Test Equipment Anonymous (TEA) group therapy thread

[0culus]

I decided to try the old Dumont 274-A Oscillograph (I guess the word oscilloscope was not invented yet  ) I got part of the lot I fetched earlier this week. The inside was kind of clean but was still waiting for an explosion when I plugged-in the beast. I was astonished to see that it was kind of working. Probably need a good recap though

Talking about caps I'm probably too young but it's the first time I see those brown capacitor in wax. They look like wine bottle cork.

Are you going to clean it up and get rid of the wax caps? Might not be the most useful scope by modern standards, but could still be a cool "conversation starter" in the lab. 

Also interesting to contrast this "oscillograph" with the stuff Tektronix was making just a decade or two later and marvel about how fast 'scopes developed.

[bitseeker]

For things like this I bought a cheap USB-to-GPIB converter:



Works fine under Linux as a serial device. Haven't done much with it, though. So I don't know if or how the more 'interesting' parts like SRQ are working.

I'm not sure about the more advanced functionality, but in general, you should be fine if you're writing your own software to interface with it.

[bitseeker]

Speaking of making cakes: here are some examples of my production (this is another hobby of mine) 



And yes, I DO live southern of the river Main. 

Woah, BU508A! That's a dangerously impressive other hobby.

[bitseeker]

No, I don't. I'm not good enough for them. But that's okay, because important to me is that the people like my cakes.
My reward is looking on their happy faces.

Seeing them does provide some happiness, but not like eating them does.

Edit: Just for med: guess, what kind of cake this is:   

Black Forest cake, of course. I was in the Black Forest a few years ago, watched a baker there make one with lots of kirschwasser and even more whipped cream. Then, I ate some of it. Yum!

[bitseeker]

I decided to try the old Dumont 274-A Oscillograph

Added to POI

[worsthorse]

Tuesday evening's find, from a trash barrel being used as storage for various types of electronics and cables.



Yes that's a Heath Voltage Reference Source from the M-E Lab Components series



It was, in the day, a pretty good voltage reference, accuracy "as allowed by 0.1% resistors" as it says in the catalog entry.







I haven't powered it up because one of the fuses, and the latching fuse cover are missing. The slow blow fuse on the line side is interesting:



Other than the catalog page and a webpage copy of the calibration procedure, I haven't found a manual or much else on it. I do know that it was produced for one year, in 1970.

I will probably make sure it works, calibrate it, play with it a bit to see how accurate it is and then ask if anyone more interested in collecting Heath gear than me wants to buy it.

And how I came to to be introduced to the trash barrel, well that's a story for another evening.

[bitseeker]

Your TEAcquisition skills are making us look like slackers, wch!

(Added to the POI)

[Ero-Shan]

YEA ME! Just won this fine example of a later HP 427A, looks to be in very good condition.
https://www.ebay.com/itm/Vtg-Hewlett-Packard-Voltmeter-427A-Volt-Meter-Tester-Excellent-Powers-Up-HP-/183787763383?_trksid=p2349526.m4383.l10137.c10&nordt=true&rt=nc&orig_cvip=true#viTabs_0

Damn! There was a 475 on German eBay that I wanted. And (once more) simply forgot to bid! I would have paid quite a bit more than the winning did. Although he might have topped me anyway, that was a very good chance that I missed. I feel miserable now. 

[med6753]

I decided to try the old Dumont 274-A Oscillograph (I guess the word oscilloscope was not invented yet  ) I got part of the lot I fetched earlier this week. The inside was kind of clean but was still waiting for an explosion when I plugged-in the beast. I was astonished to see that it was kind of working. Probably need a good recap though

Talking about caps I'm probably too young but it's the first time I see those brown capacitor in wax. They look like wine bottle cork.

Are you going to clean it up and get rid of the wax caps? Might not be the most useful scope by modern standards, but could still be a cool "conversation starter" in the lab. 

Also interesting to contrast this "oscillograph" with the stuff Tektronix was making just a decade or two later and marvel about how fast 'scopes developed.

Judging by the type of vacuum tubes used......all octal types and using a later obsolete "80" type for the rectifiers....would place this scope late 1930's, early 1940's.

The non-linear sweep is definitely caused by a leaky cap in the sweep circuit. All those tubular caps, especially the brown wax ones, are no good, guaranteed. Although even when everything was up to snuff these old scopes weren't very linear.   

[med6753]

YEA ME! Just won this fine example of a later HP 427A, looks to be in very good condition.
https://www.ebay.com/itm/Vtg-Hewlett-Packard-Voltmeter-427A-Volt-Meter-Tester-Excellent-Powers-Up-HP-/183787763383?_trksid=p2349526.m4383.l10137.c10&nordt=true&rt=nc&orig_cvip=true#viTabs_0

Damn! There was a 475 on German eBay that I wanted. And (once more) simply forgot to bid! I would have paid quite a bit more than the winning did. Although he might have topped me anyway, that was a very good chance that I missed. I feel miserable now. 

