Test Equipment Anonymous (TEA) group therapy thread

[AVGresponding]

Or the way Europe is supposedly a continent, when all that separates it from Asia are the Urals, which are sandhills compared to the Himalayas, but they refer to  the part of the world where India, Pakistan, & Bangla Desh are as the "sub" continent.

People "reject your reality & substitute their own".

I believe that refers to continental plates rather than political divisions.

[mnementh]

All today's delivery victim pictures have reminded me about those Chinese number tubes that got sent in a grey bag (the kind of thing clothes are sent in) with no protection, finally time to do an evaluation of the tube with bent pins & autopsy of the smashed tube.
Well the surviving tube is useless for what I was hoping to use them for if they had been packed properly, a kind of force fit in the counter, plus the pin spacing is different. 
      An autopsy on the smashed tube to find out if they used the same piece for the 2 & 5 like some Russian number tubes, well turns out they don't.      

I won't be ordering any more even if they had been suitable for my TE, due to the fact they can't be arsed to pack them properly & are wasting a finite resource of NOS parts.

David

Uggh... that sucks. But a resourceful guy like you has to be able to find a use for those loverly numbers. 

mnem

[mnementh]

Fuck. I just noticed a scratch... a real, permanent, not-gonna-clean-it-away scratch aboot 20mm long... in my 32"/144Hz gaming monitor. Y'all just hadda jinx me, dinncha...?

mnem

Dwagons should keep their claws fully sheathed until they're actually required ! 

Well, at least the damage wasn't Chalupa-induced. Then there'd be nuthin' left but ash...

mnem
Hope all y'alls had a Happy Thanksgiving!

[mansaxel]

Thanks for the feedback, glad, that everything is okay.
Someone named them as "Bob-Widlar-Memorial-OpAmps".    

They are uA709AHM, the red dot comes from Rohde & Schwarz, they have selected them for some (to me) unknown paramters.


I have 200+ pieces of them, more than enough for a lifetime.
If you are interested in some of them, send me a PM. :-)

Presumably because they either are matched to a specific characteristic, or because they are outside of the requirements... do you know if ones used in their TE are dotted or not?

The Telefunken VF14 used in the Neumann U47 microphone was ruthlessly selected at Neumann for low microphonics and a number of other things, thus became a VF14M. This was a process that the entire production of VF14 went through. Those not fulfilling the required performance demands were shipped back to Telefunken, and used in a simple Allstromempfänger. Today, audiophools willingly buy NOS VF14 (i.e. Neumann rejects) valves  to put in their U47 microphones. Which is not a very clever thing to do, if you want to preserve the microphone as it should be.

At the end of the VF14 production era Neumann noticed that the acceptable portion of new batches started to shrink. They did some complaining, which was stone-walled, and then resorted to more cunning tactics; all rejects were marked with a small, somewhat hidden paint dot. It should not come as a surprise that they found the little dot on several valves in the next shipment. 

Thus ended the VF14M era.

[Robert763]

Device selection certainly happens. Many years ago I worked for a company that had an aircraft radio reapair workshop. We did  lot of King Silver Crown general aviation radios including the KX175 VHF NAV/COM and KR85 ADF.
One of the techs was repairing a KX175 and suspected a PLL chip a 4046. Checking stock he found we did not have the King part No. in stock.  But he had replaced a 4046 in KR85 recently and knew we had spares. On checking the King numbers were different in the two radios. To confirm the fault he fitted a "KR85" 4046. This cured the original fault but the PLL would not lock over the full frequency range dispite adjustment. We ordered replacements of both parts for the repair and stock. On inspection all the chips were identical 4046s  even having the same date code but had different coloured paint dots (white and red) corresponding to the King part number. Talking to King technical they were selected for various parameters including sensitivity and noise.
Also of interest these radios were certified to aviation operating temperatures but virtually all th IC's were plastic package and many the commercial 0 to 70 degree range rather than the -55 to +125 ones, mostly ceramic, that you find in airline or military radios.   

[AVGresponding]

Just goes to show why some equipment is so expensive.

The cost in man-hours to characterise these parts would have been a not insignificant fraction of the overall manufacturing cost.

[Saskia]

picked up a UniT Oscilloscope for 60 Pesos.

  you may think, but it's new in the box and should be flippable for twice the money.

[Specmaster]

Speaking of eBay and some stupid items / prices on it, how about this then.

https://www.ebay.co.uk/itm/NEW-Unused-VINTAGE-1965-AVOMETER-MODEL-8-MK3/254781947719

[factory]

And looking closely at the pictures I'm not convinced it's new either.

David

[bd139]

Yeah that’s not new. No way.

I am always suspicious of new looking old instruments. A lot of stuff looks like that because it broke early on and was never used or the original owner blew it up and it was never used.

[factory]

Yeah there was a new looking AVO at work in the leather case, unfortunately the meter movement was smashed, I suspect it got dropped and abandoned on a shelf for decades.

David

[Specmaster]

And looking closely at the pictures I'm not convinced it's new either.

