Test Equipment Anonymous (TEA) group therapy thread

[Neomys Sapiens]

Anyone ever seen one of these cute HP 970A handheld DMM from 1973?

https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1973-11.pdf

Yes, I saw it on Ebay at least once.
And I think there is a related model which was intended as a desk meter, but with a display of similar type on the probe.

[TorinoFermic]

Well, I found this 34401A with prepaid import for $320 plus around $100 of shipping and duties. Good enough ?

eBay auction: #164228802874

[Saskia]

with all this hubbub around floating scopes:
pardon my ignorance, but is this not the reason why differential high voltage probes were invented ?
Or: is there any reason to float the scopes if you have a diff probe sitting around ?

Or: if I work on a SMPS, would it be the right thing to just use the HV diff probe and not fuck around with any ground to earth leads ?

Or am I missing a bit here ?

[bd139]

Nope that’s exactly it.

Other option is to float the SMPS with an isolation transformer.

Edit: just swapped a half used crate of abbots ale for a 2014 22” iMac. Win. Now to find a victim and buy two crates of abbots ale and a curry. 

[tggzzz]

with all this hubbub around floating scopes:
pardon my ignorance, but is this not the reason why differential high voltage probes were invented ?
Or: is there any reason to float the scopes if you have a diff probe sitting around ?

Or: if I work on a SMPS, would it be the right thing to just use the HV diff probe and not fuck around with any ground to earth leads ?

Or am I missing a bit here ?

There may be a few infrequent edge cases, but fundamentally you are correct.

The problem is that people think of probes as bits of wire, an afterthought, and don't understand the different types and why they exist.

Having said that HV diff probes are relatively slow, and expensive, and there is the CMRR to understand.

[mnementh]

FFS people... give poor Brumby a gawddamn break.

He didn't do it; some other asshole did and he came in here ASKING WHY someone might have done.      Furthermore, he has stated pretty clearly that he had no intention of using it that way, AND he has since repaired the ground fault.

Odds are this wasn't even intentionally floated, but rather the product of some simian would-be sparky who wanted to either use the scope powered from a ungrounded outlet or who just cobbled on what-the-fuckever plug he had lying around. 

mnem
Are we REALLY THAT BORED in here...?   

[tggzzz]

Nope that’s exactly it.

Other option is to float the SMPS with an isolation transformer.

Edit: just swapped a half used crate of abbots ale for a 2014 22” iMac. Win. Now to find a victim and buy two crates of abbots ale and a curry. 

"Used Abbots ale, one previous owner" makes me think of the Lapland shamen who use fly agarics recreationally. So do their acolytes, second hand.

Apart from that unpleasant thought, you'd have to bribe me with far more than that for my working M0001AP

[bd139]

Nope that’s exactly it.

Other option is to float the SMPS with an isolation transformer.

Edit: just swapped a half used crate of abbots ale for a 2014 22” iMac. Win. Now to find a victim and buy two crates of abbots ale and a curry. 

"Used Abbots ale, one previous owner" makes me think of the Lapland shamen who use fly agarics recreationally. So do their acolytes, second hand.

Apart from that unpleasant thought, you'd have to bribe me with far more than that for my working M0001AP

Unfortunately abbots doesn’t work passively. Actually that reminds me of an ex GF I had who was perpetually stoned. Think I probably was as well. The one that had a pet fox that stank.

That’s a proper Mac though. This one is a PC with an Apple logo on it.

[mnementh]

Yeah, Apple definitely improved the breed with that paradigm shift (to X86 architecture).    Not so sure about the next one; they're seriously going ARM here in the future. 

mnem
 EDITED to clarify. I don't know that it's possible to improve the breed of either a) perpetually stoned GF or 2) stinky fox.   

[tonyalbus]

crap... could not fix it today.... but at least.. it being a part unit i got it to switch on.. ;-)

[bd139]

Yeah, they definitely improved the breed with that paradigm shift.    Not so sure about the next one; they're seriously going ARM here in the future. 

mnem
 

Yep 100%. ARM vendors have some seriously fast shit out there. The AWS Graviton2 instances for example are faster across the board than the AMD EPYC parts (!). Apple are 5 years ahead of amazon on cores as well.

Edit: to note my first proper desktop PC was an ARM based one and it was shitting on things with another zero on the end of the price tag at the time.

Edit 2: also windows is going that way as well: https://docs.microsoft.com/en-us/windows/uwp/porting/apps-on-arm

[mnementh]

Hmmm... we'll see. They're going to have to completely craft a new HAL and memory architecture to be able to use current state-of-the-art GPUs and maintain compatibility with all the I/O and accessories out in the wild for the last decade or more.

This compatibility was part of their skyrocketing popularity that everybody has started to take for granted since they went X86; take that away and the brand will quickly develop their own variant of "Ballmer-Leprosy" like when Microsoft first got into the hardware market. 

If the new family of AMD GPUs are anywhere near as world-rockin' as the Zen2 family CPUs have been, they might well soon be sucking wind with their biggest prosumer market: Content Creation.

mnem
"People are staying away in droves..."

[bd139]

Nah that’s not going to happen. It’ll be in all consumer shit boxes and business desktops with known hardware subset and everyone else will still use x86-64 until all the old hardware has died.

X86 died about 10 years ago. We’re still flogging the charred remains of the dead horse.

