Test Equipment Anonymous (TEA) group therapy thread

[factory]

...snip...

Today I finally got round to working on the defective A23 count register board, now I had some replacement 74LS160 ICs for the HP 1820-0986 aka 86L75 (U2 to U7), using the logic comparator I found that all of them gave some, or many incorrect output states.



I ended up replacing all six of them and afterwards all was well & no more 7/9s showing at the same time. I also put the old ICs in the comparator and confirmed five of the six were very borked. 



The casualties from these two boards, clearly Nat Semi suck. 


David

That swath of destruction smells more like PSU regulation fail or lightning damage than rando component fail... is it possible you bought a "donor" unit that was assembled at least in part out of faulty boards from other units?

mnem
 

It was bought at auction last year so no history, there was another in the same sale, wonder if that one worked?

The regulator boards were all fine, despite the shorted main smoothing can capacitors & rectifiers and all the original parts went back into the +175V regulator board, after I eventually found the transformer winding was defective.

Most of the boards have components with 1976 to 1978 date codes, most of the high frequency front end has been replaced with the later ones at some point in it's life, apart from that & minor repairs, I can't tell if it got used as a donor for another. I put the Xs on the corners of those faulty boards, to avoid mixing them up with the good boards from the other 5340A.

Others have had the A23 board fail in the same way, requiring some replacement 1820-0986 aka 86L75 (74LS160) ICs, I suspect the Nat Semi 86L75 age badly, this board had been heavily reworked in the past too, they didn't bother cleaning the flux residue on the top row of ICs.


Others faults have been the timebase selector (multiplexer IC) which had a minor failure and the TI 74188 BiPROM on the control board which has brain rot, still waiting on the Soviet clones. And still need to investigate the high frequency section.

David

[Neomys Sapiens]

I can send you a bare OCXO PSU PCB, a replica I made of the original one if you like.

If only someone would finally say that about my 5334A!

[Cerebus]

So even if just using Cu-Cu unions, the sensitivity to thermal effects at this low of a level is extremely high. However, according to Keithley manual, Cu-Cu union has a Seebeck coefficient of 0.2uV/Cº. So the measured voltage without the zero enabled is still way too high, because it would imply a 75 Cº temperature difference!

One of the drawbacks of working with naked copper is that the Seebeck Coefficient of copper to copper is one one the lowest, but copper to copper oxide is one of the highest, in excess of 1mV/ºC. So if your copper to copper connection has any tarnish on it you're worse off than of you're using 'inferior' materials. People who do this seriously treat cleaning materials and de-oxit as essentials as much as their beloved low thermal EMF interconnects.

[Neomys Sapiens]

It is an often repeated stereotype that the Italians build 'em pretty...well, not always.
As there was a rather lengthy list of VTVMs, I think this one was missing. And it could be a looker if they had cared to use different knobs.
On offer on Ebay.de: https://www.ebay.de/itm/325005201290 (NAWTS)

[Vince]

Varta battery :

OK so it's done charging for the second time.

Started at 18H00 yesterday, C/10 around 11mA.

Within a few minutes voltage rose up to spot on 10 V and stayed there up until 4AM when I went to bed, i.e for 10 hours total.
When I woke up 8+ hours later at 12H45, voltage had gone up a bit, at 11.5V.

So in total it charged for 18H45min at C/10.  A bit more than theoretical time, but not much, plus the whole point as I understand it, of charging at C/10, is that it's low enough that you can leave it unattended, it's not gonna blow it.

Anyway, Wilson did a good job and charging current remained close to the set 11mA throughout. It was varying constantly up and down very slowly, but always within reasonable limits : about +/-   0.25mA, happy enough with that.

So when I disconnected it at 12H45, voltage went straight from 11.5V down to 10V where it had been most of its time anyway.
Now 22H45, so after 10 hours disconnected, voltage decreases extremely slowly. Now down from 10.0V to 9.6V.

So looks like 9.6V it will be then.

So, could it be this battery has not 7 but 8  cells ? Like....8x1.2 = 9.6V !!! 

The label on the battery is useless, it just says " 9V " battery, it does not state the actual voltage never mind the number of cells in the thing.

So now time to discharge it for the second time !

