Rate my 42 years old 2200uF/25V electrolitic capacitor

[RoGeorge]

The capacitor was produced by IPRS Baneasa, a former manufacturing plant from Romania.  The marking says 2182 (week 21 of year 1982), so 42+ years old, nominal 2200uF/25V.  Bought from a brick and mortar electronics shop in Bucharest (the Internet was not yet a thing).  Don't recall the price.

... 42 years later ...



(The measuring wires alone when in short show 0.27ohms, so the capacitor's ESR is 0.12 ohms)

[Bryn]

Well, you've kept it in good nick I must say so... full marks 👍

And on an unrelated note, my mother first got her electric knife in that year (and was an engagement gift, just to say), and is still in good condition also

[dietert1]

The bigger ones usually last longer. I'd guess for a well made capacitor without faults endurance is proportional to volume divided by gasket rim length. And of course it depends on temperature. The pressure difference that drives diffusion will be small near ambient temperature.

Regards, Dieter

[MT]

https://ro.wikipedia.org/wiki/IPRS

[coppercone2]

It was established by the Decision of the Council of Ministers no. 438/1962 by which it was specified that the object of activity is "the manufacture of passive electronic components and semiconductors". It was a state enterprise of republican importance belonging to the MICM (Ministry of Industry and Machinery Construction), which later became MIMUEE, being subordinated to the CIETC (Central of Electronic Industry and Computing Techniques). [ 1 ]

The first production workshops were organized in the premises of the "mother" Electronica plant in 82 Baicului str., on the second floor of building 20, on an area of ​​approximately 4,000 square meters. Low and medium frequency transistors , diodes , styroflex capacitors and miniature electrolytic capacitors were manufactured here for the first time in the country . [ 1 ]

Sections are presented in ascending order of name, the year of establishment is listed separately.

    Section 2200 – Low Power and Low Frequency Germanium Devices – Year Established: 1962;
    Section 2300 – Silicon diodes and thyristors – year of establishment: 1969;
    Section 2400 – Integrated Circuits – year established: 1970;
    Section 2500 – Low Power Silicon Transistors and Diodes – Established: 1974;
    Section 2700 – Passive components – year established: 1962;




In 2003, Elmefa BV - a Dutch holding specialized in electrical and electronic production - tried unsuccessfully to buy IPRS Baneasa from APAPS but was eliminated from privatization [ 6 ] . In September 2003 , the majority stake of 51.4% of shares was bought from AVAS (formerly APAPS) by Ogharit Trading CO Syria , controlled by businessman Omar Hayssam [ 7 ] . Ogharit Trading came with an offer of 3.1 million euros which included the payment of the company's debts [ 8 ] . But, after that, the Romanian state wrote off almost all of IPRS's debt, so that in reality Ogharit Trading bought the company for the sum of 140,000 euros [ 8 ] . After taking over the company, the Syrians did not make any investment [ 8 ] . At one point there was talk only of trucks leaving the enterprise loaded with "scrap metal" [ 8 ] . The Syrian company was engaged in the import-export of general goods and construction, not having as its main activity the field of information technology [ 7 ] . Also, the company was founded in 2001, so even if it had this object of activity, it would not have met another pre-qualification criterion established by APAPS, namely five years of experience in the field of information and communication technology [ 7 ] . However, only after the conviction of Omar Hayssam for acts of terrorism in the case of the kidnapping of Romanian journalists in Iraq , the Romanian authorities realized that the Ogharit Trading company did not have the necessary quality of a strategic investor [ 7 ] . The authorities canceled the privatization contract and announced that they will try to maintain the company's object of activity [ 3 ] . By December 2006, AVAS sold 1.4 hectares of the company's land to the Lebanese Jabra family [ 3 ] . On June 15, 2007, the Bucharest Court decided to cancel the sale-purchase contract of the majority stake to Ogharit Trading [ 7 ] .



quite a interesting history there

what is going on there now? you can write a opera about it

[T3sl4co1l]

40 years isn't wild, especially if it's spent much of that time on the shelf

I have a pair of 2.5mF 350V computer grade caps on my bench at the moment, which I recently reformed to 390V (a bit above rating for good measure).  Date code "7816", they were removed from a ~5HP motor drive (SCR based!) that probably last ran in early/mid 2000s.

They're visible on the side of this shot, in fact:



I didn't measure the ESR of them as part of testing, but they're certainly low enough; one line of evidence says under 0.2Ω.  C within tolerance.

I forget what all I have around here that might be older; tube era equipment certainly, though those will have higher ESR too.  I got rid of a whole box full of metal-can (tube era, and voltage) caps a bunch of years ago, as I was never going to use them for anything, but there was probably some 50s and 60s stuff in there, maybe even older.  With reforming, most of those come up just fine.

The oldest capacitors I had, that I know failed, would be the (mostly metal-can) caps in the Tek 475 I started out with; they dried up after a solid, probably, 5 or 10 years of use?  Dated 1973 so they had a good run, to be sure.

Tim

[RoGeorge]

This one didn't see much use either.  A couple of years, at most, during the 80s.  Then it stayed mostly unused.  It was used to filter the mains ripple after a bridge of diodes (capacitor seen in the upper right corner), in an adjustable 0-12V/1A voltage regulator with no less than 4 transistors! 



The TO-3 is a germanium ASZ15.

[wraper]

Capacitance going up is not a good sign. It means oxide layer is thinning out and need of reforming.

[SiliconWizard]

Yes, actually long-term shelf storage (so without any voltage applied) inevitably results in the oxide layer thinning and it will never get back to its nominal state when finally voltage is re-applied.
You could measure the leakage current (which I'm not sure your tool allows to) and should also note a much increased value compared to nominal.