[mnementh]

I can't say I don't wish what you say is true... it's just that the current SotA in content creation still is high-BW x86/64. They'll have to pull a mighty big rabbit outta their arse to beat Zen2+R7/R8 with that.

mnem

[bd139]

Bus throughput is already there. Also ARM scales up in cores and latency much much better.

Read this: https://www.anandtech.com/show/15578/cloud-clash-amazon-graviton2-arm-against-intel-and-amd/3

[Specmaster]

FFS, people are losing their marbles on eBay, I just cannot believe the shit prices people are paying for what is potentially a POS    I was watching an AVO meter as a possible spare part donor for my resistors to fix mine with, it clearly has a major issue with it as can be seen by the photo, notice the pointer position, and yet they just paid £34 plus £10 P&P. The seller had listed it as "Untested".

[bd139]

Yeah it’s bloody amazing. I’ve made a fortune this month 

[bd139]

crap... could not fix it today.... but at least.. it being a part unit i got it to switch on.. ;-)

That was quite funny. Same issues with switches I had with mine and same contact cleaner used 

[tonyalbus]

crap... could not fix it today.... but at least.. it being a part unit i got it to switch on.. ;-)

That was quite funny. Same issues with switches I had with mine and same contact cleaner used 

Thats very interesting.... what in the end was your fix?

[mnementh]

Bus throughput is already there. Also ARM scales up in cores and latency much much better.

Read this: https://www.anandtech.com/show/15578/cloud-clash-amazon-graviton2-arm-against-intel-and-amd/3

I think you discount PCIE 4.0/Zen2 too much; people have been making a living doing this for almost a year now and they are soon going to be in for a rude awakening as ground-up PCIE4.0 expansion hardware designs actually hit the market. GPU/CPU distributed processing is a huge advantage in content creation/rendering, so the external bus is still as important or more so than the internal mesh/memory bus. Not saying Neoverse memory architecture isn't equivalent (on paper)... but so far that's it. EQUIVALENT, and then ONLY OCed like fuck to get the mesh up to ~2TB/s. Not earth-shakingly better. It will be interesting to see how dual 128-bit stacks up against native 256-bit tho.   

BUTT... and this is a big butt... I'm really not sure how much of this recent server-centric explosion in hardware is going to trickle down to even high-end user workstations; I expect there will be HUGE pressure to follow Intel's example WRT new tech and "keep it in the priesthood" for probably as long as we're both still on the right side of the grass & flogging bits.

mnem
 

[mnementh]

   FFS, people are losing their marbles on eBay, I just cannot believe the shit prices people are paying for what is potentially a POS    I was watching an AVO meter as a possible spare part donor for my resistors to fix mine with, it clearly has a major issue with it as can be seen by the photo, notice the pointer position, and yet they just paid £34 plus £10 P&P. The seller had listed it as "Untested".

Yup... and once they turn it upside-down and paint the knobs so you can "see the smiley-face", then hot-snot one of these "vintage LED" bulbs on top... that meter position becomes a feature, not a fault.

BAM!!! £250 on Etsy... 

mnem
 

[med6753]

Yeah it’s bloody amazing. I’ve made a fortune this month 

I actually sold something too. Amazing, isn't it?  I got $50 for a working spare DM44.

But it barely made a dent in the negative cash flow.   

[tonyalbus]

Yeah it’s bloody amazing. I’ve made a fortune this month 

I actually sold something too. Amazing, isn't it?  I got $50 for a working spare DM44.

But it barely made a dent in the negative cash flow.   

same here... i am not that brave to say that last sentence to 'the' wife....
if she thinks i am on zero... i am also good with that 

[bd139]

crap... could not fix it today.... but at least.. it being a part unit i got it to switch on.. ;-)

That was quite funny. Same issues with switches I had with mine and same contact cleaner used 

Thats very interesting.... what in the end was your fix?

One of the caps in the SMPS in it was iffy. Seemed to go away after it warmed up. Also wouldn’t measure anything. Switch cleaner sorted it.

[bd139]

Bus throughput is already there. Also ARM scales up in cores and latency much much better.

Read this: https://www.anandtech.com/show/15578/cloud-clash-amazon-graviton2-arm-against-intel-and-amd/3

I think you discount PCIE 4.0/Zen2 too much; people have been making a living doing this for almost a year now and they are soon going to be in for a rude awakening as ground-up PCIE4.0 expansion hardware designs actually hit the market. GPU/CPU distributed processing is a huge advantage in content creation/rendering, so the external bus is still as important or more so than the internal mesh/memory bus. Not saying Neoverse memory architecture isn't equivalent (on paper)... but so far that's it. EQUIVALENT, and then ONLY OCed like fuck to get the mesh up to ~2TB/s. Not earth-shakingly better. It will be interesting to see how dual 128-bit stacks up against native 256-bit tho.   

BUTT... and this is a big butt... I'm really not sure how much of this recent server-centric explosion in hardware is going to trickle down to even high-end user workstations; I expect there will be HUGE pressure to follow Intel's example WRT new tech and "keep it in the priesthood" for probably as long as we're both still on the right side of the grass & flogging bits.

mnem
 

Add per-watt to everything and that’s where the money is. PCIE4.0 is nice but it’s really edge case stuff that benefits. Less watts = higher density. NUC with an EPYC in it on your desktop is what we’re talking here. Or a 42U compute rack with 6x the compute in it for the same power.

One killer for me is lots of cores. I work on stuff that is highly parallel and x86-64 craps our fairly quickly on core scalability. And also NUMA is a mess on x86-64. Those problems are gone on ARM.