Sorry, but you can't have mine. 

[0culus]

I decided to try the old Dumont 274-A Oscillograph (I guess the word oscilloscope was not invented yet  ) I got part of the lot I fetched earlier this week. The inside was kind of clean but was still waiting for an explosion when I plugged-in the beast. I was astonished to see that it was kind of working. Probably need a good recap though

Talking about caps I'm probably too young but it's the first time I see those brown capacitor in wax. They look like wine bottle cork.

Are you going to clean it up and get rid of the wax caps? Might not be the most useful scope by modern standards, but could still be a cool "conversation starter" in the lab. 

Also interesting to contrast this "oscillograph" with the stuff Tektronix was making just a decade or two later and marvel about how fast 'scopes developed.

Judging by the type of vacuum tubes used......all octal types and using a later obsolete "80" type for the rectifiers....would place this scope late 1930's, early 1940's.

The non-linear sweep is definitely caused by a leaky cap in the sweep circuit. All those tubular caps, especially the brown wax ones, are no good, guaranteed. Although even when everything was up to snuff these old scopes weren't very linear.   

I was reading a bit about Dumont's history. It seems that the first Tektronix 'scope featuring the timebase we think of today basically killed their dominance of the market. I'm not sure I fully understand how the Dumont oscillograph worked as far as horizontal...

[0culus]

https://www.oscilloscopemuseum.com/oscilloscope-dumont-274a-s1205.html

Looks like this site has some manuals.

[med6753]

That Dumont scope used a dead simple recurrent sweep circuit and that type of circuit was used in post WW2 "hobby" scopes for the TV repair market. Heath scopes used that type of circuit right up into the 1960's. You set your rough horizontal sweep then adjusted the fine horizontal until the sweep locked....or I should say...at least slowed down so you could view it. It never locked for long, they would slowly drift.

Tektronix developed the much superior triggered sweep which is standard today on all analog and digital scopes.

[med6753]

https://www.oscilloscopemuseum.com/oscilloscope-dumont-274a-s1205.html

Looks like this site has some manuals.

That site says it dates to 1948. I think it's earlier than that.

[0culus]

That Dumont scope used a dead simple recurrent sweep circuit and that type of circuit was used in post WW2 "hobby" scopes for the TV repair market. Heath scopes used that type of circuit right up into the 1960's. You set your rough horizontal sweep then adjusted the fine horizontal until the sweep locked....or I should say...at least slowed down so you could view it. It never locked for long, they would slowly drift.

Tektronix developed the much superior triggered sweep which is standard today on all analog and digital scopes.

Interesting. I guess I'm too young to have encountered one of those 'scopes. 

https://www.oscilloscopemuseum.com/oscilloscope-dumont-274a-s1205.html

Looks like this site has some manuals.

That site says it dates to 1948. I think it's earlier than that.

Perhaps they were made till 1948? Would need to find a catalog to find out for sure.

[med6753]

Read all about Dumont here. Not only did they make test equipment but they were also a TV broadcast pioneer but were muscled out by CBS and NBC and went out of biz in 1956.

https://en.wikipedia.org/wiki/DuMont_Television_Network

[Ero-Shan]

So you thought it was finally over? Nah, you were wrong. It ain't over 'till the fat lady sings!

And the saga continues ...

... with the Solartron 7050 and its lookalikes.

The 2 of them are not exactly the same. Do you spot the difference?



Yes, the upper one's almost spot on, while the lower one is a wee bit below.
No, of course it's the different displays. I can't remember having ever seen the breed between the standard bar displays (lower) and the dotted ones of some 70ies HP gear. To me this is absolutely gorgeous!

Resistance measurement didn't work at all with the upper, the numbers were all over the place. OK with the instrument at the bottom.

There's a marked scarceness of controls: Power switch and function selector, the latter with a cheapish appearance. Not much picture fodder, so let us remove the case (which is easily done):



A little more cramped than the 19″ models, but mostly fine.
Solartron uses some novel scheme for interconnecting the boards. These contact combs (lacking a better word) can be slid out and back again. This, however, gets a bit tricky when you can't see the contacts, as this comb is easily tilted a bit and misses them. It also means that operating the instrument while the boards are separated (so you have easy access to the base PCB) is not possible.



Without the daughter board:



On to the display:



These components look a bit fragile. And the front is not even flat!