... but this time won't make the same mistake ! Won't leave it go flat at night while I am sleeping ! 

Nope... so will wait until tomorrow. Will start discharging it when I wake up tomorrow, so I can keep an eye on voltage regularly throughout the day as it discharges.
Will make sure to write down exact voltage and time, so I can run the numbers and guesstimate the capacity of the battery.... once it reaches 7.0 Volts, as Rob indicated.

So... see you tomorrow for the next and à priori last installment of the Varta saga !

[Vince]

It is an often repeated stereotype that the Italians build 'em pretty...well, not always.
As there was a rather lengthy list of VTVMs, I think this one was missing. And it could be a looker if they had cared to use different knobs.
On offer on Ebay.de: https://www.ebay.de/itm/325005201290 (NAWTS)

Nope, does not qualify for the VTVM database !
Look, it measures Ohms and Farads ! It's not a VTVM, it's VTMM !! 

[Cerebus]

It is an often repeated stereotype that the Italians build 'em pretty...well, not always.
As there was a rather lengthy list of VTVMs, I think this one was missing. And it could be a looker if they had cared to use different knobs.
On offer on Ebay.de: https://www.ebay.de/itm/325005201290 (NAWTS)

Hmm, that would take more than a 'knob job' to make it pretty. Let's hope that the attention that an Italian would normally put into the exterior went into the function instead - that would be a turn up for the books.

A previous boss of mine, Peter, had a Testarossa, a splurge buy when he sold off a previous company. Fortunately he also had enough left over for a Porsche for himself and a Merc for the wife. Almost every time he decided to bring the Ferrari to work he got at best half way between home and the office - 5 miles tops, probably not even that. I saw the Testarossa parked outside the office perhaps twice, if the Porsche was also missing it was a fairly safe indication that Peter had got a cab from wherever the Ferrari had broken down, and that his Mrs would be turning up in the Merc at the end of the day to take him home. Totally put me off any idea of acquiring a Ferrari of my own.

[mansaxel]

It's not fair to call the American society a "parody"...    the difference is that Scandinavian countries are far more homogeneous than the USA, making the latter more difficult to govern.  Scandinavia doesn't have large sections of society that are deeply religious and suspicious of science, for example.  I find it hard to imagine many Scandinavians putting up heated arguments against vaccines, for example...   And it isn't just a matter of education - it is a cultural / attitude-to-life difference.

These are very good arguments. Thank you.  There are two things I'd like to point out, one of context;

Calling Mnemlandia a "parody" is my perhaps clumsy way to acknowledge his frustration. And a bit of my own.

The other point is one of historical observation;

We in Sweden have more so than other countries in Europe (maybe not so different from Finland, and Iceland, though) been looking longingly at the societal progress made in the USA up to the 70s. We tried to emulate that!  Some of the people who were instrumental in setting themes in the post-war Swedish growth economy (in reality fueled a lot from not having been bombed to shambles and having its complete population mostly unharmed) made frequent study visits to the USA. 

And, we do of course have a bunch of uninformed people too, the party-who-say-they're-not-fascists-but-were-founded-by-a-non-repenting-Waffen-SS-member have about 20% of the vote and make all the other right parties soil their liberal ideals to gain coöperation.  But yeah, we exported a lot of the religious freaks to the US in the 19th century, so the ones who remained are less crazy.

[WastelandTek]

covid school policy rant redacted for brevity

It is increasingly evident that policy responses are more about compliance than science, another example https://winnipeg.ctvnews.ca/i-thought-it-was-a-joke-canada-post-employee-sent-home-for-wearing-n95-mask-instead-of-company-provided-cloth-or-disposable-mask-1.5747301

I am really quite disappointed with myself how long I swallowed the narrative.

[mnementh]

This differs from right now in what way; given the radical right's systematic dismantling of public education, thereby ensuring that only those who can afford private schooling get anything approaching a proper education...?

Ummm... you're making this into a really evil Sophie's Choice here; I think there has to be some better answer than "herd them into the abbatoirs so they're not a drain on future society", which is the ultimate end of such reasoning. I dunno... Maybe tax a rich motherfucker for a change?

