Anyone scrapped these old telex?

[orvi]

I personally saw silver and rhodium ones. And heard about PGM/silver alloy, mainly PdAg.

 

[Slochteren]

OK will put 10 in nitric these evening and see what happens..

 

[Slochteren]

These pcb's are in them, single sided gold fingers on the onthere side then the components. Don't see much interesting. 1 tantalum and some metal cap transistors and the eproms wich have the gold paste. And some Dil ic's wich are, in my opinion, not worth the effort.

 

[Slochteren]

And the backplane connectors, in these colored condensator is there any PM and that other part on the picture?

 

[AMS-Pro]

True - however those reeds will more often then not be plated on the "contact end" with a PGM plating - PGM/silver alloy plating or even gold plating

Kurt

Yeah, that could be, I assume you mean contact end to the board. I have had mixed results with components like these. I think part of the issue with mixed results with these kind of components may have been where the glass is formed around the ferrous reed, it acts like a coating where it touches, and entraps what could be there. But' I would be to interested in seeing the results of some kind of testing, I hope Slochteren is successful in recovering something.

 

[AMS-Pro]

These pcb's are in them, single sided gold fingers on the onthere side then the components. Don't see much interesting. 1 tantalum and some metal cap transistors and the eproms wich have the gold paste. And some Dil ic's wich are, in my opinion, not worth the effort.

I would pull the red switch too. You could check the blue as well internally. Cool looking PCB, I'm liking the eproms, thank you for the pictures.

 

[AMS-Pro]

OK, also the coating on the tips? Never saw Iron nickel as contact surface, but that doesn't mean it doesn't exists... Just wishful thinking

With what Kurtak is saying, it could be on the tips (contact end). I just got off the phone with a contact I have in the industry, what I'm allowed to tell you is that they manufacture them with gold, or ruthenium as the plating surface for the contact points (edits* inside the case/glass). I hope that helps, this may not be the case with all of them that are produced by other companies, but it is with my contact.

 

[Alondro]

True - however those reeds will more often then not be plated on the "contact end" with a PGM plating - PGM/silver alloy plating or even gold plating

Kurt

I also look inside test switches on the boards. Mostly, those have silver-plated bits on the inside, but sometimes, especially for high-end machines, it's gold-plated. Got a bunch like that from boards used for industrial equipment.

 

[Slochteren]

I put 12 contacts in 53% nitric, cold 10c nothing happened after 1 night, did put them on low heat. The color turned green and the contact tips remained as foils. Did a stannous test on the liquid, added a video and foto off the stannous test, and a picture off the green liquid. Tested also with dmg without any color change. What would be the next step to determine the type of metal of the contacts.

 

[AMS-Pro]

Well, since ruthenium is immune to nitric acid, and hydrochloric acid, doesn't dissolve, you could take one of those foils and put it in a small beaker. Thoroughly neutralize any nitric acid on or in it with calcium carbonate, and rinse with distilled water, do this until you are sure no nitric acid is remaining on the foil at all. Remove foil to dry, and clean the beaker. Fill small beaker with bleach 50ml-100ml place beaker under your fume hood, and turn the fume hood on. Drop the single foil into the bleach. If the foil starts dissolving, and reacting it could be ruthenium. The yellow you would see coming off of it is ruthenate, and perruthenate ions. The bubbles you would see coming off of it will be a mixture of Ruthenium Tetroxide (an extremely toxic gas), and oxygen. If you decide to do this, please be safe and cautious. If it ends up being that, I would just leave the rest of it alone. Ruthenium is dangerous to recover, Ruthenium Tetroxide is not only extremely toxic, it is also explosive. In small scale it's not worth recovering, way to much risk, not enough reward, and should be avoided.

 

[Slochteren]

thanks for the suggestion, I did some reading this evening about Ruthenium, didn't read anything about the use in contacts, I hope it is something else. Have to consider the testing procedure you mentioned..