I like this one. 5.1 digits (yep, max is 109999). The display sets it apart, the form factor allows finding a space for it. The non-working resistance measurement needs to be looked at (it's not the caps; they're all fine). Kinda neat.

But wait! It's got a step-brother. You have to look closely to see the difference: 7051 instead of 7050.



This one has a larger daughter PCB, the mother PCB seems to be the same. I have no idea what the real difference is.



But wait! It's also got a little brother that is missing the last digit. This one is called 7140. According to the service manual, the 7050, 7140 and 7144 belong to the 7050 family, but not the 7051. 



This concludes the Solartron extravaganza. Now that the fat lady has done her part, the final curtain falls and I can go back to my lazy, slow pace. 

Thanks all of you for watching and not complaining about all those pics.

[med6753]

A little more cramped than the 19″ models, but mostly fine.
Solartron uses some novel scheme for interconnecting the boards. These contact combs (lacking a better word) can be slid out and back again. This, however, gets a bit tricky when you can't see the contacts, as this comb is easily tilted a bit and misses them. It also means that operating the instrument while the boards are separated (so you have easy access to the base PCB) is not possible.

Tek used same type interconnects on the Inverter/Regulator board in the 2465. Also the same concerns. Use care when reinserting them and also can't operate the PSU when the boards are separated.

[BU508A]

Black Forest cake, of course. I was in the Black Forest a few years ago, watched a baker there make one with lots of kirschwasser and even more whipped cream. Then, I ate some of it. Yum!

  100 gummipoints for bitseeker. 

If we should ever do a TEA meeting in real life, I promise, I'll bring some cakes of mine.

[Ero-Shan]

Now for a small relief.

Klein+Hummel Röhrenvoltmeter (VTVM) RV-12. According to radiomuseum.org it is of 1962 vintage.

Which company dealing with electronics did not offer their interpretation of the (presumably) same basic design?
Klein+Hummel, makers of studio and HiFi ecquipment, were assimilated in 2009 by Sennheiser, but they had and still have an excellent reputation.

You guessed right this time, again with the boring 10 V reference:



Note that the necessary 1 MΩ resistance is inserted. That looks rather good.
Resistances measurements are, well forget it. The needle points in the general direction of the value, but that's it.

The back of the steel case hasn't much to show but the single screw that holds it all together and the fuse holder/voltage selector and the power switch. Power cords were usually not detachable in those days. Which I don't like, as they need extra room when storing the device and they tend to tangle up with others.



Not too many surprises inside at first look, dust & rust:



Of course, after umpteen years in storage, the battery for Ohms draws some interest:

That is surely an 'interesting' design of a battery holder! The resistor is directly soldered to the battery cell. The clamp is fixed. The strain relief of the power cord can also be seen. I guess that is not the original technique.

The battery with the plastic spacer (or collar) and a slightly rusty spring. 



Despite some rust, that 20 year old battery did not leak and is still as good as new. Anyway, I decide to forget about Ohms here altogether, so I don't have to worry about the battery. If need be, I have means to measure resistance. 

Although this machine is heavy metal inside out, it is not connected to protective earth. Looking at the flimsy insulation of the transformers primary wires (mustn't they be doubly insulated for Protection Class II?) sends a slight shiver up my spine. But then, why should they suddenly make a short to the chassis? That case is quite effective in protecting them.

And here is my second RV 12 (without dash), likely somewhat newer (and these knobs are never ever original!). Alas, it's movement window is shattered. And the measurement is noticeably off:



With this, there are signs of a previous battery leakage (but no battery). The power cord is certainly not the original (it looks like typical Telefunken) and there is absolutely no strain relief whatsoever!



The back either shows the instrument's schizophrenia, as it says 'RV-11', or they got swapped at birth.

[tggzzz]

Solartron uses some novel scheme for interconnecting the boards. These contact combs (lacking a better word) can be slid out and back again. This, however, gets a bit tricky when you can't see the contacts, as this comb is easily tilted a bit and misses them. It also means that operating the instrument while the boards are separated (so you have easy access to the base PCB) is not possible.

The 7075 is worse

Imagine having the red plastic carrier between the circuit boards, and not being able to see between the boards without removing them from the case.

Separating the boards is easy, reassembling them requires some trial and error.

[Ero-Shan]

Solartron uses some novel scheme for interconnecting the boards. These contact combs (lacking a better word) can be slid out and back again. This, however, gets a bit tricky when you can't see the contacts, as this comb is easily tilted a bit and misses them. It also means that operating the instrument while the boards are separated (so you have easy access to the base PCB) is not possible.

The 7075 is worse

Imagine having the red plastic carrier between the circuit boards, and not being able to see between the boards without removing them from the case.

Separating the boards is easy, reassembling them requires some trial and error.