EDIT: I mean... we're talking about a nation that took on all comers in 2 World Wars, and pulled together (at home and with our allies) to win, and to make the new world after a better place. Why is it too much to hope that we should again rise to the occasion in the face of such a worldwide disaster...?

mnem
*sick of this failed experiment in antisocial Darwinism*

I'm terribly sorry you live in that parody of a society. What I am talking about is the very careful reasoning of our public health administration (CDC, like, so not hospital operators but more overarching view on population health) on the proper balance between taking preventive measures for short-term and long-term threats. They are not elected (the Director-General is appointed by government and usually is a physician specialised in the field). They have a mission to perform and do that, and during this process they have been very open with the fact that they are modeling this from incomplete data, but also that they are taking a very long perspective on things, and that clashes very clearly with what politicians like to do, come up with catchy phrases people can remember. We are watching them think, and adapt.  Eerie, not the least to the media, who do not understand how to make headlines of this.

What has not been so much adapted over time, is their position that schools are to be kept running as long as possible, because the bad health effects from forcing children out of school have been thoroughly proven earlier. Further, given that the present unpleasantness affects children less, the tradeoff is somewhat easier to motivate.

And, we tax our rich. Not enough, but still. (For income from work, all people pay municipal tax, which is about 32%. If you earn above ~550000 SEK per year, you also pay 20% state tax on the amount above the limit which means that those incomes are taxed at about 52-53%. For capital gains et c, it is not as progressive; there the tax is a flat 30%)

It's not fair to call the American society a "parody"...    the difference is that Scandinavian countries are far more homogeneous than the USA, making the latter more difficult to govern.  Scandinavia doesn't have large sections of society that are deeply religious and suspicious of science, for example.  I find it hard to imagine many Scandinavians putting up heated arguments against vaccines, for example...   And it isn't just a matter of education - it is a cultural / attitude-to-life difference.

I think it's entirely fair.    Many times I've sat on a park bench or waiting for my stop on the bus line... and wondered when my life was going to skip to the commercial break, and we'd see adverts for the sane version of American Society. 

mnem
We hear people squawking about the right to freedom of religion all the time... how about my right to freedom from religion?

[TERRA Operative]

I can send you a bare OCXO PSU PCB, a replica I made of the original one if you like.

If only someone would finally say that about my 5334A!

I don't have a 5334A, but my 5335A came with the OCXO option fitted already. I have a half-baked plan to build my own  voltmeter option for it one day, just for fun. It's pretty low on the to-do list though so one day, some day..

[SilverSolder]

It's not fair to call the American society a "parody"...    the difference is that Scandinavian countries are far more homogeneous than the USA, making the latter more difficult to govern.  Scandinavia doesn't have large sections of society that are deeply religious and suspicious of science, for example.  I find it hard to imagine many Scandinavians putting up heated arguments against vaccines, for example...   And it isn't just a matter of education - it is a cultural / attitude-to-life difference.

These are very good arguments. Thank you.  There are two things I'd like to point out, one of context;

Calling Mnemlandia a "parody" is my perhaps clumsy way to acknowledge his frustration. And a bit of my own.

The other point is one of historical observation;

We in Sweden have more so than other countries in Europe (maybe not so different from Finland, and Iceland, though) been looking longingly at the societal progress made in the USA up to the 70s. We tried to emulate that!  Some of the people who were instrumental in setting themes in the post-war Swedish growth economy (in reality fueled a lot from not having been bombed to shambles and having its complete population mostly unharmed) made frequent study visits to the USA. 

And, we do of course have a bunch of uninformed people too, the party-who-say-they're-not-fascists-but-were-founded-by-a-non-repenting-Waffen-SS-member have about 20% of the vote and make all the other right parties soil their liberal ideals to gain coöperation.  But yeah, we exported a lot of the religious freaks to the US in the 19th century, so the ones who remained are less crazy.

Every country seems to have ~25% "deplorables" that are a burden for the rest to manage...

