Test Equipment Anonymous (TEA) group therapy thread

[tggzzz]

I managed to pick up a Muirhead cell from eBay a while back.

It's a shame it wasn't the dual cell version.

It's a bit younger than yours. Last time I checked it was against my brand new Brymen 867s. The temperature adjusted voltage should have been 1.01840V and the Brymen measured it at 1.018420V which is close enough in my book!

Like this (tee hee )






My best estimate is that the indicated voltage is 0.015% lower than reality, which is in spec for the meter and cell.

[mnementh]

And now for something completely... ON TOPIC!



Just tripped over this while looking at a broken TX6150 probe being offered for far too much money: eBay auction: #132914803345

mnem
 

[med6753]

Speaking of scopes....

I mentioned the other day that the 7A24 plug-in in the 7904 showed multiple issues. Well, it's not the plug-in. The left vertical slot of the 7904 has a problem. This is the 7904 with 2 - 7A15 plug-ins. Identical settings on both plug-in's. Identical waveform. Left vertical at top. Exactly half the gain of the right vertical. So something fubar in the mainframe. I tried swapping the inputs directly to the scope's vertical amplifier and the problem stayed with the left. So the issue is somewhere in the interface between the left vertical plug-in and the scope mainframe. Diving in.....More to follow.

[med6753]

Gee....if only all fixes were that easy I'd be bored. Found the issue and it was indeed on the back plane where the plug-in and mainframe connect. PSU partially pulled out to gain access. That loop of 2 blue coaxes above the 2 with the tape were unseated to the back plane. Must have somehow happen when I pulled the PSU last week to fix it.



Here's the results. Fixed. 

[bd139]

Nice one. I love it when it's problems like that 

[med6753]

Nice one. I love it when it's problems like that 

Definitely. It looks like I have all the issues with the 7904 mainframe fixed which is a relief. That puppy is heavy and hard to jackass around. 

Looks like all that's left is clean and compensation on the 7B26 and 7B24 plug-ins. Both showing some issues with their attenuator deck switches. 

[mnementh]

Dude... haven't you learned better than to say the a-word in here? 

Murphy is gonna hunt you down and club you to death with a Tektronix Attenuator assembly if you don't stop taunting him like that... 

mnem
And I'll post video on antisocial media. 

[med6753]

Dude... haven't you learned better than to say the a-word in here? 

Murphy is gonna hunt you down and club you to death with a Tektronix Attenuator assembly if you don't stop taunting him like that... 

mnem
And I'll post video on antisocial media. 

Maybe so. And for all I know tomorrow the damn thing could burst into flames.  But right know I'm going to relish that the monster is quietly going through a burn-in and I'm going to bask in that warm Tek glow. 

[factory]

I have an 'adequate' over supply of IEC and two core leads One Milk crates worth.

These are a good thing for walls of low power TEA items too saves having to hide long leads eBay auction: #321960389520 The ones I got tested fine for insulation, current maybe not so much.

Speaking of power cables, what's a reasonable way to check the quality of unknown ones without cutting them open? I'm suspicious of most cables included with consumer equipment made in the last decade or so.

Megger of some sort for insulation 1-5kV or my recent Test and Tag box albiet it tests at 500V.

Conductor rating of anything evilbay treat it like PMPO for Audiophools divide by two divide by the square of two then halve it again as a safety margin  Or you could set up a low voltage DC load test I guess as it is easier and safety than a mains AC test. 

Over here we have special TE for that, the PAT (portable appliance testing) machine, these can do the insulation checks and older ones could also measure the earth/ground wire resistance at 20A to find out if the earth continuity meet the spec for the wire type, diameter & length. This check used to weed out a few IEC leads every year that failed with poor earth continuity. The machine also found an IEC lead with reversed polarity. 

We used to have PAT (portable appliance testing) done in house at work, since it was outsourced two out of the three companies used have turned out to be complete cowboy outfits, they never seem to turn up with the leads for checking the earth continuity and also can't be bothered with the visual inspection, hence why nothing seems to fail any-more, but they complete the "sticker test" (as I now call it) in a tenth of the time it took to do it properly. 

I too ended up with far too many IEC leads, I dumped most of the no-name ones as I got given a box of unused older Volex ones (with the unsleeved plug pins).

David

[BU508A]

 

Anyone else end up with the situation where you have more test equipment than line cords? I did. So I fixed that by buying a bunch of line cords. 

I have more line cords than test equipement. I've bought some time ago a bunch of them.
The picture below shows just a few of them as an example.



And today I received a nice parcel with more than 3kg of Rohde & Schwarz parts.
I sniped them here: https://www.ebay.de/itm/362633010637



Have to check, what all this stuff is. If someone is interested in the RF parts, please let me know. 

[worsthorse]

I got another hit from my CL WTB ad, a local ham saying he had a couple of TM plugins and frames he wanted to sell. 

When I met him today, he told me he decided to bring some other stuff, too. After going through the pile, I bought a TM502A, TM503A, three plugins, (a couple of power supplies and a DMM), two 8116As, a 6115A, and a P6046 probe, power supply, and amplifier in the original case.  The previous owner claims the P6046, 6115A and TM stuff all work, and said the 8116As "mostly worked", a position he retreated from when I mentioned error codes and custom HP ASICs. 

The whole lot cost me 110USD. So, am I an idjit, easily parted from my money? Probably, yes, even though I am expecting a 100 percent failure rate on the 8116As, the 6115, and the plugins and there's a fifty-fifty chance that the probe is junk.

But I look at it this way... I bought two 8116A lottery tickets and got four or five of the scratch off kind for free. 

That sounds like a pretty good haul to me, wch. How's the 6115A looking? I see many that have had a hard life with missing rear cover, bent fins, and scarred front panels made by gorillas chiseling off calibration stickers.

I am buried in paper of various sorts today and will post more on all this stuff once I have banished what must be banished.  The gear is generally in good shape.  The seller said the 6115A was blowing fuses but "worked before that". I will take photos of the teardown, figuring I am going to look for obvious problems then probe around for bad caps.  The good news is there is lots of 6115A experience around here and I suspect that whatever I find will have been seen before.

[grizewald]

Fancy Muirhead my pair of D-845's are smaller format https://www.eevblog.com/forum/metrology/1000-my-(hi)story-of-the-weston-cell-of-the-volt-and-of-being-a-volt-nuts/msg1437815/#msg1437815

It is a bit hard to tell but there is some sort of barrier above the Mercury and so long as you keep it and the other Electrode point with a barrier between the Cell will function so there is no need for the seconds chamber. The downside is that if that likely sintered barrier allows chemical contact over time with the Mercury it will eventually fail or block the Capillaries in the barrier. 

As tggzzz said in the other thread, the D-845 would seem to be an unsaturated cell, judging by the higher EMF. If it's still in spec after 58 years, you would appear to have something remarkable given that they are only supposed to be good for 37 years as a maximum!

I still don't understand how that Cambridge cell is constructed - time to do some research...
 

[Neomys Sapiens]

On the topic of the HP6825A - not the repair, but the manual. I did scan it in sections at 600dpi and fortunately my company has a scanner that can handle 'overlong' formats for the drawings. Then I assembled everything into a PDF using PDFcreator+. I kept that at 300dpi and enabled compression, but nevertheless it is a file of 57MB.
Where should I put it and how? My Firefox does not support KO4BB's upload via FTP. I can try IE from work.

[grizewald]

And it lives in a drop dead beautiful house!
You're a lucky guy indeed!

Thanks! It was a lucky find and it's in pretty much mint condition. It cost me all of 30 GBP.

I was frankly amazed to find a Weston cell for sale on eBay and even more surprised that the seller had no qualms about posting it from the UK to Sweden. (I certainly wasn't going to lecture him about the legality of shipping a package of distinctly harmful substances by air mail and cut myself out of the purchase!) I was quite apprehensive when I went to collect it from my local postal agent. I had visions of seeing a soaking wet package and having to reluctantly advise the guy behind the counter that he would need to close his shop and call in a hazmat team to decontaminate the place while he was at the hospital being decontaminated himself! 

Thankfully, it somehow survived the trip and after some silver polish on the terminals to remove the black oxidation and wiping down the case with a damp microfibre cloth, it was restored to its original glory. Chemically, I expected the cell to survive the trip without trouble as Muirhead incorporated a porous polythene disc in each arm of the H to keep the various chemicals in place, even during transport upside down.

I have no idea where it came from and sadly the seller didn't have the original calibration certificate. It has certainly never been abused and while it's no LTZ1000, it does seem to develop the expected EMF once adjusted for temperature, so it's still useful as an ultra low noise sanity check in the absence of a recently calibrated standard.



 

[tautech]

On the topic of the HP6825A - not the repair, but the manual. I did scan it in sections at 600dpi and fortunately my company has a scanner that can handle 'overlong' formats for the drawings. Then I assembled everything into a PDF using PDFcreator+. I kept that at 300dpi and enabled compression, but nevertheless it is a file of 57MB.
Where should I put it and how? My Firefox does not support KO4BB's upload via FTP. I can try IE from work.