David

Neither am I, the white lettering on the switches is coming out, the positive lead is falling apart on the boot and the back of the meter shows many scratches and given that back in the day it only cost £23 new, their valuation is pure fantasy, even if it was still a sealed boxed unit 

[Cerebus]

Or the way Europe is supposedly a continent, when all that separates it from Asia are the Urals, which are sandhills compared to the Himalayas, but they refer to  the part of the world where India, Pakistan, & Bangla Desh are as the "sub" continent.

People "reject your reality & substitute their own".

I believe that refers to continental plates rather than political divisions.

Indian and surrounding countries do indeed have their very own continental plate as does Arabia. Obviously names for things are geopolitical, but the Indian plate throws up features that tend to be natural borders which I guess is what makes for that particular set of plate boundaries happening to coincide roughly with political boundaries. Indian suffers from the Mercator Projection effect, and is bigger than it looks on the map against the more northerly places that make up the [self-]important parts of the world; when you take its full size into account sub-continent does seem appropriate.


(Click to embiggen.)

[Cerebus]

Just goes to show why some equipment is so expensive.

The cost in man-hours to characterise these parts would have been a not insignificant fraction of the overall manufacturing cost.

Snatched from another topic, a post I made recently about the testing of LMC6001s, which is the major part of what makes them an expensive part:

The LMC662 operational amplifier has a maximum input bias current of 2 pA, and a typical input bias current of 2 fA (a thousand times smaller) and costs £1.35 for one off. The LMC6001 has an individually tested guaranteed input bias current of 25 fA and costs £13.40 for one off.

The two different parts are almost identical internally, the significant difference is that the LMC6001 spends enough time on a test rig to guarantee that low input bias current and that extra testing time is what makes one part cost ten times what the other does. The bias currents are almost entirely made up from the gate leakage currents in the input MOSFETs in these OPAs plus the leakage currents in their protection diodes.

One ampere is \$6.2415090744 \times 10^{18}\$ electrons a second, so 1 fA is \$6,241\$ electrons a second, so it should be obvious that fA current measurement is, shall we say, challenging.  In this video you can watch Bob Pease and Paul Groehe (spelling?) discuss the design of the initial laboratory test rig used for qualifying the LMC6001 at National Semiconductor. In particular you can see the lengths they had to go to to shield the DUT from external electric fields to make measurements at this current level possible.


(The discussion of femtoampere current measurement starts at 13 minutes in.)

[AVGresponding]

And looking closely at the pictures I'm not convinced it's new either.

David

Neither am I, the white lettering on the switches is coming out, the positive lead is falling apart on the boot and the back of the meter shows many scratches and given that back in the day it only cost £23 new, their valuation is pure fantasy, even if it was still a sealed boxed unit 

Not just a fantasy valuation, have you read the description?

"It's believe that it was originally located at the CERN facilities in Switzerland that are used for atomic particle the research."

Yeah, two things there, learn how to construct a sentence that makes grammatical sense, and show me the fucking asset label!

Get the FUCK out of here you used-car-salesman lying sack of shit scamming parasite!!!!!!
 

[xrunner]

"It's believe that it was originally located at the CERN facilities in Switzerland ..."

He did say "believe" 

[bd139]

A right Swiss Tony 

[AVGresponding]

Sorry, I got a bit triggered there, but this is the type of scumbag that scams the pension pots away from little old ladies.

[Specmaster]

Sorry, I got a bit triggered there, but this is the type of scumbag that scams the pension pots away from little old ladies.

Yeah, I don't Ffffing care if it was used on the Apollo moonshot, at the end of the day, its just a nice example of an old out of date meter of which there are loads of other examples around, they are not yet rocking horse sh1t, so that seller can shove it where the sun don't shine 

[bd139]

Reminds me of my father in law to be honest. He was the sort of person who'd sell you a Mondeo with three wheels and one working window using the same technique.

[med6753]

7603N PSU re-cap, round 2. New set of tools ready to do battle.



And progress so far. I feel like a 19th Century battlefield surgeon performing amputations with no anesthesia or pain killers. Going much slower than anticipated but they finally are coming out. With enough added expletives that I should probably wash my mouth out with soap.  But good news is no board damage.   



I think I've aggravated myself enough for today. Will continue the battle tomorrow. 

[mnementh]

mnem

[mnementh]

Sorry, I got a bit triggered there, but this is the type of scumbag that scams the pension pots away from little old ladies.

Yeah, I don't Ffffing care if it was used on the Apollo moonshot, at the end of the day, its just a nice example of an old out of date meter of which there are loads of other examples around, they are not yet rocking horse sh1t, so that seller can shove it where the sun don't shine 

My ex-NASA 2465 sez "Bite my shiny metal and plastic ass."   I concur.   

mnem

[Saskia]

picked up a UniT Oscilloscope for 60 Pesos.

  you may think, but it's new in the box and should be flippable for twice the money.

And flipped.

[Specmaster]

Well that was flipping quick (pun intended)