EEVblog #1256 - Most Gorgeous Test Gear Teardown Ever!

[EEVblog]

Probably the most gorgeous test gear teardown yet!
A master class in modular product design and design for servicing, a mystery retro bit of test gear from the bunker that was found in a dumpster.

[Deodand2014]

Most impressive. I hope you can find the full manual, sorting out the problem that resulted in it winding up in a dumpster may prove to be as interesting as the teardown.

[N2IXK]

That thing isn't simply an AC millivoltmeter. It is a selective level meter, also called a frequency selective voltmeter. It is essentially a laboratory-grade radio receiver with a huge input level range (microvolts to volts without overloading), and a hyper-accurately calibrated "S-meter". If you hook the input to a longwire antenna, you can use the speaker to listen to frequencies from VLF up through HF.  The major use of these was in telco central offices and the like, for checking various channels of carrier (FDM) systems. You can enter a specific frequency of interest, and measure the signal level at that specific frequency, while tuning out unwanted ones.  A very specialized bit of gear, but lots of fun to play around with.  I have an HP 3586C, which is similar in vintage, build quality, and functionality.

This thing is a DEFINITE candidate for a repair and play around video series. Almost certainly a linear PSU for low noise, so repairs should be simple.

Manuals available free online http://ftb.ko4bb.com/getsimple/index.php?id=manuals&dir=06_Misc_Test_Equipment/Wandel_and_Goltermann

[wn1fju]

I have the W&G SPM-19 Selective Level Meter and it really has no equal.  I find it to handle the AGC better and overall to be more accurate than my
HP 3586B unit. 

When I received mine, the power supply was blown up.  And I mean literally blown up - the big can electrolytics had spewed their oily insides all over
everything.  The stuff must have been caustic since it dissolved a lot of the wire insulation in the power supply.  I managed to fix it, but the fix didn't
last too long and I ultimately took the whole supply out and replaced it with a 120 watt Meanwell switching power supply.

It's fun to hook the thing up to my outside (ham) antenna and listen to broadcast AM at night.  Readable stations virtually every 10 kHz throughout the
entire band.  That's because the SPM-19 receive sensitivity is maintained across all frequencies, unlike my ham transceiver that has much poorer sensitivity in
the AM band than in HF.

[johnlsenchak]

I bet Shahriar Shahramian  over at   "The Signal  Path"   would  go totally nuts  if he got  his  hands  on  something like  that


You should do a video on those isolating  penetrator's  , that's something  that I never knew  existed  inside   electronic  equipment .

[vk6zgo]

Telecom Australia was a good customer for Wandell & Goltermann.

They used selective voltmeters to look at multiple channel landline carrier systems, as well as similar signals on microwave systems.
They also used similar units from Rohde & Schwarz, & some other companies, notably Siemens, with their "Pegelsender" & "Pegelmesser" test setup.

Interestingly, W&G & R&S, although competitors, entered into an agreement that guaranteed their equipment was compatible between the two companies, so special interfaces worked between both brands.

By the way, Dave, "Verstarker" (literally "strong maker") means "amplifier".

[Bud]

Just speechless...    

[szymon019]

Hi Colleagues,
Nice to see this topic. In the same time I decided to clean out dust and check electrolythic capacitors in my low frequency Vector Network Analysator SNA-2 (chaper equivalent to Bode 100 + Spectrum Analysator for DCDC converters, conducted emission etc.). It consist of two units analog section and upper controlling digital section. This construction is also pretty nice. I am going to make some photos and maybe copy EPROMs because they are getting the end of lifetime. This instrument can measre in range of 100Hz up to 180MHz and plotting Bode, Nyquist, Smith plots. It have GPIB interface and can controll HPGL plotter. It can still be usefull for analog circuit stability optimisation with external coupling transformer + HiZ fet probe. My unit is equipped with 50Ohm input / output.
I have idea to attach some modern MCU + SD card to store GPIB HPGL prints for exchange with standard PC.

