Test Equipment Anonymous (TEA) group therapy thread

[0culus]

Playing around with programs on my 8568B now that it is functioning HP-IB. I successfully got a third order intermod product program from an old HP product note to run. It automates the measurement nicely, and selects the optimal attenuator settings and stuff for you.

[psykok]

A myriad rabbit holes in a single boat anchor. Wowzers.

And the Peanut Galley busts my balls every time I get new TE and I perform a re-cap. Not only did he replace all the electrolytics and tants but ALL the carbon comp resistors too. 

Huge work but this unit is definitely  worth  it!


ALex

[vk6zgo]

First off, to all the Canadians here, happy thanksgiving!

When Mnemnth and I met up for coffee the other day and we were chatting about test equipment and all, I was showing pictures of some of the locally built oddities for which there’s either very little or no documentation out there.  Back in late June 2017 I found a listing for an HP 523D counter nearby and I was able to get in touch with the gentleman selling it and dropped by on my way to work to pick it up. It was listed for $40 but while I was on my way there, he decided to give it to me along with this Measurement Engineering Ltd. signal generator free of charge since they’d been listed for several months and since nobody had expressed any interest, were going to be put in his town’s ewaste recycling in a few weeks had I not called.

I brought both into work that afternoon since one of the other guys there enjoys vintage stuff like this and we spun up the HP 523D counter and put the columnar displays through their paces with a handheld signal generator since it was demonstrated working when I picked it up, and took the cover off the MEL.  There’s a smudged stamp inside that almost implies a 1939 build year and the style of the cabinet tends to agree but then I wonder if it was made post war out of surplus parts because when I researched the company, there were a a couple archival newspaper articles I found online about how much the company liked moving to Arnorior, which is the location given on the front panel, and this was a post war article.  The only other thing I could find was a trademark history that shows the Measurement Engineering Ltd. name and logo were bought by Canadian Stackpole who registered it and then renewed it once, then ultimately let it lapse in 1984.  We didn’t attempt to power it up because it clearly needs an electrical restoration but one of the guys at work was saying that it’s like some of the equipment he worked on when he was a new employee that was built by defunct companies that have little or no record that they ever existed online.  Not everything is on the internet.

Here are some pictures:



Built in Arnprior, Ontario and last calibrated a very, very long time ago by ITT Canada who may, at one time, have had documentation on this machine.



The top deck shows a tube complement that I believe is all pre-war.  When I looked up the introduction dates on the tubes used in this machine back in 2017 when it was first given to me, they were all pre-war with one (forgotten which) that scraped in with a 1939 introduction date.  So the tube compliment and the style of the case plus the one fuzzy stamp inside the chassis suggests a build date in 1939, but, on the other hand, that doesn't square with the one newspaper article from the early fifties I found that talked about how Measurement Engineering Limited liked moving to Arnprior as if it had just happened.  Without any other information that I could find out there, the build date and approximate age are a mystery.  But look at that beautiful four gang tuning capacitor and the transformers and choke!



The underside of the chassis.  Those heavy porcelain insulators are beautiful as is the looming job on the wiring.  Correct me if I'm wrong but I thought the standard Wein bridge oscillator and Hewlett-Packard (and companies that cloned the HP circuit) used a single lightbulb but MEL's circuit uses two of them so it may not be an exact clone.

This signal generator's been sitting on the shelf in my boat anchor collection since I got it but since having coffee with Mnemnth and showing pictures, I've started to get an itch to pull this off the shelf and do an electronic restoration on it to get it running in a couple of weeks once the autumn yard work is out of the way and it starts getting crappier outside.  Is there any interest in seeing pictures of the restoration process?

The metal tubes look surplus, & the resistor packages are pretty common 1950s---------1930s would more likely use "body, tip, & spot" colour coding, & the resistors themselves would be more "dog bone" shaped.

There were also still quite a few designs which used octal tubes in the 'Fifties.
For instance, the "RF exciters" used in the mid 1950s STC broadcast transmitters at my old job were all octal tubes.

Unless the device really needed to be small, or there was some other complicating reason, there was little reason to change what may have been a decades old, but effective design.

During WW2, countries ramped up their production & produced millions of octal tubes, so they were available after that conflict at prices hobbyists & smaller manufacturers could only have dreamed of prewar.

Marconi in the UK, right into the 1950s seemed to have been in the habit of over producing or procuring components for years, so that "archaic looking" but still perfectly functional parts were still turning up in their equipment in the 1970s.

[mansaxel]

6206B update:

The power supply is largely OK. It helps if the user installs the prescribed strappings on the barrier strip at the rear.

