EEVblog #634 - Analog Multimeter Teardowns

[Bored@Work]

That Unigor meter to my knowledge had at least two different version/manufacturer. One is made by Metrawatt and the other is by Ganz. I dont know who copied who but aside from the case of the meter, the inside of the two was very different (2 board construction to 4).

I wouldn't say they are so different. More like a different model from one product line or an earlier model. E.g. the nicely straightened and bend wires inside, the protection switch, the warranty sticker with the blue border, the technique with the wires for connections between boards are just a few of the similarities.

And after thinking about it, I remembered something. We previously had a case where we found that a eastern European company (Iskra) was building meters for Metrawatt, from the Unimer series.

Maybe Metrawatt also hired Ganz to build multimeters for them.

https://www.eevblog.com/forum/reviews/old-iskra-unimer-2-%29-%28metrawatt-clone%29/

[quarros]

I wouldn't say they are so different. More like a different model from one product line or an earlier model. E.g. the nicely straightened and bend wires inside, the protection switch, the warranty sticker with the blue border, the technique with the wires for connections between boards are just a few of the similarities.

And after thinking about it, I remembered something. We previously had a case where we found that a eastern European company (Iskra) was building meters for Metrawatt, from the Unimer series.

Maybe Metrawatt also hired Ganz to build multimeters for them.

https://www.eevblog.com/forum/reviews/old-iskra-unimer-2-%29-%28metrawatt-clone%29/

That could certainly be the case. One of my friends told me that most of these types of multimeter's  (ones with similar case's) are a copy of the Ganzuniv. But I was unsure if I could believe that.

[128er]

Here are a few pictures of my only analog multimeter.

-Measures up to 100A AC/DC and 1000V AC/DC. 5 kOhm/V.

-Resistance measurements up to 10 kOhms.

-Accuracy is +/- 1,5% for AC/DC ranges and +/- 2,5% for resistance (full scale deflection).

The HRC fuse was replaced with a wire when i got it and it is still    .  The opamp is a LM4250. It is presumably built in the late 70s to early 80s. Weighs about 1 kg.

Manual (only in german, but with scematic):
http://www.directupload.net/file/d/3176/v7wddy63_pdf.htm

[balu]

Hi Dave,
Thanks for the great teardown of good old analog Multimeter. I have an old Multimeter C-4317 (?-4317, Manufacturer: Mashpriborintorg ) from USSR. It works absolutely fine today and is assembled August, 1977.

I’m not sure, but I think the design of the UNIGOR A43 is made by HFG Ulm (Ulm School of Design in Germany 1946...1953, follower of the Bauhaus 1909...1933).

http://en.wikipedia.org/wiki/Ulm_School_of_Design
http://en.wikipedia.org/wiki/Bauhaus
http://www.hfg-ulm.de

Pictures of the C-4317 Multimeter:

[josko]

My favorite is Czechoslovak Avomet II DU10 made by Metra Blansko, it's been in production from 1953 until at least late 70's.
Really rugged meter (heavy bakelite case) and fine movement.

The interesting think that there is not single range switch, but three separate for Volts, Amps and Ohms and you can select range switch by pushing it down, really neat, I've never seen this kind of construction elsewhere.

Of course being 50's vintage it's all point to point construction...

Pictures:



Details: http://www.radiohistoria.sk/Oldradio/main.nsf/wcatalid/0006065

[Flump]

great video dave
i took apart one of my analog meters while watching it!

I think I have about 11 analog ones now but this one is
more similar to the unigor than the others are

[BobC]

Please keep reminding us to do the "Thumbs Up".  When you say it, I do it!

[denelec]

Here's a quick teardown of my 30 years old Micronta 22-204C from Radio-Shack.
It's a 50 000 ohms/V meter.
The rated accuracy is 3% on DC and resistance and 4% on AC.
It's made of very brittle plastic.æ

[denelec]

Sorry, somehow, the pictures didn't follow...
This meter WASN'T made for an industrial environment.

[Stonent]

Sorry, somehow, the pictures didn't follow...
This meter WASN'T made for an industrial environment.

Yeah that's my meter except yours is in much better condition, for example, yours still has unburned resistors and the metal part that gives you an indication of what range your knob is set.

[linux-works]

I loved that micronta radio shack meter with the range doubler.  it was my first new meter and I built mine as a kit.  lasted a long time but the case wasn't very strong and it started to crack, over time.

but it was affordable and great for a teenager, just starting out   I think I got mine in the late 70's.

[calin]

I have to Troiplett 630 , one exactly as dave's and one same but no 6KV .. got them few months ago of the bay for ... 12$ both. It was literally an stumble upon buy case .. They are both spot on, batteries still good etc. Owned before one by Raytheon and one by Hughes Aerospace .. yeah that Huges . Indeed these Triplett meters are a piece of art ... not to mention that they still work good, I still use them from time to time. The one that can do 6KW came in pretty handy when I worked on restoring an old Tek 475 .. which unfortunately still waiting for a CRT.


I left the cal sticker  on the Hughes one just for historical reasons


Now here is my 2 cents question. I just bought a  HP 6112A PSU made in the 60-es , and the PCB plus board layout are awesome (2 sided through hole design) neat and clean. Now .. why the hell thse meters are all built so crusty compared to that .. they are from same era right ? 


