Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 1800857 times)

wch, mnementh, xrunner, Jambalaya, med6753 and 22 Guests are viewing this topic.

Offline bd139

  • Super Contributor
  • ***
  • Posts: 11517
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10950 on: May 20, 2018, 09:41:55 pm »
Nice photos as always  :-+

 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7412
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10951 on: May 20, 2018, 09:43:12 pm »
Thanks  :-+
Who let Murphy in?
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7412
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10952 on: May 20, 2018, 10:02:22 pm »
Thought you'd got yours to agree with your Agilent, that's good enough surely?

I did but that's only on 4 digit resolution. Perhaps I'm slowly turning into a voltnut :)
I really can't but help thinking is it really worth it, the 5th least significant digit is always changing anyway?
Who let Murphy in?
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7412
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10953 on: May 20, 2018, 10:08:59 pm »
I've seen many various thoughts about whether the earth on the secondary side of the 240v isolating transformer should connected to the incoming earth or left to float. Is there a real answer to this or not? 
Who let Murphy in?
 

Online KrudyZ

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10954 on: May 20, 2018, 10:17:24 pm »
I've seen many various thoughts about whether the earth on the secondary side of the 240v isolating transformer should connected to the incoming earth or left to float. Is there a real answer to this or not?

This should probably be in its own thread, but the purpose of an isolation transformer is to remove the earth reference for the line and the neutral. It is not there to remove the earth connection from a chassis.
There are exceptions to this, but you want to be careful, especially when hooking up test equipment which will likely be earthed itself.
 

Offline bd139

  • Super Contributor
  • ***
  • Posts: 11517
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10955 on: May 20, 2018, 10:27:43 pm »
Yep. There be dragons all around.

I tend not to use my isolation transformer at all preferring the one built into the DUT. If the primary side of a switcher has gone bang, all diagnostics are done 100% off line. If mains is poorly wired or exposed this is fixed before proceeding. In the case of the deadly Fluke 8000A the entire device is run off D.C. after the transformer taps on a bench supply.

My isolation transformer is a monster as well so I can’t be fucked with getting it out.  It’s an 3KVA variac with two back to back 50v transformers. Weighs about 30kg and lives in the cupboard under the stairs. Cost me £0 if I took it away which I did and it hasn’t moved for about 8 years. Plus it’s probably more dangerous than not using one.
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7412
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10956 on: May 20, 2018, 10:28:20 pm »
I've seen many various thoughts about whether the earth on the secondary side of the 240v isolating transformer should connected to the incoming earth or left to float. Is there a real answer to this or not?

This should probably be in its own thread, but the purpose of an isolation transformer is to remove the earth reference for the line and the neutral. It is not there to remove the earth connection from a chassis.
There are exceptions to this, but you want to be careful, especially when hooking up test equipment which will likely be earthed itself.
When hooking up test gear which as you rightly say, is likely to be earthed, it shouldn't be a problem surely as any voltages within the DUT are derived from a source which has no earth reference any way?
Who let Murphy in?
 

Offline bd139

  • Super Contributor
  • ***
  • Posts: 11517
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10957 on: May 20, 2018, 10:29:35 pm »
It all depends if you become a lumped element in the circuit or not  :-DD
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7412
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10958 on: May 20, 2018, 10:35:57 pm »
Yep. There be dragons all around.

I tend not to use my isolation transformer at all preferring the one built into the DUT. If the primary side of a switcher has gone bang, all diagnostics are done 100% off line. If mains is poorly wired or exposed this is fixed before proceeding. In the case of the deadly Fluke 8000A the entire device is run off D.C. after the transformer taps on a bench supply.

My isolation transformer is a monster as well so I can’t be fucked with getting it out.  It’s an 3KVA variac with two back to back 50v transformers. Weighs about 30kg and lives in the cupboard under the stairs. Cost me £0 if I took it away which I did and it hasn’t moved for about 8 years. Plus it’s probably more dangerous than not using one.
Thats a big bugger you've there, mines only a 500VA and is a straight forward 1:1 transformer which is heaps for me, if I need to vary the out I plug a small variac into it.
Who let Murphy in?
 

Offline bd139

  • Super Contributor
  • ***
  • Posts: 11517
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10959 on: May 20, 2018, 11:05:09 pm »
I can run my Henry off mine :D

I’m going to lose it when I can be bothered to dig it out. Give someone a hernia :)
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7412
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10960 on: May 20, 2018, 11:06:58 pm »
I bet its got quite an inrush when you first switch it on too.
Who let Murphy in?
 

Online mnementh

  • Super Contributor
  • ***
  • Posts: 4851
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10961 on: May 20, 2018, 11:23:43 pm »
BD139 - I never had the guts to tackle a train but always admired the brass ones, they look beautiful in natural brass and very realistic when painted. Even doing smaller stuff I found the sense of accomplishment thing a very rare occurrence compared to electronics. Finished models only numbered two to five in a good year, and then I always felt I could have done certain things better. I get a bigger buzz every time I track down an issue and fix it (still rare, but not AS rare).