 

[orvi]

Stannous will tell you only if some values dissolved into solution. And as you have untouched foils, it is not Ag. And it is something more noble. It could be also platinum (but i never experienced platinum coated contacts), rhodium or as AMS-Pro said ruthenium (also never have/heard of ruthenium plated contacts).
Next i will consider take one foil, put it in the test tube, drop few drops of HCl and few drops of nitric. Heat.
If it dissolve, it is probably platinum. Ruthenium is insoluble in AR. Rhodium will probably dissolve to some extent, but it would be slow.
If it dissolve and colour the solution (Pt and Rh produce yellow-orange and reddish coloured solutions, respectively), test with stannous. Testing for Rh with stannous is somewhat more complicated, but you can find it here on forum

 

[orvi]

And the backplane connectors, in these colored condensator is there any PM and that other part on the picture

Snap one with pliers. If it is ceramic inside, it could be MLCC, if there is rolled Al/plastic foil, trash.

Nice score with EPROMs, not something extraordinarily yielding, but you have quite a bit of them also easy to process, clean work as practically no base metals are present.

Also, red "multi-miniswitch" and blue switches will be good for recovery. Some tantalum (various types in the boards), but it should be checked. Electrolytic caps and tantalums are often very similar looking, but tantalums are heavier. And you can also cut one open to see.

Black DIP ICs... depends. You said you have 20 pieces of this machines, so in the end, quite a pile of them. I usually chceck the insides. Some types have gold plated insides of the legs and surface under the silicon die. Yield is low, but with that volume it adds up. You must decide what is worth your time

Also cut the top of some transistors to see if there is gold bonding wire and gold braze inside.

 

[AMS-Pro]

thanks for the suggestion, I did some reading this evening about Ruthenium, didn't read anything about the use in contacts, I hope it is something else. Have to consider the testing procedure you mentioned..

You're welcome. I wasn't aware of its use in contact points either until I was on the phone with that contact of mine. It was an interesting bit of tidbit to learn. I even verified it was that, and not Rhodium, when I heard it, because of hearing it. As soon as I heard Ruthenium, I was thinking oh no, not good as far as this discussion of recovering it is concerned.

 

[Slochteren]

Ok i will take a few foils and put them in AR, sounds saver then the mentioned ruthenium test..

 

[Slochteren]

They dissolve in AR, color of solution see picture, stannous test I would say dark red..

 

[AMS-Pro]

Ok i will take a few foils and put them in AR, sounds saver then the mentioned ruthenium test..

The Ruthenium test was only there if they hadn't dissolved in anything else.

They dissolve in AR, color of solution see picture, stannous test I would say dark red..

Which they did, so that is wonderful that you don't have to deal with that.
Your spot test kind of looks like it is showing for gold, but I'm also not seeing the dark red you're talking about so it could be my screen. you can dilute the spot sample 5x-10x and it should get more of a lighter purple if it's gold. You can also use filter paper, or a q-tip for a different visual.

 

[orvi]

Dark red stannous... Platinum used to be orange to brown colour. But colour of the AR solution is similar to very dilute Pt.
Could be also alloy of metals used to braze the contact. Spot test on the photo does not look red to me, but this could be due to the photo. It look like some gold could be resent, but just guessing.

 

[Slochteren]

Just checked the stannous by daylight and looks more like gold, also the stannous test from yesterday looks like normal gold test after 1 day. Will pull 100 contacts an threat it as gold, see what happens after adding SMB. Still wondering where the silver color comes from.

 

[kurtak]

. Still wondering where the silver color comes from.

One reason could be if the plating is a gold/PGM alloy

PGMs are a bleaching agent when alloyed with gold (or copper) thereby literally bleaching the color (yellow or red) out of the gold (or copper) making it white (silver)

It takes very little PGMs to bleach gold/copper which is why they use PGMs to make white gold

Nickle is also a bleaching agent for making white gold/copper alloys

Kurt