Also, a sense cable for the - binding post was broken off the PCB, reattached and OK.

Remaining to do:

• Verify that the voltage range switch works. Adjusted voltage above 30V remains if 30/60V range is switched.
• Fix the range / meter switch mechanically. It appears mostly operative electrically. (but see above)
• Final cleaning and reassembly.
• Edit: And, of course adjustment per manual.

Teaser on mains cable replacement attached.

[BU508A]

6206B update:

The power supply is largely OK. It helps if the user installs the prescribed strappings on the barrier strip at the rear.

Also, a sense cable for the - binding post was broken off the PCB, reattached and OK.

Remaining to do:

• Verify that the voltage range switch works. Adjusted voltage above 30V remains if 30/60V range is switched.
• Fix the range / meter switch mechanically. It appears mostly operative electrically. (but see above)
• Final cleaning and reassembly.
• Edit: And, of course adjustment per manual.

Teaser on mains cable replacement attached.

* BU508A is adding to the list:

• replacing electrolytic capacitors
• replacing tantalum capacitors
• replacing carbon resistors

 

[Specmaster]

A myriad rabbit holes in a single boat anchor. Wowzers.

And the Peanut Galley busts my balls every time I get new TE and I perform a re-cap. Not only did he replace all the electrolytics and tants but ALL the carbon comp resistors too. 



 

Whats next, all the semiconductors as well 

[BU508A]

My bet would go to the electromechanical parts. Relays etc.

[bd139]

Might as well make some new boards up if you're going that far 

[psykok]

Might as well make some new boards up if you're going that far 

don't laugh that  is exactly  what is happening in the video.

[bd139]

That'll teach me for skipping through it 

[VK5RC]

Sounds a bit like granpa's axe story. Replaced the handle so many times, then the head - but it still is grandpa's axe!

[AVGresponding]

Looks like I've won another HP counter to count all the other counters  and a second digital AVO.   

David

Ah so that was you that survived my sniping attempt. I feel no guilt as I was also the first bidder.

Glad it went to someone on here, in all honesty my main purpose in bidding on it was to try and save it from the nixie clock pendejos.

If I had won, I would then have had to bid again on the Dana 5000, which went to the second bidder for £1.20...

[mansaxel]

6206B update:

* BU508A is adding to the list:

• replacing electrolytic capacitors
• replacing tantalum capacitors
• replacing carbon resistors

 

As usual, there is a Einstürzende Neubauten quote for that: "Nicht unbedingt, aber vielleicht" (not unconditionally, but perhaps). If the device won't meet specifications at the verification / calibration / adjustment step, there will be a need to perform fault finding operations. If it meets specification, it -- by definition -- is OK.

Yes, it's sort of the anti-med statement, but that's how I do things 

[med6753]

My bet would go to the electromechanical parts. Relays etc.

The special relays are unobtanium.

[BU508A]

My bet would go to the electromechanical parts. Relays etc.

The special relays are unobtanium.

Yes, but he got replacements for the more mundane ones.

[med6753]

6206B update:

* BU508A is adding to the list:

• replacing electrolytic capacitors
• replacing tantalum capacitors
• replacing carbon resistors

 

As usual, there is a Einstürzende Neubauten quote for that: "Nicht unbedingt, aber vielleicht" (not unconditionally, but perhaps). If the device won't meet specifications at the verification / calibration / adjustment step, there will be a need to perform fault finding operations. If it meets specification, it -- by definition -- is OK.

Yes, it's sort of the anti-med statement, but that's how I do things 

IMHO that's valid only if you perform a verification, such as an extended burn-in. If you follow my many restorations you'll see that I've had numerous instances where a repaired/calibrated device has failed a burn-in and requires additional repair. The recent Type 310A is an excellent example of that. The HV took the dump during a burn-in cycle.

[Saskia]

My bet would go to the electromechanical parts. Relays etc.

The special relays are unobtanium.

just paint them blue

have to fix the "low cost" audio streamer, it has lost its marbles (bios settings) during transport and also only sporadically finds its Wifi. Does no longer recognize the friggin' USB port.

nasty tear down will follow. But first try work around with Toslink ...

[mansaxel]

IMHO that's valid only if you perform a verification, such as an extended burn-in. If you follow my many restorations you'll see that I've had numerous instances where a repaired/calibrated device has failed a burn-in and requires additional repair. The recent Type 310A is an excellent example of that. The HV took the dump during a burn-in cycle.