A vote for Ebaman.
http://www.ebaman.com/index.php/remository

Create an account and upload.

[grizewald]

On the topic of the HP6825A - not the repair, but the manual. I did scan it in sections at 600dpi and fortunately my company has a scanner that can handle 'overlong' formats for the drawings. Then I assembled everything into a PDF using PDFcreator+. I kept that at 300dpi and enabled compression, but nevertheless it is a file of 57MB.
Where should I put it and how? My Firefox does not support KO4BB's upload via FTP. I can try IE from work.

I used the site's "upload applet", which is actually just a dynamic page, from Firefox on Linux without problems.

[tggzzz]

And it lives in a drop dead beautiful house!
You're a lucky guy indeed!

Thanks! It was a lucky find and it's in pretty much mint condition. It cost me all of 30 GBP.

I was frankly amazed to find a Weston cell for sale on eBay and even more surprised that the seller had no qualms about posting it from the UK to Sweden. (I certainly wasn't going to lecture him about the legality of shipping a package of distinctly harmful substances by air mail and cut myself out of the purchase!) I was quite apprehensive when I went to collect it from my local postal agent. I had visions of seeing a soaking wet package and having to reluctantly advise the guy behind the counter that he would need to close his shop and call in a hazmat team to decontaminate the place while he was at the hospital being decontaminated himself! 

Thankfully, it somehow survived the trip and after some silver polish on the terminals to remove the black oxidation and wiping down the case with a damp microfibre cloth, it was restored to its original glory. Chemically, I expected the cell to survive the trip without trouble as Muirhead incorporated a porous polythene disc in each arm of the H to keep the various chemicals in place, even during transport upside down.

I have no idea where it came from and sadly the seller didn't have the original calibration certificate. It has certainly never been abused and while it's no LTZ1000, it does seem to develop the expected EMF once adjusted for temperature, so it's still useful as an ultra low noise sanity check in the absence of a recently calibrated standard.

That last point is my principal use for them, apart from them merely being kewl tech.

[beanflying]

Fancy Muirhead my pair of D-845's are smaller format https://www.eevblog.com/forum/metrology/1000-my-(hi)story-of-the-weston-cell-of-the-volt-and-of-being-a-volt-nuts/msg1437815/#msg1437815

It is a bit hard to tell but there is some sort of barrier above the Mercury and so long as you keep it and the other Electrode point with a barrier between the Cell will function so there is no need for the seconds chamber. The downside is that if that likely sintered barrier allows chemical contact over time with the Mercury it will eventually fail or block the Capillaries in the barrier. 

As tggzzz said in the other thread, the D-845 would seem to be an unsaturated cell, judging by the higher EMF. If it's still in spec after 58 years, you would appear to have something remarkable given that they are only supposed to be good for 37 years as a maximum!

I still don't understand how that Cambridge cell is constructed - time to do some research...

What is clear is that the assumptions and theory as to lifetime of Weston Cells going forward in and based on the 1965 Text do not hold up to actual empirical data over time. There is a bunch of factors after manufacture that effect life let alone the actual construction of them initially. So if you have one that works treat it kind and see how it is after 100 years, as a then 75 year old I hope to be able to test it 

Re the Cambridge Photos and guesses on the construction here https://www.eevblog.com/forum/metrology/1000-my-(hi)story-of-the-weston-cell-of-the-volt-and-of-being-a-volt-nuts/msg2398591/#new

Overnight the 3DP part of the enclosure for the caseless Cell finished printing. Time for several coffees then boot the Laser into gear for the clear side clean up the print and add some fasteners.

[0culus]

All this talk about standard cells led me to reading about them, and what's apparently replaced them.

Weston cells definitely sound like "don't break it" material. About the only nastier thing I've seen is this stuff called "X-ray Fusion Flux", aka lithium tetraborate. Apparently even the hazmat crew wouldn't touch it.

Josephson standards OTOH, are much less nasty chemically.





[edit] for a real "worst of the worst" parade of the nastiest chemical compounds ever synthesized, Derek Lowe's blog is a fun read: https://blogs.sciencemag.org/pipeline/archives/2011/11/11/things_i_wont_work_with_hexanitrohexaazaisowurtzitane

[Carl_Smith]

for a real "worst of the worst" parade of the nastiest chemical compounds ever synthesized, Derek Lowe's blog is a fun read: https://blogs.sciencemag.org/pipeline/archives/2011/11/11/things_i_wont_work_with_hexanitrohexaazaisowurtzitane

Very funny post.  Especially:

Although, as the authors point out, if you heat those crystals up the two components separate out, and you’re left with crystals of pure CL-20 soaking in liquid TNT, a situation that will heighten your awareness of the fleeting nature of life.

