Surprise gold in hard drives.

[Bellien]

Hello,

I was gutting some hard drives to salvage bearings and magnets and in a mid 90's era drive found that the wires to the recording head were gold, not copper. I had already stripped the manufacturing data off the drive and have no idea who made it or what it's capacity was. I'm not positive but it looks like some of the circuitry which was connected to the head (inside the drive) is gold as well. I've stripped a handful of drives from the same rough time period, but have never noticed any gold, or gold colored wires in them.


I also got my hands on a very old 1980's hard drive(as in I dug it out of a garbage can). The manufacturing data had already been striped off , and the drive was somewhat banged up. I got the bearings out and was giving it a last look over when I noticed that it had two sets of DIP switches and both had looked like they had gold plated pins. I popped the end of one of them open and found that the switch contacts appeared to be gold plated as well. When I dug into one of them with a knife point to check, I found that the metal was the same color all the way through and about as hard as lightly annealed copper. It appears that the metallic components in these particular DIP switches may in fact be solid Gold alloy, I'm certain they are not plated. That being said, there was no other visible gold on the board and the pins where soldiered to the copper circuitry with what appears to be plain lead/tin solider, this makes me wonder if they are not gold, I thought tin/lead solider and Gold components where never combined? I haven't dissolved the contacts to verify the possible values - I'm not yet comfortable enough with the acid recovery processes to feel confident that I would not waste values.

-Bel

 

[element47]

FYI, you should be able to capture some date of mfg information from any one of the chips that were affiliated with said drives. Usually you'll be able to find some 4-digit numbers like 9146 or 8926 (with no letter prefixes) which would give you a date of manufacture of 1991 or 1989 respectively.

Secondly, unless you are talking about large numbers of these items, the amounts of recoverable gold in even a couple dozen of these type items is awfully small.

 

[Claudie]

FYI, you should be able to capture some date of mfg information from any one of the chips that were affiliated with said drives. Usually you'll be able to find some 4-digit numbers like 9146 or 8926 (with no letter prefixes) which would give you a date of manufacture of 1991 or 1989 respectively.

Secondly, unless you are talking about large numbers of these items, the amounts of recoverable gold in even a couple dozen of these type items is awfully small.

Large or small, Gold is Gold....

 

[Militoy]

...It appears that the metallic components in these particular DIP switches may in fact be solid Gold alloy, I'm certain they are not plated....

I suspect you may find the alloy is plated brass, beryllium copper, or phosphor bronze. It's possible that someone at some time made solid gold dip switches - but if they had that kind of money to spend, and were going after performance - both OFHC copper and silver have much better conductivity than gold. Any prudent engineer would select plated copper over gold alloy.

 

[Bellien]

@ element47 I'll take a look at the chips and track down the information, thank you for that tip. If the contacts are a Gold alloy, it looks like there would about a gram of material. Trivial in the grand scheme of things but orders of magnitudes better then the fingers and pins that I have been accumulating.

I suspect you may find the alloy is plated brass, beryllium copper, or phosphor bronze. It's possible that someone at some time made solid gold dip switches - but if they had that kind of money to spend, and were going after performance - both OFHC copper and silver have much better conductivity than gold. Any prudent engineer would select plated copper over gold alloy.

I wonder about that, in no way does it make sense for them to be gold given my understanding of the gold/solider/skin effect interrelationships, but it does look like gold. I do know for a fact that it is not plated, the material is homogeneous all the way through. I also do not think it is one of the copper alloys because of the softness... but my sitting here and speculating when I have them on hand is a bit stupid... I'll post back when I actually know something. Thank you for your advice.

 

[Militoy]

@ element47 I'll take a look at the chips and track down the information, thank you for that tip. If the contacts are a Gold alloy, it looks like there would about a gram of material. Trivial in the grand scheme of things but orders of magnitudes better then the fingers and pins that I have been accumulating.

I suspect you may find the alloy is plated brass, beryllium copper, or phosphor bronze. It's possible that someone at some time made solid gold dip switches - but if they had that kind of money to spend, and were going after performance - both OFHC copper and silver have much better conductivity than gold. Any prudent engineer would select plated copper over gold alloy.

I wonder about that, in no way does it make sense for them to be gold given my understanding of the gold/solider/skin effect interrelationships, but it does look like gold. I do know for a fact that it is not plated, the material is homogeneous all the way through. I also do not think it is one of the copper alloys because of the softness... but my sitting here and speculating when I have them on hand is a bit stupid... I'll post back when I actually know something. Thank you for your advice.

I'd be interested to read what you turn up, after a test with stannous, if you can dissolve a bit of one in a test tube. Sure would be interesting to find they were gold alloy!

 

[nch]

I had dismantle about 10 Hdd by now, going after neodim and berrings.
When I Intent to use actuator arms for other projects , those wires catch my attention. Back then I had no knoledge or chemicals for testing.
The hard drives I dismantle : not older then 1997 and prior 2004 . IBM, Seagate, WD and Maxtor .
I still have the actuators that catch my eyes in a box somewhere. If I found it I will put it to the test .
Thank you

 

[Bellien]

i dissembled one of the switches and dissolved it in acid, now how do I test for gold?