I really wonder what those designers think when they're choosing solutions like these. In manufacturing you can cope with that by using specialized tooling, but when they need repairs?

And these instruments are meant to be repaired! I cannot think of a viable excuse. Oh, sure I can: cost.

[med6753]

Now for a small relief.

Klein+Hummel Röhrenvoltmeter (VTVM) RV-12. According to radiomuseum.org it is of 1962 vintage.

And you can tell where they got their inspiration. It's almost a direct copy of the Heath VTVM's of the same era.

[Specmaster]

Now for a small relief.

Klein+Hummel Röhrenvoltmeter (VTVM) RV-12. According to radiomuseum.org it is of 1962 vintage.

And you can tell where they got their inspiration. It's almost a direct copy of the Heath VTVM's of the same era.

By comparison, Heathkit used lighter frames and power transformers though.

Sent from my POT-LX1 using Tapatalk

[mnementh]

Sounds more promising for low speed DC fans  Still waiting on mine but I think it will be taking the scenic route via two states capitals due to it and my origin. 

Playing amateur Ham today my little baofeng turned up - stock antenna is  so I have used most of my coax test leads joined to get it up a small pole  Hitting a repeater 30+km away so not terrible even with that dodge. Discone and a proper pole in the near future for this and the SDR playing.

And this slightly crusty PAT box I scored for not to much. Scrubbing brush and industrial detergent time.

edit: Photo of what is under the bonnet. ATMEGA84 based. Much safer to scrub the outer with the electrics out.

So... a slightly more automated and lower voltage version of a Megger? Looks like it's intended to be a workplace safety type bit of equipment; test your power tools in the shop on a periodic basis to make sure your grinder-monkeys aren't killing themselves with ghetto-rigged or otherwise abused tools, right? Over here that would be the demesne of an OSHA-compliance auditor...

Or do you guys still have some form of public safety office that actually audits the safety of appliances that are used in public places? 

I decided to try the old Dumont 274-A Oscillograph (I guess the word oscilloscope was not invented yet  ) I got part of the lot I fetched earlier this week. The inside was kind of clean but was still waiting for an explosion when I plugged-in the beast. I was astonished to see that it was kind of working. Probably need a good recap though

Talking about caps I'm probably too young but it's the first time I see those brown capacitor in wax. They look like wine bottle cork.

         

Are you going to clean it up and get rid of the wax caps? Might not be the most useful scope by modern standards, but could still be a cool "conversation starter" in the lab. 

Also interesting to contrast this "oscillograph" with the stuff Tektronix was making just a decade or two later and marvel about how fast 'scopes developed.

I'd be tempted to keep that beast original, and only switch it on occasionally when I felt brave enough to risk the fireworks & stinkbomb. Though it's obviously already been butchered with a BNC connector, so probably a pointless exercise. 

I remember reading an article in one of the antique radio forums back when... about a fellow who would warm up those wax caps, cut the outer layer off, stuff modern caps inside and pour the whole thing full of new wax. He even got to the point where he started making them for sale with small labels identifying them as period-correct "replica" parts. Talk about devotion to your hobby...

Tuesday evening's find, from a trash barrel being used as storage for various types of electronics and cables.

   Yes that's a Heath Voltage Reference Source from the M-E Lab Components series   (Snippity)   I will probably make sure it works, calibrate it, play with it a bit to see how accurate it is and then ask if anyone more interested in collecting Heath gear than me wants to buy it.

And how I came to to be introduced to the trash barrel, well that's a story for another evening.

Yummy analog goodness from the golden age of American Electronics!     Please, do tell!

Now for a small relief.   Klein+Hummel Röhrenvoltmeter (VTVM) RV-12. According to radiomuseum.org it is of 1962 vintage.

Which company dealing with electronics did not offer their interpretation of the (presumably) same basic design?
Klein+Hummel, makers of studio and HiFi ecquipment, were assimilated in 2009 by Sennheiser, but they had and still have an excellent reputation.

You guessed right this time, again with the boring 10 V reference:

   Note that the necessary 1 MΩ resistance is inserted. That looks rather good. (SNIP)

Even more analog goodness; this time from the vicinity of the Rhein! 

So you thought it was finally over? Nah, you were wrong. It ain't over 'till the fat lady sings!

And the saga continues ...  ... with the Solartron 7050 and its lookalikes.   The 2 of them are not exactly the same. Do you spot the difference?

   (SNIP)   This concludes the Solartron extravaganza. Now that the fat lady has done her part, the final curtain falls and I can go back to my lazy, slow pace. 

Thanks all of you for watching and not complaining about all those pics.

Not at all... this has been a delicious repast to mull over my morning hambled eggs & coffee. Thank you all for the parade! 

mnem