The decline of Soviet calculator quality


Five year ago I bought a brand new Soviet Elektronika MK-61 RPN calculator, that was made in June 1992. The calculator came complete with AC adapter, manual and slipcase in its original box, and it was clear that it had never been used. The keyboard on this calculator is simply awful with no click or feedback of any kind, no travel to the buttons and constant repeating of entries.

At the time I thought that this was simply the design of this model, until recently I came across a second MK-61 made earlier in October, 1989. This calculator is physically indistinguishable from the first unit and was made in the same Kwasar factory, however, the keyboard is totally different with a distinctive click and feedback as well as noticeable travel to the buttons. It also has virtually no repeating. This calculator is very definitely used with scratches and chipped case plastic, yet the keyboard still works perfectly. I also bought a MK-54 made in May, 1984 in the Kwasar factory, which uses the same case, display and keyboard as the later MK-61. It too has a nice clicky keyboard like the earlier MK-61.

So it seems that just as the old Soviet Union was beginning to collapse, so was the quality declining in its consumer products like its calculators. Perhaps they were trying economize by cheapening their keyboards in a vain attempt to become profitable capitalists.


I don't know if this applies in your case, but with my MK-61's, I noticed that every time the keyboard feel was bad (specifically, little key travel) it was due to the small sponge layer between the keys and the switches being "corroded". And for some reason, the degree of deterioration of the foam doesn't seem related to the actual amount of usage it has seen: maybe it has to do with the kind of material they used case by case, or maybe the storage environment in these 20 years matters - maybe some storage conditions deteriorated your "brand new" calculator faster than the other...


That makes sense - the key technology they're using, it seems, is a metalized mylar snap dome for tactility, and a foam sheet for springiness (I think, anyway).

If that foam sheet has degraded, the mylar dome may be partially collapsed under the weight of the key, and there'll be no travel whatsoever. And, when it IS a case of the foam sheet being collapsed, turning the calculator upside down should reveal that quite easily, and tactile feel may even return when it's upside down. (If the mylar domes are degraded, though, then that may not work.)

My MK-61 was made in 1991, and feels fine. Not GOOD per se, but it works reliably and it feels better than, say, most TI calculators.


I tried turning the calculator upside down and there is a very small amount of travel but absolutely no tactile feedback or click when the buttons are depressed.

Edited: 31 May 2013, 2:47 p.m.


Just for the record; my 54 from 1985 is slightly clicky and better than my 61 from 1991 which is mushy and more prone to doubling entries.


I had a MK-52 whose keys felt like you described your more recent MK-61, except for the bouncing. Actually, I was amazed how reliably this calculator registered, well, just *touching* the keys. There was no noticeable travel at all.

The EEPROM storage was a great and unique concept. Unfortunately, the EEPROM chip in my sample was dead, so I gave it away to someone wanting it as it was.

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