I curious yes I got the PSU working ... some pictures here. https://www.eevblog.com/forum/testgear/harrison-high-stability-lab-psu-with-oven-stabilized-voltage-sense-hp-6102a/msg463854/#msg463854 

[petertux]

nice teardown Dave and also very nice pictures in this thread, keep them coming guys!

I thought I'd share pictures of my soviet TL-4M multimeter.
it can measure 0.1-1000V dc/ac, 0.3mA-3A, 100uA, 1-10kohm and transistor currents.

[zaoka]

Here is one of best Japanese analog meters of that time.  HIOKI M-230A

I did not take a picture of the protection relay at that time...

In catalog they said that this meter was exceeding Japanese military standards at that time. If I remember correctly it is 1.5% tolerance for DC.

[tekfan]

great video dave
i took apart one of my analog meters while watching it!

I think I have about 11 analog ones now but this one is
more similar to the unigor than the others are

Is that a Russian Z4300 series multimeter?

[zapta]

Analog multimeters bring a lot of memory. Got my first one in elementary school, it didn't last a day, I connected it to main voltage while in the wrong range, my dad took it to the local electrician but he did not know how to fix it.  My next one was a good quality 20kohm//V Sanwa that served me for years. At the time I was building digital phone dialers and the analog meter was very useful to count the dialing pulses. Later used big ones professionally, we used to call them 'avo' regardless of the manufacturer and model just like 'fridge'.

Not using or owning any now. Between a digital DMM and a DSO I have everything I need.

[rsjsouza]

The ICE Supertester 680R does that too. It's supplied with a 230V mains lead for capacitance measurment. Always made me kind of nervous...

I remember taking some shocks from one of the leads of my dad's 680R when trying to measure capacitance, frequency or the ohms x 10000 range... not fun.

[Chryseus]

Here's a Japanese made TMK 700 I pick up a little while ago off ebay.
Gotta really love the build quality in these old meters

[david77]

If you're really into old and very old T&M gear have a look at this site

http://www.historische-messgeraete.de/index.php

Now there's somebody with a real fetish!

As far as I can tell it's only available in German but the pictures are good enough  .

[elliott]

I think I might have a good solution to the 30V battery for the Tripletts. An 18650 Li-Ion cell fits perfectly into the original battery holder. Plenty of room for a small DC-DC converter in these things too.

[david77]

Here's my oldest analog multimeter the Multavi 5, made by Hartmann & Braun sometime in the late 50ies. It used to belong to an old electrician who used it throughout his career but luckily always took good care of it.
It is one of the better instruments of its time with 1% fs accuracy in the DC ranges. You can also connect it to measure volts and amps at the same time making power calculations easy using only one meter.

The last picture shows my oldest piece of T&M gear, a Siemens & Halske amp meter, it does 0,1/1/10ADC. It's got a date stamp inside showing it was built in 1943 and it's still pretty much spot on, this meter is really quite useful and of all my analog meters I use it the most.

[Tothwolf]

If the label on the Unigor doesn't say BBC Metrawatt, but just Metrawatt, then that particular meter must be from before 1968. In 1968 BBC bought Metrawatt and they became BBC Metrawatt.

That also matches the age of other Unigor meters, the Unigor design series originated in the early 1960th.

So you are looking at a 45+ year old meter, still in spec. and where they did manage to get the pin spacing right - as opposite to that second meter 

Based on the package type of those two diodes I was thinking early to mid 1960s, too. Tag strips and other point to point construction designs would have still been common construction techniques when this meter was made, so the use of pc boards would have still been seen as novel and more "cutting edge" for a multimeter.

I have an earlier Simpson 260 (I think either series 3 or series 4) that seems to date from around the same time period as the Metrawatt, and it's pc board seems just as "crusty" in design. It looks similar to these: http://simpson260.com/260-3/simpson_260-3.htm http://simpson260.com/260-4/simpson_260-4.htm

Dave, is there a date printed anywhere visible in the Metrawatt meter?

[MatthiasBerlin]

It seems that it's still possible to buy slightly updated multimeters of the Unigor series from that company Ganz in Hungary mentioned before:
http://www.ganzinst.hu/wp-content/uploads/2013/05/Ganzuniv.pdf
These similarities simply cannot be pure chance...

Maybe they'd like to send Dave an up-to-date version for a teardown?

[Steffen]

I remember, 2008 during my vocacional trainig (I was 19) I also was suggested to use an old Simpson brand analog multimeter for repair jobs. It was quite easy to find defective transistors inside an old 6,5V 80A linear power supply (Rack mount 2U). That device contained not less than 15 2N3055 all mounted in parallel with balancing resistors. It was a heavy device with many faults. I replaced about 4 transistors, but could not proceed to test, because that repair shop did not have a dummy load to test this device under maximum load. In the cabinets, we also have some Multavi 5, but they are not used anymore, even if they still work.
The most impressing battery life i've ever seen was inside an old Rode & Schwarz URV. That device was maybe 30 or more years old, but the battery was still nearly full. With growing frequencies and more modern digital power meters, the URV has also become obsolete.

[G7PSK]

I took some photographs of my AVO 7 Panclimatic. It is supposed to be usable in the tropics, its ex RAF. so I suppose they need to be able to operate in all parts of the world. The meter is sealed with an O ring between the metal back and the Bakelite front and the battery box which comes out with the back unit connection being by 3 brass springs.1% on DC and 2.25% AC also has capacity using 50 HZ mains at 100 to 250 volts it also measures up to 40 M ohm using up to 900 volts DC or AC.