[VK5RC]

@wastelandtek mine is a 3586C model
The total protrusion is 11.7mm, the thread protrudes 2.6mm, diameter of shaft 3.2mm
See photos below.
If any further information is needed please let me know, Rob

[mansaxel]

It is an often repeated stereotype that the Italians build 'em pretty...well, not always.
As there was a rather lengthy list of VTVMs, I think this one was missing. And it could be a looker if they had cared to use different knobs.
On offer on Ebay.de: https://www.ebay.de/itm/325005201290 (NAWTS)

And here, this one: (NAWTS)



turned up the other day. Philips indeed, but built here (like most of the counters, but much earlier) by the Swedish branch.

Edit: I with some horror observe that the mains connector and the HF probe connector are each others mates, so that the cable connectors on mains cable and HF probe in all likelyhood are mechanically  compatible. I do not think that it would be a good idea to try.

[Specmaster]

covid school policy rant redacted for brevity

It is increasingly evident that policy responses are more about compliance than science, another example https://winnipeg.ctvnews.ca/i-thought-it-was-a-joke-canada-post-employee-sent-home-for-wearing-n95-mask-instead-of-company-provided-cloth-or-disposable-mask-1.5747301

I am really quite disappointed with myself how long I swallowed the narrative.

I think you nailed it with that article, the thing is as far as I can see, both the USA and the UK administration were both very slow to react in the first instance and by the time they began to take the virus seriously, the death toll had already risen to being among the very worst in the world, which reflected badly on both nations considering their relative standing in the world. I think they are looking for a scapegoat to pin the huge death toll on and are hoping that maybe other countries that did follow the science and used all their powers to control movement of people, who are after all, the means of distribution, have so far managed to really suppress the spread of the virus, have relapse and major outbreaks. That then would take the heat of our authorities.

Certainly here in the UK, they have managed to convince enough of the public that the "experts" are wrong, you only have to look at Brexit for that, hugely damaging to our way of life and economy, which the experts all predicted and warned us about, but we still opted for Brexit. Part of that has to be down to the way that education over the years has been dumbed down unless, of course, as has been already been said, you were wealthy enough to have the advantage of a private education.

Like it or not, we in the UK and the States it seems still have a class system and this is a way of keeping that system in place.

[Neomys Sapiens]

I can send you a bare OCXO PSU PCB, a replica I made of the original one if you like.

If only someone would finally say that about my 5334A!

I don't have a 5334A, but my 5335A came with the OCXO option fitted already. I have a half-baked plan to build my own  voltmeter option for it one day, just for fun. It's pretty low on the to-do list though so one day, some day..

The 5334 differs in that it needs that unobtainium adapter board in order to fit an OCXO.
I wonder whether your envisaged voltmeter option can be made to utilize higher resolution that the original one. The places in the display are there!

[Kosmic]

Hi:

I'm here once again to ask probably stupid questions!

The Keithley 181 nanovoltmeter arrived today. After opening it to change the mains voltage to 230V as well as to inspect everything is ok, I power it up. I measure some normal voltages and everything is fine. Here comes the weird thing. I try to zero the meter by connecting the input cable and shorting it. When I made this measurement, the unit had been powered on for 40 minutes with the cable connected in order to let everything stabilize. And yet, look at that result! VERY far from zero. Is that normal?

I also tried a small piece of copper shorting the inputs. Letting it stabilize for 10 minutes gave me a similar result.

I'm unfamiliar with low level voltage measurements. I've watched Marco Reps video and he's able to get very close to zero. I've taken the same precautions and yet it doesn't seem to matter.

I would greatly appreaciate any advice

Might come from your test lead. Doesn't look original. The connector should be silver and cable black and relatively thin. Keithley was using a low noise triax cable.

Like so


When I had a Keithley 181, I was able to get +-60nV with my home made test lead.
https://www.eevblog.com/forum/metrology/possible-low-thermal-emf-connectors/msg1936489/#msg1936489

[mnementh]

...And, we do of course have a bunch of uninformed people too, the party-who-say-they're-not-fascists-but-were-founded-by-a-non-repenting-Waffen-SS-member have about 20% of the vote and make all the other right parties soil their liberal ideals to gain coöperation.  But yeah, we exported a lot of the religious freaks to the US in the 19th century, so the ones who remained are less crazy.

Every country seems to have ~25% "deplorables" that are a burden for the rest to manage...

Difference here is that even tho they are by far a minority, they've managed to wrest control away from the adults...  You know that Twilight Zone episode with a whole town being terrorized by the whims of an omnipotent 8-year-old played by Billy Mumy?