...which took place after you'd replaced all the PSU caps (and they most likely aren't positively related). I think we can agree that the HV procedure you're performing is a case of reactive repair, something I of course wholly approve of, in response to a documented malfunction, whereas IMNSHO shotgunning caps is about overinterpreting statistics, not reactive repair. 

(Exception is of course given, with  at that, if you sell the badly aged ones as "extra vintage" to the Audiophools for lulz, then it is poetic justice.)

[bd139]

Ok HM605 is dealt with. New bridge rectifier installed at lunch and it’s burning in for a bit. Trace is a lot sharper and if you turn the brightness up now it doesn’t drop out any more.

Edit: quite surprised at this. Now the amplitude is gone because, quite frankly it's being hammered here but it's still triggering fine!



Signal source:



Not bad for a 60MHz crate!

[mnementh]

https://www.amazon.ca/MatrixPad-S8-Android-1280x800-GMS-Certified/dp/B0813VL2K8/

Prime Day let me down... I was looking for a deal on a decent 10" tablet for the bedside; best they had was 2X or 3X the price of this for similar stats. I really wanted a Lenovo Yoga or Tab M10, but they're just not offering any deals since the COVID lockdown.

I sucked it up and ordered one of these; 2GB RAM, well-rated and GMS-certified for US$62 Prime next-day means I can have something to try until the Christmas deals start to show up. Quad-core MediaTek means it won't be any kind of a rocketship, but review say the stats are legit, so at least this one shouldn't be one of the hacked POS units with 1GB/8GB.

What yummy deals do you guys in Dumbfuckistan have today...?

mnem

[bd139]

In little-dumbfuckistan here. Nothing good. All trash. I was hoping to pick up some bits for my eldest’s Christmas present (gaming pc)

[Kosmic]

A myriad rabbit holes in a single boat anchor. Wowzers.

And the Peanut Galley busts my balls every time I get new TE and I perform a re-cap. Not only did he replace all the electrolytics and tants but ALL the carbon comp resistors too. 



 

Whats next, all the semiconductors as well 

Look like it's a bit too much. By changing perfectly fine components you risk damaging the board.

As for Carbon comp resistors, yes they drift but they were probably not selected for their precision nor stability. But if they cooked the board, it might be a good idea to install bigger one and try to distance them from the PCB.

[mnementh]

https://www.amazon.ca/NanoVna-Analyzer-Measuring-Parameters-Standing/dp/B089CNMD4V

Quick Thumbs-up/Thumbs-down guys: Would you spend US$81 to get a clone NanoVNA-V2 (small screen) with battery and Prime next-day?

mnem
 

[mnementh]

A myriad rabbit holes in a single boat anchor. Wowzers.

And the Peanut Galley busts my balls every time I get new TE and I perform a re-cap. Not only did he replace all the electrolytics and tants but ALL the carbon comp resistors too. 



 

Whats next, all the semiconductors as well 

Look like it's a bit too much. By changing perfectly fine components you risk damaging the board.

As for Carbon comp resistors, yes they drift but they were probably not selected for their precision nor stability. But if they cooked the board, it might be a good idea to install bigger one and try to distance them from the PCB.

As much crap as he changed... I'd be more concerned that its validity as a reference standard is compromised. And I bet a cal lab visit on that mofo is a small fortune.

mnem
 

[tggzzz]

As for Carbon comp resistors, yes they drift but they were probably not selected for their precision nor stability. But if they cooked the board, it might be a good idea to install bigger one and try to distance them from the PCB.

Possibly selected for their ability to survive short-term overload - which might be relevant if they are torched!

From TAoE 3 p1105
C.4 Resistor types
The usual choices for general-purpose use are metal-film
(axial-lead) or thick-film (surface-mount) parts. Thin-film
surface-mount resistors offer improved characteristics (ac-
curacy, stability, and ability to operate in cryogenic envi-
ronments). For power applications you usually use wire-
wound resistors, either in an air-cooled ceramic package or
a conduction-cooled (“Dale-type”) metal package. High-
value resistors (>10 MΩ, say) are usually of metal-oxide
construction (e.g., Ohmite “Mini-Mox” or “Super Mox,” or
Vishay RNX-series). Film resistors are not tolerant of high
peak power; for such applications use something like ce-
ramic or carbon composition, or other styles specified for
peak-power use. For the utmost in stability and low tem-
perature coefficient (tempco), you can’t beat the excellent
metal-foil types from Vishay. They exploit a clever design,
in which the positive tempco of the resistive metal element
(firmly attached to an insulating substrate) is cancelled by
the negative strain-induced tempco caused by differential
expansion of the substrate.3 We’ve listed some compara-
tive resistor properties in Table C.1; for much more detail
see §1x.2.