Test Equipment Anonymous (TEA) group therapy thread

[Vince]

OK OK.... newer is better indeed.

I mean EPROM is better for hacking stuff but I don't intend to do that.
The reinforced 4 peg BNCs are much more desirable to me !

Mounting the BNC on the PCB rather than screwed to the chassis, is a crime in itself, but using only two pegs to secure them on top of that is.... just plain.... "Please fire me I hate my job, and take me to court as well !" territory...

I understand why I keep hearing about BNC getting loose on these scopes.... glad to hear they reinforced them in later models..

[wkb]

Tanned I would say? (the UVEPROMs mercilessly left endlessly under that UV-C tube I mean)

[Vince]

Was shuffling some stuff around and that led me to digging out my Tek 11401 scope.

As a refresher, I got it just a year ago now. It was working just fine as far as I can remember, except it would either not power up, or it would freeze at random places during the boot process, and I had to power cycle it like 10 or 12 times not even kidding, to get it to fully boot. However once it managed to do that, it was working just fine.

So I thought the PSU needed recapping probably.

So I was curious and tried to power it up, thinking most likely the PSU by now has completely failed and it would not even attempt to boot.
But hey, if you don't try you don't know, so I tried...

Well it has not worsened... after a year of sitting, it's not better or worse than it was a year ago.
After 15 minutes of repeated boot failures, it eventually did boot, operate normally for.... one minute before it froze.
Power cycled it.... working properly now... been working for 45 minutes and still not frozen, winner.

So that's great. I will recap the PSU when I get time, which is to say not very soon... this scope is so complex inside that just looking at it from 10 meters away is enough to scare me. My TDS 544A in comparison, feels like a 5 Euro Hameg scope from the '70s.

Or maybe it's some backup battery for some NVRAM in there, that's dead and causing the CPU some trouble. Who knows. Will look for that as well.
Well maybe not... I just realised that somehow after a year sitting, the date and time in the scope are still good...amazing for a scope 35 years old or something...

I just downloaded the many manuals available on Tekwiki, hopefully there are enough information in there to help me fix it.
The scope has both GPIB and RS-232 at the back, will be cool to play with that, and potentially get troubleshooting info / help.
This thing is so complicated despite its old age, maybe there is such a luxury as being able to read the level of all the voltage rails via the com ports...

There is also a printer / Centronics port at the back, would love to make some hard copies, but according to the utility menu the scope only handles 8 or 24 pin dot matrix printers, no laser no ink jet. Too old a scope I guess. Tekwiki says it was produced between 1986 ans 1989, which might explain this...
I will see if there is maybe a firmware upgrade that would give me more printer options... failing that, maybe someone out there devised some gizmo I could plug to the centronics port to convert the dot matrix stream into something an inkjet could print... or maybe some old inkjet printers have the ability to take dot matrix data natively, who knows.

How many of you have a 11K series scope ?!  I can't remember seeing anybody posting about it since I joined TEA 3 years or so ago ?

Terra, the old Tek specialist (old Tek not old specialist...), have you got one ? Ever worked on / fixed one ??

Anyway, 23h30, time to go to bed.   

[wkb]

Not worked on, worked with. We had one at Philips Information Systems in the early 1990's. Not your daily driver this thing. But very advanced for its time. Only thing lacking is a self propelled tracked carrier to move it around 

[wkb]

as for printing from it: maybe this might do it?

https://github.com/boriz/CentronicsArduino

[TERRA Operative]

I have seen them around the internet, but never seen one in person...
I don't think I have seen one on Yahoo Auctions either, well, not at any reasonable price at least..

I bet they cost a big number when new too.

[BU508A]

I bought a LED, 0.1W 250-260um UV-C type with 20mm copper base.

Where did you buy that LED?

[AVGresponding]

I bought a LED, 0.1W 250-260um UV-C type with 20mm copper base.

Where did you buy that LED?

I got one from Mouser a few months back, Vishay part number: VLM35CB20-275-120

[TERRA Operative]

That datasheet needs a bit of proof reading...

To prevent inadequate exposure, wear protective eyewear.

lol.

[Vince]

Tek 11401.

[..] Only thing lacking is a self propelled tracked carrier to move it around 

What are you talking about ? I can lift it with just one pinky easily ! 
OK.... I confess, I had to use a pulley crane to lift it onto the bench 

It's just as big and heavy, maybe a bit heavier, than my ancient 500 series hollow-state Tek scope boat anchors.