That's what it feels like. 

mnem
 

[Vince]

Still sorting my stuff.... I discover things !

Found a pink shoe box, had no idea what the hell it could contain..... just opened it up... something wrapped inside, can't see what it is.... unwrap it... ohhhh.....  a Tek plug-in ! 

Ah now that rings a bell, my good friend in Germany sent it to me gratis a few years ago. Just a modest and very common Type CA plug-in, missing 4 tubes as well, four 12AT7.. surprise surprise 

So not much value but was nice of him to give it to me, can use it for parts 

Makes me think of Papa Smurf and the similar plugins he is working on. Where is Papa Smurf ?


Back to unboxing and sorting stuff....

[WastelandTek]

@wastelandtek mine is a 3586C model
The total protrusion is 11.7mm, the thread protrudes 2.6mm, diameter of shaft 3.2mm
See photos below.
If any further information is needed please let me know, Rob

Thank you so much.

Yes, from this I can glean that the number I need is 9.1mm, 0.4mm from 3/8" which I am going to guess is what HP was shooting for when they cut these down.

I really appreciate the help!

I don't suppose anyone has a "grey era" HP knob for a 1/8" shaft in their knob bin??

[vk6zgo]

It is an often repeated stereotype that the Italians build 'em pretty...well, not always.
As there was a rather lengthy list of VTVMs, I think this one was missing. And it could be a looker if they had cared to use different knobs.
On offer on Ebay.de: https://www.ebay.de/itm/325005201290 (NAWTS)

Hmm, that would take more than a 'knob job' to make it pretty. Let's hope that the attention that an Italian would normally put into the exterior went into the function instead - that would be a turn up for the books.

A previous boss of mine, Peter, had a Testarossa, a splurge buy when he sold off a previous company. Fortunately he also had enough left over for a Porsche for himself and a Merc for the wife. Almost every time he decided to bring the Ferrari to work he got at best half way between home and the office - 5 miles tops, probably not even that. I saw the Testarossa parked outside the office perhaps twice, if the Porsche was also missing it was a fairly safe indication that Peter had got a cab from wherever the Ferrari had broken down, and that his Mrs would be turning up in the Merc at the end of the day to take him home. Totally put me off any idea of acquiring a Ferrari of my own.

I had a workmate with a Triumph Stag.............

[Vince]

Getting better and better... Just excavated this little thing... the dim bulb tester I made a few years ago, still looking good 

Now I can use that when doing the initial power up of unknown vintage gear... but might need a more powerful bulb than this one probably...

[Specmaster]

Getting better and better... Just excavated this little thing... the dim bulb tester I made a few years ago, still looking good 

Now I can use that when doing the initial power up of unknown vintage gear... but might need a more powerful bulb than this one probably...

Thats really neat, makes mine look rough 

[Vince]

That one was originally supposed to be rough... made from a scrap crap pine plank I had in the garage.

But I thought hey, would take only a few minutes to improve on it so why not do it.

Grabbed my big #7 wood plane to make the deck flat and true, then fine grit paper to make it super smooth. Then grabbed a smaller #4 plane to chamfer the edge all around, just to add some style and refinement... some chiseling here and there for the smaller details... a couple coats of oil to protect from dust and dirt over time, and that's about it... cost nothing to do and took only a few minutes ! 

[TERRA Operative]

I can send you a bare OCXO PSU PCB, a replica I made of the original one if you like.

If only someone would finally say that about my 5334A!

I don't have a 5334A, but my 5335A came with the OCXO option fitted already. I have a half-baked plan to build my own  voltmeter option for it one day, just for fun. It's pretty low on the to-do list though so one day, some day..

The 5334 differs in that it needs that unobtainium adapter board in order to fit an OCXO.
I wonder whether your envisaged voltmeter option can be made to utilize higher resolution that the original one. The places in the display are there!

If you have a picture of the adapter board you need, front and back, I can design one up and send you gerbers to get made in your friendly neighbourhood Chinese PCB fab.

I haven't looked too deep into the 5335A voltmeter, but it probably wouldn't be toooo hard to at least improve the specifications with modern parts at the very least.