Mnem- Very nice scarf join! Did that not take a lot of heat? I'm lucky the shafts on the 24XX's are plastic.... my soldering is not that good yet.
.



I used a large gun (Weller GT7 700 Degree 150W) and soldered hot & fast enough to hold the new part in my bare fingers. A bit unorthodox tactic, but it worked better for me than trying to jig it up.

Dunno about the B you're working on, but the Timebase & V/Div shafts on my 2465s aren't plastic. The inner shafts are like 2mm thick nickel/stainless, the outer sleeves are plated brass. Only the pots are plastic.

I've made a few Stirling and piston-valve external combustion engines from scratch; that's the closest I've come to building model steam locomotives.


Cheers,


mnem
*putta-putta-putta*
 
The following users thanked this post: GerryBags

Online mnementh

  • Super Contributor
  • ***
  • Posts: 4851
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10962 on: May 20, 2018, 11:30:06 pm »
It doesn't matter what any of us think; you and I both know that now that you know what the problem is, you're not going to be able to live with the 'scope (or yourself) until you either fix it properly or ship it off to some other poor bastard. Until you do it will just sit there mocking you; every moment of the day and night.  :-DD


mnem
It mocks me and I feel mocked!!!

You got that right. I hate doing something half assed. Leaving this 465 with one dead channel is definitely in that category. Now that I've slept on it I've decided come hell or high water I'm gonna fix it.

I pried the top off X100 attenuator and checked it under a magnifier. I don't see any burning or other damage. Between the 2 inner pins I measured 1.0MEG. From the inner pins to all the outer pins I measured open except one which was 10K. I assume this is OK since the schematic does not show it's inner detail. The "opens" should be the variable caps. I cleaned it in IPA. I'll gently scuff up the pins for good solder adhesion.

Don't have time today to start pulling out the vertical board. I'll definitely report back.



Of course I'm right; I wasn't telling you anything we didn't both already know. ;)


mnem
"Learning is just remembering that which you already know.
 Doing is only demonstrating that you know it.
 Teaching is only reminding others that they know as well as you.
 We are all of us learners, doers, teachers."
« Last Edit: August 30, 2019, 03:20:27 pm by mnementh »
 

Online mnementh

  • Super Contributor
  • ***
  • Posts: 4851
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10963 on: May 20, 2018, 11:48:29 pm »
You know something else we see in this video? Aside from it being a showcase of high-technology precision manufacturing, we see people... lots of them  (and interestingly, a large percentage of them women  ;)), gainfully employed, doing work that requires skill and patience. Fueling a good work ethic, and fueling the economy.

This is the precise opposite of the bean counters' goal; which is to reduce all jobs to monkey work so that skill has no value therefore demands as little pay as possible, and then if possible, to replace those monkeys with machines that require no paycheck at all.
Well you can only hope that Trumpy can get some of that manufacturing back as it's now mostly done in Asia even by the big brands and whatdoya know..... and by lots of women too.

I don't hope for anything from Resident Chump except that he ignores the things I care about. He's like penis fingers from hell on crack; everything he touches turns to shit. If we're all lucky he will actually be struck dead by lightning, and his pet turds Pence and Gorsuch right alongside him to make the trifecta. And sooner rather than later; he's trying to start WWIII.

mnem
I am Diogenes.
 

Offline Mr. Scram

  • Super Contributor
  • ***
  • Posts: 7888
  • Country: 00
  • Display aficionado
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10964 on: May 21, 2018, 01:04:14 am »
I don't hope for anything from Resident Chump except that he ignores the things I care about. He's like penis fingers from hell on crack; everything he touches turns to shit. If we're all lucky he will actually be struck dead by lightning, and his pet turds Pence and Gorsuch right alongside him to make the trifecta. And sooner rather than later; he's trying to start WWIII.

mnem
I am Diogenes.
No way the rest of the world is interested in a war. Trump can duke it out with whoever he decides is the enemy today and tell us who won. No nukesies.
 

Offline GerryBags

  • Frequent Contributor
  • **
  • Posts: 334
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10965 on: May 21, 2018, 02:42:45 am »
I don't hope for anything from Resident Chump except that he ignores the things I care about. He's like penis fingers from hell on crack; everything he touches turns to shit. If we're all lucky he will actually be struck dead by lightning, and his pet turds Pence and Gorsuch right alongside him to make the trifecta. And sooner rather than later; he's trying to start WWIII.

mnem
I am Diogenes.

