Question: How Do I Clean My Vintage ISKRA 111M?

[Wolfcraft999]

I recently acquired this vintage calculator, and i was wondering how to clean off this thin white crust that seems to be covering every surface inside. It does not come off when I try to scrub it.

Here are some pictures:


As you can see, there is a thin coat of it everywhere.

Does anyone have any suggestions?

 

[Fringe Reception]

:welcome: Wolfcraft

Are those Pixie Tubes used for the display? It certainly is an oldie circa 1970 (?). Is the coating electrically conductive? If not, I'd leave it alone. My concern is it may indicate electrolytic capacitors have failed and the electrolyte (acid) has leaked (even vapor) and slightly etched all of the surfaces. Before turning it on, I would definately replace all electrolytics.

Although it would take a long time, you might try removing it with pencil erasers. Specialty erasers with different abrasive qualities are available through artist supply companies or mechanical drawing (drafting) suppliers (if any are still in business, these days). They are available as blocks or tubular, like a pencil.

Let us know how it comes out and thanks for the photos.

Jim

 

[Wolfcraft999]

Thanks!

Yes, they are Nixie Tubes. And thanks for the suggestion! I'll check it now for any leaking electrolytic capacitors.

*10 Minutes Later*

Ok, I've checked and tested every single one of them, and none are leaking. And one more thing to note: The white coating is only on metal surfaces that are grounded. So may be it has something to do with that?

And here is some info on the calculator: http://www.olek.waw.pl/kalkulator-iskra-111/ . . . Oh, it's in Russian . . . Oh well.

 

[Fringe Reception]

Wolf,

I don't know how you could have tested the capacitors, unless you unsoldered one end of each of them. Secondly, even if they appear to be good when tested with an ohm meter, it does not guarantee that they will won't internally short-circuit at operating voltage.

Here is a great resource website to find wiring diagrams and owners manuals. I didn't see your unit shown there, but you can request information from their contributors. Good luck!

Jim

mods.dk -> Instruction, users and service manuals for

 

[MrPogi]

About the white deposits - do they have a pattern? My thought is that it may be smoke residue. I've seen many boards with wavy or wispy white deposits that are the result of smoke or fire.

 

[Wolfcraft999]

No, they are just a solid, slightly cracked white residue with no smell of anything. I don't really know what it could possibly be. It looks like some sort of calcium deposits, but it won't come off no matter how much I try.

 

[Wolfcraft999]

Good point, I'll keep that in mind. I need a 110v to 220v converter anyways, so I would not be able to turn it on in the first place.

I'll ask for some info on the 111m on that website, thanks!

 

[Wolfcraft999]

I was wondering also, what is the best method to clean those yellowed keys? Because I don't wan't to damage the black plastic that was molded into it as shown here:

 

[Wolfcraft999]

Recent discovery! I have been trying to fix it for some time now, and I have managed to make the 7's work. And that's it. No other keys are responding at all. Here is a video to show you what it does: [video=youtube;U1OUTUf5oZw]https://www.youtube.com/watch?v=U1OUTUf5oZw&feature=youtu.be[/video]

 

[Fringe Reception]

First, try soaking the "keys" for at least two days in water plus Dawn dishwashing liquid (at room temperature) and brush them from time to time with a soft toothbrush. Do not run them through your dish washer as the far higher heat may distort them. They may not return to white but their surfaces will be clean.

Next, I would (personally) try Windex, which contains a small percentage of ammonia and test on the side of one key/button to see if there is an adverse chemical reaction.

Beyond that, I'd leave the cleaned keys alone.

Jim

 

[Wolfcraft999]

Ok, I'll try that and report back after I have finished this process.