This 11401 is a modern boat anchor... but still a very efficient boat anchor... rated for cargo ships up to 500 meters long.... 

as for printing from it: maybe this might do it?
https://github.com/boriz/CentronicsArduino

Thanks. A bit cumbersome and requires that an appropriate viewer exists at all, but it is useful and I didn't even know such thing existed, so good to know...

I have seen them around the internet, but never seen one in person...

Next time you take a cheap flight to visit Frogland, you are welcome to stop by to play with it .... and bring all my scopes with you while you're at it ! 

[BU508A]

I bought a LED, 0.1W 250-260um UV-C type with 20mm copper base.

Where did you buy that LED?

I got one from Mouser a few months back, Vishay part number: VLM35CB20-275-120

Thanks.
But this particular LED has an emitting wavelength of 285nm. I've asked, because I'm interested in the 250 - 260nm emitting wavelength range.

Thorlabs has some of them but they are a bit expensive.

[Vince]

I need some education please.... what is the purpose, the interest, in concrete terms, of offering 2 dozen different wavelength in the UV range ?

Are there specific uses cases / products that all require their very own wavelength... or else they just won't work at all ?!

I am also intrigued as to why UV LEDs are cheap / affordable, at 10+ bucks a pop, down to 375nm, but then suddenly, sharply, all wavelengths shorter than that, are litterally 20 to 40 times the price ?! 

Do EPROM manufacturer, well, did they back in those days, specify what UV wavelength gave the best / quickest erasing performance ?  Did they show plots/graphs of erasing times versus wavelength ?

[PA0PBZ]

How many of you have a 11K series scope ?!  I can't remember seeing anybody posting about it since I joined TEA 3 years or so ago ?

Not a 11K, but I have a DSA601 which looks surprisingly familiar. I guess it's kind of a successor to your model, introduced in 1990. Still working fine but the size and weight makes it a bit impractical to use or even to sell...

[Vince]

Ah yes ! The DSA601 does qualify ! 

Just had a quick read on Tekwiki.

The DSA600 series looked indeed like the successor to the 11K series.

11K was the original design, spannign the late '80's, then then the revisited it with the DSA600 series, spanning the early '90s.

The DS600 series appear to be basically the same mainframe, just with a slightly higher profile which let them accommodate an optional floppy drive.
They also slightly relocated the controls that are around the screen.

Electrically the main difference seems to be that it's less of pure sampling scope that the 11K was (high B/W but very low sampling rate, 20MS/s, but very high resolution, 10 bits natively, more in high res mode). The DSA600 have fro 500MS/s up to 2GS/s, but a lower vertical resolution, 8 bit natively, 14 bit in hi-res, but tehy do say that the effective number of bit is only 4.5 at 1GHz...

You can't have it all as usual.

So I guess that made it a more "general purpose" scope than the 11K was. I guess the 11K was too specialized, they didn't sell enough to make a sizeable profit, so compromised the design to make it a bit more general purpose, hence appeal to a wider audience, sell more of them and make some profit to justify the tremendous R&D cost that these scopes must have engendered...

[m k]

I bought a LED, 0.1W 250-260um UV-C type with 20mm copper base.

Where did you buy that LED?

From "uvc 250nm" ebay.
Some are also offering raw LEDs.
It's "their" product so maybe it's safe.

For earlier mini regulator module,
since zener is not really protecting I guess single transistor regulator is a better way.

[m k]

I need some education please.... what is the purpose, the interest, in concrete terms, of offering 2 dozen different wavelength in the UV range ?

EPROM is insulated floating gate thing, the usage is ionizing the insulation.
So program voltage is avalanching the insulation oxide and UV light is ionizing it sort of one by one.

I guess higher energy is higher energy so anything shorter wave light would do, if insulation oxide behaves.
Seems that I have a recollection that those late last millennia exposed chips were toasted.

E,
nail polish seems to more complicated, including polymers and photoinitiators.

[TERRA Operative]

Do EPROM manufacturer, well, did they back in those days, specify what UV wavelength gave the best / quickest erasing performance ?  Did they show plots/graphs of erasing times versus wavelength ?

According to Wikipedia, the optimum light frequency is 253.7nm
https://en.wikipedia.org/wiki/EPROM#Details

I have seen calculations in datasheets for erasure time vs light intensity, but usually 30-45 minutes under a single UV tube eraser gets the EPROM's good and reliably blank without damaging them. It would take days to cause damage though.