 
The following users thanked this post: mnementh

Offline Brumby

  • Supporter
  • ****
  • Posts: 9208
  • Country: au
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10966 on: May 21, 2018, 06:07:17 am »
As requested by some of the members, here is a small selection of photos from the Shuttleworth evening air show Saturday 19/5/18



 :-+   :-+

There's too much vertical pagescrolling due to repeated large photos.
Ok, Sorry .... I got carried away.

Amended.
« Last Edit: May 21, 2018, 07:35:03 am by Brumby »
 

Offline tggzzz

  • Super Contributor
  • ***
  • Posts: 9842
  • Country: gb
    • Having fun doing more, with less
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10967 on: May 21, 2018, 06:42:50 am »
Caution.
There's too much politics creeping into this thread,.
There's too much vertical pagescrolling due to repeated large photos.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 
The following users thanked this post: BravoV

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7412
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10968 on: May 21, 2018, 06:52:47 am »
Caution.
There's too much politics creeping into this thread,.
There's too much vertical pagescrolling due to repeated large photos.
Could have been a lot worse if I'd not been very picky and selective because I took over 1200 photos over the 2 days and almost every single one is a "keeper" [emoji16]

Hhmm
I must be getting at this as it was not always the case..

From mobile device so predictive text might have struck again [emoji83]

Who let Murphy in?
 

Offline GerryBags

  • Frequent Contributor
  • **
  • Posts: 334
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10969 on: May 21, 2018, 07:06:36 am »
Specmaster - that's also the beauty of digital cameras. 1200 shots on a 32Gb SD card isn't a big deal, but that would have taken 34 rolls of 35mm film, say £15 each for film & processing, that's over £500! I used to assist a sports photographer back in the filmy days and you had to be fairly well assured that you'd be able to sell your shots before whacking away on the motor-drive.

Oh, and I'd say you're definitely getting good at it. Those pics are very professional looking. if you did a FB page devoted to your aerial photography I know a load of scale modellers who would go a bundle for them. Look up David Brown Photography, he does pretty nicely attending airshows and selling the shots on his website. I can't stand my brother, but he does run a high quality digital printing service in Potters Bar, just North of the M25. He'd definitely be amenable to printing and posting out your orders. Might be worth thinking about, as the actual web-space shouldn't be too pricey and you wouldn't need to stock anything.
 

Offline bd139

  • Super Contributor
  • ***
  • Posts: 11517
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10970 on: May 21, 2018, 07:07:01 am »
Have something on topic instead. This is why I like analogue scopes. This is the output of a discrete product mixer running two signals close in phase and frequency. You can see the frequency relationships here as the mixing product drifts slightly. This sort of stuff looks ugly on a digital scope.

https://youtu.be/fLNNV34M26k
 
The following users thanked this post: bitseeker

Offline tggzzz

  • Super Contributor
  • ***
  • Posts: 9842
  • Country: gb
    • Having fun doing more, with less
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10971 on: May 21, 2018, 07:23:20 am »
Caution.
There's too much politics creeping into this thread,.
There's too much vertical pagescrolling due to repeated large photos.
Could have been a lot worse if I'd not been very picky and selective because I took over 1200 photos over the 2 days and almost every single one is a "keeper" [emoji16]

Note the word "repeated"!

Quote
Hhmm
I must be getting at this as it was not always the case..

Old skiing motto: if you don't fall down 10 times a day, you aren't trying hard enough.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline Berni

  • Super Contributor
  • ***
  • Posts: 2389
  • Country: si
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10972 on: May 21, 2018, 07:40:18 am »
Have something on topic instead. This is why I like analogue scopes. This is the output of a discrete product mixer running two signals close in phase and frequency. You can see the frequency relationships here as the mixing product drifts slightly. This sort of stuff looks ugly on a digital scope.

Nice fluid motion alright.

Tho you can get pretty close if you pay enough for your digital scope. That's the reason i'm sticking to my Agilent MSO6000, so far its the most analog like digital scope i have used. Quick few second boot time, all the controls respond instantly, fast update rate(100k waveforms/s) and a display with enough resolution to make it impossible to see the pixels.
 

Offline bd139

  • Super Contributor
  • ***
  • Posts: 11517
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10973 on: May 21, 2018, 08:19:31 am »
Yep but this was £30. Many less zeroes :)

If I was running a business I’d probably hit a Keysight MSO though
« Last Edit: May 21, 2018, 08:21:23 am by bd139 »
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7412
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10974 on: May 21, 2018, 08:28:57 am »
Yep but this was £30. Many less zeroes :)

If I was running a business I’d probably hit a Keysight MSO though
I reckon that could be said for a large percentage of the people on this forum, I know that I'd love to be able to afford one. The bottom end of the DSO market just don't cut mustard in terms of display, insufficient pixels and general graphic capabilities. Yes they do have some very clever tricks etc but they also have other failings.

From mobile device so predictive text might have struck again [emoji83]

Who let Murphy in?
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf