Test Equipment Anonymous (TEA) group therapy thread

[PA0PBZ]

Anyone recognise this German made power connector (made by Hirschmann) and know what the part number of the cable mounted connector is?

I think that's a STAK2.

[Ice-Tea]

Dusting of a Tek 2445A.

Previous owner had fun...

[McBryce]

Anyone recognise this German made power connector (made by Hirschmann) and know what the part number of the cable mounted connector is?
It's been fitted to a Meratronik V543 multimeter at some point in the past 35 years, this is not urgent as the DMM is supposed to be faulty (does not respond to any input) and I've got other more urgent things in the repair queue.

David

https://www.distrelec.ch/de/kupplungsdose-2p-hirschmann-stak-20/p/14386540

https://www.distrelec.ch/de/geraetestecker-2p-hirschmann-stasei-200/p/14386538

McBryce.

[factory]

Thanks to both of you, both are compatible, STAK-2 has no cable strain relief and STAK-20 is a bit longer but has cable strain relief, size has been double checked and I'll add one of those to the next Mouser/RS/Farnell order.

David

[factory]

Dusting of a Tek 2445A.

Previous owner had fun...

 
I noted some custom labelling of the recall setups on one off mine (also a 2445A, ex-mil), no idea how they were changed, but the fact they were still there after a battery change, was a good sign the cal data also survived. 

David

[Vince]

Wow thanks for the good laugh you two !  No such fun in my 246X scopes for sure.

Talking about old Tek scopes, look what I just got today ! 

Remember recently that TDS 340A I got for 60 Euros with most likely just a dead NVRAM battery, with FDD and full suite of I/O at the back ?

Well, as soon as I bought it, the seller said :"Oh BTW, I have another one with the same fault if you are interested ? I think it's a 360 ".

Eh ?! 360 is twice the specs of the 340A : 200MHz / 1GS/s versus 100MHz / 500MS/s , of course I want it !
I asked for pics of the thing and of the error log to make sure it was indeed the same fault.
That 360 is just like the 340A : in good nick, with FDD and printer port, serial, GPIB and VGA at the back.

However the error log is less promising than the 340A (so the seller lowered the price, 55 Euros instead of 60) : 3 pages worth of bad news. All 3 pages somehow show the same contents, so I attached only the first page.
90% of it are Calibration errors but sadly none of them mention the NVRAM explicitly, so might be another, much more difficult problem to diagnose/fix and I might not be smart enough to figure it out. I am trying to remain optimistic though : maybe it is indeed all related to the NVRAM, but this scope being a vanilla 360, unlike the 340 which is a revised / 'A' version.... maybe Tek modified the error messages in the 340A, mentioning the NVRAM to make them extra clear.
That's the optimistic me. The pessimistic me however notices that the scope still displays proper date and time ! Which means the battery in the NVRAM/RTC combo, must still be good 
But the optimistic me might come back and make the hypothesis that the RTC and RAM might have different requirements for standby voltage. The RAM might lose its contents before the RTC does. So overall I think I will start by replacing the NVRAM anyway, and go from there...

Then the Acquisition side of things also fails, as you can see. There is only one message about it, but that's one too many to me.

So the idea is to practice on my TDS 310 parts scope : first to cut open the NVRAM package to expose the battery and try to replace it. See if that works. Then try removing the NVRAM and replacing it. If that's successful and I feel confident enough, I would then do it on the 360. Then if I can fix that 360, I would replace the NVRAM on the 340A and sell it. Paid only 60 Euros for it, but if I can get it to work with a blank error log, I might get 150 to 200 Euros for it.
Then I would keep the 310 donour in case I need other bits off of it in the future.

[TobyG]

Anyone recognise this German made power connector (made by Hirschmann) and know what the part number of the cable mounted connector is?

Hirschmann Stasei 2 is the socket, from the ST series, as per the attached *pdf.
"mit Zugentlastung" = with strain relief

[Peter_O]

Not sure if this is going to catch a shitstorm. 

But with such a question you can ask a LLM. 

I mean, just in case the community is not available.

 

[TERRA Operative]

@Vince, they might be good candidates for FRAM swaps... I got some spare PCB's I can send for cheap postage in a standard envelope if you want?

[factory]

Not sure if this is going to catch a shitstorm. 

But with such a question you can ask a LLM. 

I mean, just in case the community is not available.

 

Well it failed with the part number of the chassis mount connector and didn't really give part number I actually want to order with strain relief, a mistake I don't want to make given these aren't cheap connectors.
The kind of modern single part datasheet from Mouser/RS etc are OK, but the catalog pages with all the info & options added by TobyG is far better. Something I've noticed more & more these days, companies don't make it easy to find a catalog page(s) with the complete range of parts.

It wasn't an urgent request, as I mentioned in the original post about this part, it will be added to a future order, once I've got enough parts to order & qualify for the free shipping. I've spent a lot this week (£870 on auto-shite related annual test & necessary repairs), so this will be next month at the earliest.

The last point about community being not available, if this was the case then internet access and being able to buy parts online would also be not available, this would be a very bad outcome. And I would have had to resort to removing the connector, making a blank from scrap sheet metal, reinstating the plastic strain relief type cable bushing & fixed cable, that it would have left the Meratronik factory with in 1990.

David

[Vince]

@Vince, they might be good candidates for FRAM swaps... I got some spare PCB's I can send for cheap postage in a standard envelope if you want?

How cheap is cheap ?!    Japan is a long way from Frog land...

I have zero experience with these FRAM conversion kits... I have not looked into the TDS300 scopes yet to figure out what the specs / requirements are, so no idea if your boards will be an appropriate replacement ?

Give me a bit of time, I will try to have a quick look into that in the coming days, see the reference/specs of the NVRAM in these scopes, and price and availably of the FRAM.

I am still a bit warry of using FRAM, in the long term. I guess they must have a limited number of write cycles. Not much of an issue for calibration stuff as I guess the scope only writes these when you calibrate the scope, and each time you run the SPC procedure, so only once in a blue moon. however if the RTC is indeed built into the NVRAM, then it would write all the time into that FRAM chip, which might kill it quickly I guess. No ?

Plus, if the RTC is included in the NVRAM module, how will an FRAM replace the RTC in the first place ?! 

See ? I need to look into that more closely... will get back to you once I know more

[TERRA Operative]

If it has RTC, then you'll need a battery backed SRAM instead, which I am currently working on.

For non RTC NVRAM, the read/write cycles of FRAM will essentially outlast the rest of the scope.


Cheap is a few dollars, less than 10 for postage, PCB's free, but you'll need to source FRAM chips.

Keep us updated and we can work it all out.

[Vince]

OK, just spent a few minutes on the subject.... looked at pics of the main board on Tekwiki, no batteries in sight, so it must be located inside the NVRAM, which means the RTC chip most likely is in there as well, rather than soldered somewhere on the main board.  Pic suggest it's a Dallas DS1644-120, which is confirmed by the service manual and the schematics.

I puiled the datasheet. It's a 32KB RAM with indeed a built-in RTC. From the outside world / CPU, the pinout is 100% the same as a normal RAM so that's good. The RTC is controlled by 8 registers which are mapped to the 8 upper-most bytes of the RAM chip.

Looks like these are available new on Ebay, for less than 10 dollars !
However how "new" they really are.. who knows.... maybe it's new as in NOS that's 30 years old with a dead or soon to die battery inside, so not much help really.

I don't know if they are available in Europe though, with the battery issue problem blah-blah-blah... 
If I can find one locally for that cheap, it's worth a shot I guess. I would solder it onto a chip socket, this way if it turns out to be crappy, I can easily replace it later with your solution if you come up with one. Keep us posted...

I guess I could also try the simple route : crack it open and replace the battery only. I am sure people must have tried that on the interweb, will see how doable / realistic an option that actually is in practice...

So I guess the hard part for you would be to try to find an RTC chip available today, that works the same way as the Dallas one ? Because I assume there is no standard as far as RTC operation/control goes ? They all have a different set of registers used in different ways ?! 
At least, the Dallas datasheet tells you all about how their RTC chip works, so you are hardly working blind.
I guess worse case scenario, if you can't find any modern RTC chp that works 100% the same way as the old Dallas one, you could put a tiny 8 bit micro as an interface layer to translate the RTC commands coming from the Tek CPU, into commands that your replacement RTC chip expects ?

EDIT : now that we know the RTC registers are held in the same RAM as the NVRAM... we can sadly say for sure that if the date and time are still correct, which they are, then logically all the cal constants should still be there too ! So, sadly it looks like my calibration errors are not due to the NVRAM to begin with ?!
So... therefore it's more complicated and I stand no chance of fixing it ! 

Will try to replace that NVRAM anyway, just for "fun", as a learning exercise... will surely come handy to fix other TE I have or may buy in the future...

Well stupid me, yes it's still a useful exercise, as I need for sure to replace the NVRAM in the TDS 340A, then I can calibrate it and resell it...

[m k]

Back in the day RTC time started lagging first.

But shouldn't there be a checksum for memory content?
Maybe it's an old style passive component problem.

[TERRA Operative]

The NVRAM's on ebay et are all relabels or old/used items. The Dallas NVRAMS that have RTD functions haven't been made for so long that even a last production part will be too old now.

But, cutting the top off and replacing the battery is viable with some care (and ideally a mill of some sort), or you can buy a new reproduction if you don't want to make one yourself.
Or just wait a bit for mine to be tested.

[TERRA Operative]

Hey anyone here built or bought one of those TDS500/600/700 console debug adapters to use the serial port option to check diagnostic messages?

Like this one? https://www.ebay.com/itm/326440399800

I just need the pinout so I can double check my design of a USB adapter version...

[Vince]

The NVRAM's on ebay et are all relabels or old/used items. The Dallas NVRAMS that have RTD functions haven't been made for so long that even a last production part will be too old now.

But, cutting the top off and replacing the battery is viable with some care (and ideally a mill of some sort), or you can buy a new reproduction if you don't want to make one yourself.
Or just wait a bit for mine to be tested.

Thanks for the links Terra, duly bookmarked now 

The guy on Ebay claims his modules are EXACT functional replacements, yet everything in his ad suggests they don't have an RTC ?!
I guess it does not matter since he is in the USA so I would'nt be able to import it anyway. Plus it would cost me twice what I paid for the scope so... not a good deal at all.

That said, I noticed that my TDS 310 does NOT have an RTC in its NVRAM ! So it's not mandatory for these scopes to run then...
Then I found this page where a guy with a TDS 380, replaced the NVRAM with an FRAM like you suggested to me initially, with NO RTC, yet his scope works just fine he says ! Passes POST, all diagnostics, SPC etc, no visible ill effects. So that's good.

https://www.barbouri.com/2024/06/17/tektronix-tds-380-nvram-replacement/

 So I guess the RTC is only used to display the date and time on the screen ?! 
However, teh datasheet for the DS1644 says that although you can retrieve the time just by reading the registers, it is not very reliable, you could get corrupted data in case the RTC happens to upfate those registers at the same time you are reading them. So, instead they strongly adise to firsst WRITE a bit in the registers, to stop the RTC from updating the "user" registers, so that no corruption can occur. Then once you have read the time, you WRITE Again that bit to re-enable the register updating.
The time on the screen is updated every second. So that means you have to write the FRAM twice every second 7200 times per hour... what's the endurance of an FRAM ? How many hours of using the scope, would the FRAM survive ? I don't know.
Still, at the least it means we can safely use an SRAM + battery solution instead of an FRAM, like this guy on Ebay sells.

Thanks for the other link on EEVBlog. This time the guy did a proper replacement, SRAM, battery, RTC chip, excellent. Even gives away the Gerber files, how nice of him.

As far as fixing my TDS 340A, the goal is to flip it t make profit, so I must fix the NVRAM issue as cheaply as possible. So no module I guess. I will try to replace the battery and call it a day.
Will try to find tutorials or YT videos on the subject to guide me...

But first I need to practice on my TDS 310 donour to see if I can remove/ desolder the NVRAM without damage. To help without I must first purchase a desoldering gun I guess... I assume wick won't be good or safe enough.
A milling machine ? No such thing but I guess if I buy a Dremel kind of tool and mount it on a stand, drill-press like, like when we used to drill our own PCB's 30 years ago, it might good enough.

Then I also need to get my cheap chinese programmer going, so I can save the original NVRAM just in case, and read/write the replacement should there be a need.
... but the programmers(s USB driver fails to install on my Windows XP virtual machine on Linux, so I am stuck 

I also need what gear and S/W is required to clear the error log in these TDS300 scopes, though to be faire I don't understand how there can be any log present if there is no battery left to keep it there once the scope is power off...

And of course I need an appropriate RF gen to calibrate these scopes !

So yeah, lots to do before I can fix my scopes !
So no hurry, you have all the time in the world to polish your prototypes Terra ! 

Give us a shout on TEA once they are available, to tell us all about them... maybe a video on your YT channel...

[TERRA Operative]

The link I gave to the ebay auction are exact functional replacements, I used them so far in my TDS784D and TDS794D and they work perfectly.
I actually just ordered another set from him just now to get my second TDS784D back up and running ASAP too.

The RTC works in my scopes with no problems (I just booted my TDS784D which has been turned off and unplugged for a few months and the time and date is still correct). He uses the original Dallas controller chip in his reproduction NVRAM's. It seems that somehow he got his hands on a stash of those now obsolete chips...

I also got the answer to my debug port question too.
https://qcte.ca/testeq/tek_tds/#internal-debug-connector

[Vince]

Oh, that's good to know. That sounds more interesting now, if not for the price and import issue.

How did you manage to import them to Japan ? Don't they put restrictions on importing batteries like we have in Europe ?

[TERRA Operative]

They just arrive... I guess if they aren't declared as batteries they don't get looked at too closely. They are only small coin cells anyway.

[dazz1]

The NVRAM's on ebay et are all relabels or old/used items. The Dallas NVRAMS that have RTD functions haven't been made for so long that even a last production part will be too old now.

But, cutting the top off and replacing the battery is viable with some care (and ideally a mill of some sort), or you can buy a new reproduction if you don't want to make one yourself.
Or just wait a bit for mine to be tested.

I found a modern version of the Dallas when I repaired my Wavetek 2520 here:   https://www.eevblog.com/forum/repair/wavetek-2025a-0-2-2-200mghz-rf-sig-gen-repair/

[tonyalbus]

Hey anyone here built or bought one of those TDS500/600/700 console debug adapters to use the serial port option to check diagnostic messages?

Like this one? https://www.ebay.com/itm/326440399800

I just need the pinout so I can double check my design of a USB adapter version...

i have one Jarred, DM me

[TERRA Operative]

I actually have got the pinout from fenugrec, who was able to find info they saved a while back from the now deleted Tek forums.
I have some boards ordered of my own design, so I'll be able to start playing with the debug port (and help to finish the design of my USB version) soon.

https://qcte.ca/testeq/tek_tds/#internal-debug-connector

[Early tube era]

I noticed, on this web site, only one series of old (2016, I think it was) posts about VOMs and VTVMs by Phaostron, Pasidena,  California, made in early 1950s.  Obviously such meters are now "collector's pieces," more or less.   They made a model 555 (vom), and a 666 (VTVM) and finally a 777 (VTVM).  One contributor, Enigma-man,  said he had a manual for the 777, and would be willing to email a copy to anyone needing it.which I now need, but Enigma-man has been inactive for years on this site.   I NEED A COPY OF THE MANUAL FOR A 777; can anyone help?  Thanks, all.

[Robert763]

Unexpected TEA.
A friend dropped by last night and left some TE in exchange for a spare part.
The TE is a RF power meter. Not one of the usual HPAK or Boonton, a Krytar 9000B. This is a digital meter with diode based heads. 1990s vintage. The head covers -30 to +20 dBm (-39 with reduced accuracy) from 100kHz to 12.5 GHz.
Krytar's main business is microwave components including diode detectors. Looks like the power meter was a market divergence. Krytar still exist but no longer sell meters. No manual but a "Contact us" message to them last night and ther was a PDF manual in my inbox this morning 
Meter all works and even the battery holds a bit of charge. makes a nice addition to my existing meters which are mostly thermal. The part I swapped it for owed me very little.

Robert. (Attachment Link)

Have had a chance to play with and use this meter and its very nice. The 100mW (20dBm) range is handy but I've just bought a useful addition. A Marconi-Sanders 20dB attenuator. It's a licence built Weinschel WA8. What is nice and unusual is it is rated at 10W So I get 1uW to 10W (-30 to +40dBm) with one head and one attenuator.