So don't get too "excited", this 40-yr old capacitor is probably not in as good shape as you think it is.

[Smokey]

4 out of 5.  Would capacitate.

[RoGeorge]

Yes, actually long-term shelf storage (so without any voltage applied) inevitably results in the oxide layer thinning and it will never get back to its nominal state when finally voltage is re-applied.
You could measure the leakage current (which I'm not sure your tool allows to) and should also note a much increased value compared to nominal.

So don't get too "excited", this 40-yr old capacitor is probably not in as good shape as you think it is.

Wanna bet?!  Challenge accepted! 

After about 15 minutes at 25V from a Rigol DP832 power supply, the measured series current (leakage at room temperature, now 27*C, or 80*F) dropped to less than 15uA, and still decreasing very, very slow.  Will let it at 25V for an hour or so.  By the time I've added the pics, the current is now 11.16uA, the nA digits fluctuates, sometimes showing less than 11uA.

Out of curiosity, at what voltage and for how long to keep it powered to consider the capacitor reformed?


At a closer look, the marking doesn't look like it would be manufactured by IPRS Baneasa.  It is marked with MM, probably made in some other eastern European country.  Anybody recognizes the manufacturer from the pics?

[T3sl4co1l]

I like to reform a little bit over rating, so that at operating voltage, leakage is nice and comfortably low.  That does depend on how close to ratings it's actually operated... usually you're reforming components of a piece, so the operating voltage is known.  Loose components, I guess you can just do whatever.

A few hours getting to uA sounds perfectly reasonable.  A large one might take mA (or 10s, or 100s..) for some hours, and get warm (but not hot, don't cook it!) in the process.

You could try raising voltage a bit, or heating it up (by external means, not due to leakage current, lol), and see if that has any impact on leakage at lower voltage and room temp.  Some uA, is most likely well within tolerance, so I don't expect much change or improvement at this point.

I had a need for a low-leakage tantalum cap some years ago, which I evaluated by wiring up a bunch of MIL spec parts (dry M39003 type) at rated voltage and temperature, and letting that simmer for a few days.  IIRC, initial leakage was singles, tens of uA? Final, varied around (above/below) 1uA or so..?  Hmm, wonder if I even wrote that down anywhere.  Not that MnO2 chemistry is at all the same, but... it sorta is, being an electrolyte nonetheless (just a solid-state one), though as I recall, it doesn't so much anodize the tantalum where leakage current flows (sneak paths, fractures, etc.), but transient heating reduces it to ~insulating Mn2O3, blocking off the site; a self-healing process.

For heater, I used a wirewound resistor.  Just snug all the caps inside a tubular resistor, power it up, and wrap with a towel, lol.

Tim

[RoGeorge]

This capacitor is about the size of a shotgun shell, don't have such big tubular resistors.  Please don't make me curious about temperature behavior, already overdoing this measuring thing. 

As for the normal charging, now, after almost 5 hours kept at its nominal 25V, at room temperature 27.6*C, the current is about 6.17uA, with the last two digits jumping around about +/-100nA.  The current still seems to be de decreasing.

After heating the capacitor be keeping it inside my fist for a minute or so, the current increased from 6uA to 9uA.

[RoGeorge]

7 hours later the current measures 5uA at 25V.

For a bigger voltage, at 27V the current is 24uA stationary, and at 29V the current settles at about 110uA but it is slowly increasing.  I didn't try 30V.

[bsw_m]

Here everything is visible in the photo

[SiliconWizard]

Nice Tesla BM595.

[dobsonr741]

The manufacturer is MM Mechanikai Művek from Hungary.

[RoGeorge]

While applying more than the 25V nominal voltage, the charging current was going down, then up, then down again. 

This made me curious about the current evolution, so made a Python script (.py) to automate the test.
- the power supply (Rigol DP832) is stepping the voltage from 0 to 32V, intentionally more than the 25V max voltage of the DUT (2200uF/25V)
- each voltage level is kept constant for 10 minutes, this DC voltage steps are applied to the DUT
- the charging current of the DUT capacitor is measured every 5 seconds with a DMM (Metrix mtx3283, 10nA resolution)
- measurements are timestamped and saved as CSV (.csv)
- the CSV values are plotted live using a gnuplot script (.gp)
- no heating observed, measured at room temperature (27.6*C, or 81.7*F)

(Side note for the attached zip - the .py script is calling a tool 'mtx3283_read' that reads the current value measured by the DMM over serial MODBUS.  For convenience, the 'mtx3283_read' was compiled to an executable.  The sources and the executable for the 'mtx3283_read' can be found at https://www.eevblog.com/forum/testgear/sniffing-the-metrix-mtx3283-dmm-modbus-protocol/msg3740053/#msg3740053)



One could tell the nominal voltage by watching the charging current while stepping up the voltage.  Might be useful to identify unmarked capacitors. 

I'm not sure about the meaning of those humps in the charging current seen during the last few voltage steps, or why they appear only at higher than nominal voltage.  Any clues?

[Gyro]

...
I'm not sure about the meaning of those humps in the charging current seen during the last few voltage steps, or why they appear only at higher than nominal voltage.  Any clues?

That looks like the voltage levels where the anode oxide starts to need re-forming to thicken it (i.e. you are seeing chemical electrolysis). If you had gone straight in at 32V you might have seen some destructive current flow or heating as the oxide punctured, I don't know. Old high voltage electrolytics have been known to fail catastrophically if hit with full HT without a period of re-forming.

[rsjsouza]

That is a very nice vintage capacitor. As Dieter mentioned above, the large capacitors seem to last much longer through the passage of time. Also, axial models seem to last much longer than the radial ones.

I have a few very old capacitors, including the one below which is still in excellent shape. This photo was taken about 2h after the more recent power up.