[beanflying]

Cost of a bank of Weston Cells $1-2k, cost of a JJ Array $xxx,xxx+ ?  I won't be adding one to my Cal gear. 

The worst chemical I have ever played with is HF https://msds.orica.com/pdf/shess-en-cds-010-000034430201.pdf A company I used to work for sold and serviced Pumps for a producer of it. Plenty of other nasties we worked with as well but this one eats bones with contact among it's other issues. Barrier cream on hands, double gloves, disposable overalls, full face forced respirators ......

Chronic effects:  Chronic low dose exposure to hydrogen fluoride by inhalation can lead to ulceration and perforation of the nasal septum.  Chronic exposure to excessive quantities of gaseous or particulate fluoride results in nausea,vomiting, loss of appetite and diarrhoea or constipation.  Fluorosis or other chronic effects may result from significantacute exposures.  Hydrogen fluoride is a calcium scavenger binding with calcium in the bloodstream and bones

Mercury is a lightweight 

[mnementh]

DAMMITT, BEAN! STOP MAKING 3DP LOOK SO USEFUL!!! 

mnem
*toddles off to ded*

[0culus]

Cost of a bank of Weston Cells $1-2k, cost of a JJ Array $xxx,xxx+ ?  I won't be adding one to my Cal gear. 

The worst chemical I have ever played with is HF https://msds.orica.com/pdf/shess-en-cds-010-000034430201.pdf A company I used to work for sold and serviced Pumps for a producer of it. Plenty of other nasties we worked with as well but this one eats bones with contact among it's other issues. Barrier cream on hands, double gloves, disposable overalls, full face forced respirators ......

Chronic effects:  Chronic low dose exposure to hydrogen fluoride by inhalation can lead to ulceration and perforation of the nasal septum.  Chronic exposure to excessive quantities of gaseous or particulate fluoride results in nausea,vomiting, loss of appetite and diarrhoea or constipation.  Fluorosis or other chronic effects may result from significantacute exposures.  Hydrogen fluoride is a calcium scavenger binding with calcium in the bloodstream and bones

Mercury is a lightweight 

I see your HF and elemental mercury and raise you organic methylmercury compounds. Ordinary protective gear does not work against this stuff.  You can put as many layers of latex and creams as you want on and it'll go right through, then proceed to kill you slowly over a period of a few months.

[edit] I figured new standards cost a king's ransom ahaha

[beanflying]

Most 'interesting' job I did was supply a Hydraulic Drive Peristaltic Pump (40mm hose) with marine bronze fasteners for pumping Nitro-glycerine. 'Allegedly' it is safe providing it remains in an aqueous solution which is what we were moving. The isolated building was away from any others and surrounded by 12' high earthen barriers so I remain unconvinced. All tools in the building were also Bronze to avoid sparks 

https://goo.gl/maps/WpT6YEvaRfxu767x5

[bd139]

Cost of a bank of Weston Cells $1-2k, cost of a JJ Array $xxx,xxx+ ?  I won't be adding one to my Cal gear. 

The worst chemical I have ever played with is HF https://msds.orica.com/pdf/shess-en-cds-010-000034430201.pdf A company I used to work for sold and serviced Pumps for a producer of it. Plenty of other nasties we worked with as well but this one eats bones with contact among it's other issues. Barrier cream on hands, double gloves, disposable overalls, full face forced respirators ......

Chronic effects:  Chronic low dose exposure to hydrogen fluoride by inhalation can lead to ulceration and perforation of the nasal septum.  Chronic exposure to excessive quantities of gaseous or particulate fluoride results in nausea,vomiting, loss of appetite and diarrhoea or constipation.  Fluorosis or other chronic effects may result from significantacute exposures.  Hydrogen fluoride is a calcium scavenger binding with calcium in the bloodstream and bones

Mercury is a lightweight 

I see your HF and elemental mercury and raise you organic methylmercury compounds. Ordinary protective gear does not work against this stuff.  You can put as many layers of latex and creams as you want on and it'll go right through, then proceed to kill you slowly over a period of a few months.

[edit] I figured new standards cost a king's ransom ahaha

Yep: https://sites.dartmouth.edu/dujs/2008/05/16/remembering-karen-wetterhahn/

Death by large explosion is preferable to slow death via radiation or poisoning. I’ve lost a few eyebrows over the years to prove that.

I made a smoking machine once. That was the worst thing I have ever dealt with. Cleaning half inch thick nicotine gunk out of vacuum flasks in a lab full of smoke was not the highest point of my life.