[BU508A]

I need some education please.... what is the purpose, the interest, in concrete terms, of offering 2 dozen different wavelength in the UV range ?

Are there specific uses cases / products that all require their very own wavelength... or else they just won't work at all ?!

A few years ago I've built an UV lamp with UV LEDs of various wavelengths.
It looks like this:


Fluorescent substances absorb UV light of different wavelengths. The idea behind this lamp is to find out which substance fluoresces best at which wavelength.
My lamp starts at 395nm in 10nm steps down to 355nm (two LEDs per wavelength). I find it interesting to use it to illuminate various things (ID cards, banknotes, etc.) and see what lights up when. It's a primitive optical spectrum analyser if you like.
I'd like to extend the available wavelengths but as you've found out, UV LEDs becomes more and more expensive the shorter the wavelength is.

I am also intrigued as to why UV LEDs are cheap / affordable, at 10+ bucks a pop, down to 375nm, but then suddenly, sharply, all wavelengths shorter than that, are litterally 20 to 40 times the price ?! 

I don't know the exact reason but I think the yield rate decreases significantly with the decreasing wavelength.

Do EPROM manufacturer, well, did they back in those days, specify what UV wavelength gave the best / quickest erasing performance ?  Did they show plots/graphs of erasing times versus wavelength ?

To my knowledge, they always recommended for erasing EPROMs using an UV-C lamp with a wavelength peak around 250nm. Mercury has an emission line at about 253nm.

Edit:
A (not so good) example, where I'm testing some fluorescent dices:

[Vince]

Thanks Chaps, was very interesting !  My curiosity has been satisfied 

Cool project BU !

[factory]

Do EPROM manufacturer, well, did they back in those days, specify what UV wavelength gave the best / quickest erasing performance ?  Did they show plots/graphs of erasing times versus wavelength ?

According to Wikipedia, the optimum light frequency is 253.7nm
https://en.wikipedia.org/wiki/EPROM#Details

I have seen calculations in datasheets for erasure time vs light intensity, but usually 30-45 minutes under a single UV tube eraser gets the EPROM's good and reliably blank without damaging them. It would take days to cause damage though.

And if you want to damage them, 3 seconds in a microwave will do it  , see post #7 here. https://www.vintage-radio.net/forum/showthread.php?t=138920
I still don't know if the OTP version (no-window) being wiped in a microwave, is a myth or not. 

David

[m k]

I'm sure there is a band of radiation and power of it that can blank the OTP ROM, if its style is insulated floating gate.
But what else simultaneous things that radiation does is another thing.

Since plastic case would be penetrated it's also so elsewhere around the chip.
Maybe address latch is also blanked.

This penetrability is an interesting thing, business as usual for folks around RF and above.
Nowadays it's easy to understand that X-rays go through and selective windows are, well selective.
But some materials are much more exotic, like things that are transparent when wave length is correct.

Very high pressure can also change things a lot, but that's a different thing.
Different thing is also that frogs can float if magnetic field is strong enough, frogs were not harmed.

[Robert763]

I wonder if the ban on fluorescent lamps coming in next year wil affect the supply and cost of UV-C tubes much.
Zenon Flash yubes with quartz glass will work too. Much quicker. Dataman used to sell one.
http://www.grifo.com/PROG/uk_Eraser.htm

[factory]

No idea, the UV-C tubes are used for more than just EPROM blanking, they must be vastly outnumbered by all the germicidal uses. I seem to remember water sterilisation units being serviced at work in the distant past, I'm sure they had a 2 foot UV-C tube, have LED versions become cheap enough for these applications yet?

David

[TERRA Operative]

I used to work in water treatment, we usually used 4 or 5 foot long tubes in banks. They'll hive you a nice sunburn without too much trouble.

I played with Wedeco brand systems. They are French I think? I can't get away from these Frenchies!  It's ok though, all the French people I've met so far are always pretty cool.

PDF warning... This is actually who I used to work for:
https://pncwa.memberclicks.net/assets/2010ConfTechPresentations/Session12/2010%20pncwa-%20session%2012-2%20-%20disinfection%20-%20matthias%20boeker.pdf

[AVGresponding]

I wonder if the ban on fluorescent lamps coming in next year wil affect the supply and cost of UV-C tubes much.
Zenon Flash yubes with quartz glass will work too. Much quicker. Dataman used to sell one.
http://www.grifo.com/PROG/uk_Eraser.htm

No, specialised tubes will still be produced, but you can bet the price will skyrocket