No, not funny? alright... :lol:



This morning I worked on the already cracked DIP switch and tried to extract a single contact. Joyfully the contact I was trying to extract (and the contact next to it) snapped off from the board with almost no effort, Inspection found that the solider had penetrated the metal and caused it to become brittle at the metal/solider junction(that got me a little excited). Now what metal readily forms solid solutions at STP? The metal above the solider is soft and easily bent, the physical comparison to annealed copper is apt.

The extracted metal was dropped into a dram vial. Muriatic was added via a pipette, Interestingly, as soon as the contacts were covered with the HCl they began to fizz(looked like H2). I waited expecting the liquid to turn blue but it did not.

After five minutes of waiting for signs of blue, I added dilute H2O2 via pipette and then set the vial in the dark.

The vial was let sit for five hours along with a vial of HCl and tin solider.

After five hours the solution over the remains of the metal switch contacts is a light yellow. A small amount tested with the fresh Stannous resulted in a very brilliant purple, positive for gold.


I assume the effervescence was the result of galvanic action between the two metals, thoughts corrections? I will post a picture of the switches and the drive as soon as the batteries are charged and my camera is found. So far I have not been able to find the number on the DIP switch (BS 8-01) in any old catalogs, I haven't tried hunting down the drives chips yet.


Opps I typed this up hours ago and left without hitting post.

 

[Smack]

I've torn into quite a few dip switches and have found that the light blue switches are the best.

 

[Harold_V]

After five hours the solution over the remains of the metal switch contacts is a light yellow. A small amount tested with the fresh Stannous resulted in a very brilliant purple, positive for gold.

All too interesting, but a description of the (solid) remains will be very revealing. Description, please? Any chance it's a gray/green color?

Harold

 

[Bellien]

The remaining solids where a grey/black color which have now resolved to a copper color.. My apologies, I tried cutting another contact with a knife and looking at the cut with a magnifying glass. The metal is so soft the knife was not actually cutting it, apparently it was just indenting the top layer. That's embarrassing!


The solution is pale green the remaining solider is black.



I think I'll dig out those wires and give them a test while I'm at it, just to see how much 'fools' gold I have managed to collect :lol: .


The DIP switch is a light blue too, it has pink knobs.

 

[Smack]

I don't tear them apart anymore as it is too time consuming for me for what I get out of them. I just leave them on the boards now and let the refinery pay me and concentrate on the better easier stuff aka cherry picking . Also, I'm not seeing that many any more as they are not used on newer stuff, so when one does show up....well, in the Gaylord box it goes.

 

[macfixer01]

I've torn into quite a few dip switches and have found that the light blue switches are the best.

I believe the robin's egg blue ones are made by CTS? I always liked the red Greyhill switches with the gold plated beads inside.

 

[flankdrive04]

I've torn into quite a few dip switches and have found that the light blue switches are the best.

I believe the robin's egg blue ones are made by CTS? I always liked the red Greyhill switches with the gold plated beads inside.

do you have a pic as a reference?

Many thanks.

 

[macfixer01]

I've torn into quite a few dip switches and have found that the light blue switches are the best.

I believe the robin's egg blue ones are made by CTS? I always liked the red Greyhill switches with the gold plated beads inside.

do you have a pic as a reference?

Many thanks.

I checked the boards I have handy and of course none has one of them on it. You can look at the pictures at the link below, see the different varieties of types 76 and 78.

http://www.grayhill.com/dipswitches/

Also check here for typical construction information: http://www.grayhill.com/UserFiles/file/DIP_Series_78_SPST-4PST.pdf

Materials and Finishes
Shorting Member (Ball): Brass, gold-plated over nickel barrier.
Base Contacts: Copper alloy, gold-plated over nickel barrier.
Terminals: Copper alloy, matte tin plated over nickel barrier.

macfixer01

 

[gold4mike]

Hello,
knife point to check, I found that the metal was the same color all the way through and about as hard as lightly annealed copper. It appears that the metallic components in these particular DIP switches may in fact be solid Gold alloy, I'm certain they are not plated.
-Bel

I got some nuts & bolts from someone I'm processing material for and he was sure they were solid gold. He had taken them to a local jeweler who had confirmed it for him. He had cut several in half with a bolt cutter and they do indeed look homogenous in color. Long story short - I dissolved several of the pieces in nitric and they left a fairly thick foil that maintained its shape well, but were absolutely not solid gold.

Looks can be deceiving.

 

[Harold_V]

Cutting plated material with shears isn't a reliable test in that the plating is relatively soft, so it is transferred across the cut, making it look as if it's solid gold. It's particularly bad when the base metal is yellow brass or light colored bronze.

The best single test for determining if an item is solid gold, or plated, is to file a notch and test the notch with a drop of nitric acid. It tells no lies, in particular when testing copper and/or nickel alloys.

Harold

Edit:
On the subject of testing----trust no one to do your testing. You are always at the mercy of the knowledge of those you select, and they may (clearly, as in this case) lack expertise necessary to make an honest assessment.

For some reason, people get the idea that a jeweler understands gold. While some may, many do not. It's no different, for them, than it is for those that drive an automobile. One need not understand how an internal combustion engine functions in order to drive a car. And so it is with a jeweler. He may understand how to fashion jewelry by various methods, but may not, and most likely does not know a thing about gold's properties.

Read Hoke, and learn to test. It is one of the most important processes you need to master if you intend to deal with gold.

 

[Gotrek]

I didn't read the whole post so sorry if this duplicate info but the heads at the end of the arms where the wires go too also contains gold.