Since I am going to check electrolythic capacitors condition old ROE and Siemens datasheets are welcome, also if somebody have SNA-2 documentation and could share with me would be nice.

[SparkyFX]

Very entertaining, but still informative 

[daqq]

Beautiful build quality... the amount of engineering must have been amazing.

Using today's state of the art tech, would it be possible to make such a device, only weighing far less, with much less shielding? Or is there simply no other way around noise at such low levels than to use a ton of shielding?

[BrianHG]

Beautiful build quality... the amount of engineering must have been amazing.

Using today's state of the art tech, would it be possible to make such a device, only weighing far less, with much less shielding? Or is there simply no other way around noise at such low levels than to use a ton of shielding?

Except for pre-stage amplifiers and a low pass filter, today for 20hz to 25Mhz range, we would just use a 16-20 bit 100Mhz-200Mhz ADC, then everything else would be 100% software.

[EEVblog]

FYI, someone on youtube comments said it was released in 1980 and cost US$45k in today's dollars

[thinkfat]

Some translations, Dave did a good job already with these, but maybe I can fill in some blanks.

Ordered by assembly group number (which is not unique for some reason).

1, 6V Gleichrichter -> "6V rectifier"
2, Eingang 75 Ohm -> "Input 75 Ohms"
3, Vorteiler -> "pre divider"
4, Nachteiler -> "post divider"
4, Vorverstärker -> "preamplifier"
5, 25MHz Tiefpass Entzerrer -> "25MHz low-pass equalizer"
6, Umsetzer HF/40MHz -> "converter/mixer HF/40MHz"
7, 40MHz Quarzbandpass -> "40 MHz crystal band pass filter"
8, Umsetzer 40MHz/10kHz -> "converter/mixer 40MHz/10kHz"
10, Eichmischer -> "calibration mixer"
11, Trennstufe" -> "isolation amplifier"
12, 10Mhz Übertrager -> "10 MHz coupler"
12, 40,01MHz VCO -> "40.01 MHz VCO"
12, 40,01MHz PLL -> "40.01 MHz PLL"
12, Vervielfacher -> "Multiplier"
13, Breitbanddetektor -> "wideband detector"
15, ZF-Verstärker -> "IF Amplifier"
16, Gleichrichter -> "Rectifier" or "Detector"
17, Demodulator -> "Demodulator"
26, 10 MHz Eing. u. Mitlaufs. -> "10 MHz input and tracking transmitter"
25, 10kHz Bandpass/25Hz -> "10kHz band pass / 25Hz bandwidth"
27, Phasenjitterschaltung -> "phase jitter circuit"

51, Rastphasenmesser -> "locking phase discriminator"
52, Rastoszillator -> "locking oscillator"
55, TTL-Stufe -> "TTL stage", "TTL converter"
56, Trägerphasenmesser -> "carrier phase discriminator"
57, Trägeroszillator -> "carrier oscillator"
60, Interpol. Phasem -> "interpolation phase discriminator"
63, Normalfrequenzteiler -> "reference frequency divider"
63, 10 MHz Trennstufe -> "10 MHz isolation amplifier"
64, 10 MHz-Oszillator -> "10 MHz oscillator"
65, Normalfrequenzoszillator -> "reference frequency oscillator"

[schmitt trigger]

Impressive beyond belief!

Having being personally involved in electronics assembly for most of my professional life I was wondering:
How did they build this thing?
What did the test and alignment procedure looked like?
How many details would have to be included in dozens of assembly drawings?
The bill of materials?

And I concluded something:
This must have been assembled by nude blonde virgins, working in secluded cottages deep in the woods of the Schwarzwald, assisted by elves while singing Gregorian chants.
Or something similar.

[WattSekunde]

Nice product overview from 1947-1998 about the test and measurement equipment "elektronische Messgeräte" from Wandel & Goltermann. The text is only in german but the pictures... 

https://www.wg-foundation.de/fileadmin/templates/pdf/Fert_Prog.pdf
PSM-19 is on page 11. The price tag on page 4 says: 34.650 DM. I would agree around 45k$ today.

