luck for your repair!

Cheers,

THDplusN_bad

P.S. There is a hobbyist who even makes some "Panaplexies" himself - wow - http://imajeenyus.com/vacuum/20100814_panaplex/index.shtml

[mnementh]

...There is a hobbyist who even makes some "Panaplexies" himself - wow - http://imajeenyus.com/vacuum/20100814_panaplex/index.shtml

Oooh... neat...



Sadly, it appears he hasn't followed through with the project; I don't see any updates in almost 10 years since he developed the molds/silicon substrate. The idea of a Argon Panaplex is quite tasty to me, actually.

I suspect he ran into a bit of a brick wall with current/voltage regulation as the segments were illuminated; he mentioned Argon's high drive voltage as a problem.

mnem