Source:https://www.wg-foundation.de/index.php?id=1

[SilverSolder]

Would a lot of this fine instrument have been laid out by hand, back in the day?

In any case, an impressive expression of the science and art of electronics!

[German_EE]

Looking for those high resolution teardown photographs, anybody know the link?

[tszaboo]

Very impressive, lot of engineering.

Imagine the teamwork in this modular design. Maybe a dozen EE was involved in designing and laying out each board. Every board with clear specification and requirements. Every board individually had their performance benchmarked, characterized and documented. Imagine you have to go back and make your board just a little bit better, an extra 2dB noise floor. Tens of thousands Deutsche Mark worth of testing equipment lying in the lab.
1600 Employees in 1998.

Now  I want to go here and see this:
https://www.wg-museum.de/das-museum/

[PA0PBZ]

I got one in working condition! Very nice to receive VLF communication. Also, I wonder why the manual in the drawer says SPM-16?

[SparkyFX]

Looking for those high resolution teardown photographs, anybody know the link?

Daves flickr account

[chronos42]

Several years ago, I have made a repair report about a W&G NFA-1 audio analyzer for Ralf Ohmbergers Website amplifier.cd.
(https://www.amplifier.cd/Test_Equipment/other/NFA-1/Teil1/NFA-1_Teil1.html) Only in German language, I also did not open the cans to take photos, but you can recognize the typical W&G design. Same sort of construction like all W&G instruments from the 80th and early 90th. I got it defective from eBay for 300 Euro. At this time, I did not know much about Wandel & Golterman. It blowed my mind when I saw the unit from inside the first time. I have never seen something like this before. I have repaired this wonderful piece of measurement gear and I am still using it when doing some audio stuff.
Althought the NFA-1 is a very complex design the repair was not too hard because of the modular design, the very good documentation and the firmware with lots of internal selftest functions.
The NFA-1 uses 4 processor boards with Intel 8085 and 8086 CPUs, two of them are also fitted with an AMD 9511 math coprocessor. There was a defective 74HC27 at one of the processor boards. After replacing this chip the NFA-1 came back to life. I also had to do some re-capping in the power supply and had to replace the old and leaking  Ni-cd backup-accus, that was all. The unit is still working 10 years after repair without any problems.

[Fungus]

C'mon Dave, we gotta see inside that power supply!

I can't believe it's that difficult to access in a design like that. 

[schmitt trigger]

I second your motion!
We need a part 2 for this product’s video.

Your insightful comments  on the individual components would also be interesting.

[Dundarave]

I noticed what appeared to be something that looks like a bodge in this otherwise flawlessly built instrument...  Any ideas what these "flying leads" might be doing?  Their orientation looks a bit "undisciplined" and possibly in danger of shorting out some other parts, but it might be just the depth of field playing tricks...  I thought it most unusual considering the care and attention given to the design and build.

[BrianHG]

I noticed what appeared to be something that looks like a bodge in this otherwise flawlessly built instrument...  Any ideas what these "flying leads" might be doing?  Their orientation looks a bit "undisciplined" and possibly in danger of shorting out some other parts, but it might be just the depth of field playing tricks...  I thought it most unusual considering the care and attention given to the design and build.

(Attachment Link)

Adjustable sub-picofarad and inductive filter for the 2 germanium mixing diodes tied to the adjacent balun transformers.
You adjust them by bending them closer and further apart.  I've also seen this trick in old FM radio tuners where 2 shielded wire, around the type of network cable, are twisted together, but, the top is cut with no connection anywhere.  The filter/mixer is tuned by the number of twists (around 2-4 twists, sometimes 2 or 3 wires together depending on design).  In the case of this unit, it is tuned to an unbelievable super sharp edge as the 2 wires are just spaced apart floating in mid air.  Altering the bend of those 2 wires would alter the characteristics of that transformer-diode mixing/detector filter.