# Brown IBM boards from the 80s



## eastky (Dec 20, 2013)

I guess I will be the bearer of bad news when it comes to the brown IBM boards. This is just about the gold overlay on the connector pins. I have read all the post on the forum pertaining to them. I happen to come across some awhile back and so I started doing some research. I decided to have an assay done so I would know if they are worth looking for and buy for refining. 

I had a couple of boards that had been covered with water and mud and I was able to pull just the pad off of the connector. I called a guy about having an assay done and sent him one gram of the pads that I had pulled. It took 155 pads to make 1 gram.

I sent the pad only and not the connector. The pads are pressure bonded to the connector. The connectors had corroded enough I was able to pop the pad off the connector. On the back side of the pad you could see were the pad had been pressure bonded to the connector.

So I did some math and I have just over a gram of gold in my 6000 gold connector pads on my boards.
according to the essay from 1 gram of pads there is 30 milligrams of gold in 155 pads. That's about 6 and a half clips to get a gram of pads. Each clip has 24 pins per clip.

So to get 1 troy ounce of gold from the connector pins on the brown IBM board you would need roughly 6695 clips.
That would be 160,680 connector pins

I pulled the whole connector with the pad attached off a board and it takes 17 whole connectors to make a gram.
1 ounce of pins = 481 pins that equals roughly 20 clips and that's about 1/10 of a gram of gold per ounce of pins.

I spent $60.00 for the assay and I wont get that much gold out of my pins but if I can help members here on the forum from spending money on those boards looking at getting a return from the connector pins on those boards it was worth it to me. I would dismiss all other info posted about those connector pins.

I know Lou and goldsilverpro say to get 2 assays done. I am not going to follow their advice on that. I do have 1 more gram of just the pads. If a trusted member would like them to have an assay done I will give them up freely. 

Pictures added if they are to big will a mod please resize them. Tried to post them from photobucket but don't know how.
Sorry about the long rambling post.


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## etack (Dec 20, 2013)

where was the assey done.

thanks 

Eric


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## eastky (Dec 20, 2013)

PM sent I will call the guy tomorrow and see if he will let me post his contact info on the forum.


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## niteliteone (Dec 21, 2013)

I don't mean to be a kill joy, :shock: but what "Pins", "Connectors" or "pads" are you talking about :?: 

The only thing I can see in the pictures is a "Tabbed" connection system that has not been used for many, many years.
I don't see anything in your pictures that Could relate to the common scrap we deal with daily. 
How can we use these numbers to affect our knowledge of "Pins" we deal with daily :?: 

This info would be helpful if it was on material we all deal with daily


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## eastky (Dec 21, 2013)

These boards are still around. Call them a tabbed connector a pin a pad I don't care. The tab or pad on that connector looks like it would yield quite high. On the forum here some say it is a 10 karat gold alloy somebody said they melted some it was 16 karat. That's not true and I just wanted people to understand not to spend heavily on this type of board because of the gold contain of the tab pad or whatever they decide to classify them as.

I got my boards for free they didn't cost me anything. I read about the boards on here and decided I would have an assay done to check the content of gold. In case I came across some that was worth buying. This thread may not pertain to what you are working with but it just might help somebody from spending money on these type of boards. Thinking that they are going to get a good return on those tabs or pads.

Your not a kill joy


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## niteliteone (Dec 21, 2013)

Are you able to place arrows in your pictures to point out what material you are working with :?: 

I'm not trying to bust your chops. I have been involved in the electronics industry here in California and have never seen a board with that type of connection since College back in 1985. At which time we were taught they were obsolete and we would probably never see one in our work.


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## g_axelsson (Dec 21, 2013)

The connector is a dark green shell covering up the edge of the circuit board. The contact element is a flat tin plated brass strip soldered to the board and bent back like an U. A curved contact pad with heavy plated or rolled gold surface is spot welded to the outside end of the strip. At the back plane were pins so this is actually a female contact. In the third picture you can see both contacts with the shells still on and stripped.
At the last picture you see the metal strips with the contact surface as a bump on the end of the metal strips.
If you imagine looking along the top of the board from the side, then the metal strips "U" are sitting on both sides of the board like this 'U|U' where then board "|" goes down in the middle and the contact surfaces " ' "is at the top on the outside of each U. I hope I made some sense....

As I understand it, it was a connector type found in old IBM mainframes and mini computers roughly from the 1970-1980 era.
I ran into a trashed IBM SYSTEM3 in 1988 and that computer gave me my first 10 grams of computer gold. I have no memory of how many contacts it took to get that gold, but I still have a bag with all the pins from the back planes somewhere.
I did as eastky and broke off the contact pads, but then I dissolved the base metal in nitric and melted the foils left over. I wouldn't be surprised if it was over 16k as it formed a really hard gold alloy... I melted it together and made a casting in form of a hart that I gave to a girl... her boyfriend wasn't so happy! :mrgreen: Six months later she was my girl friend. 8) 

The foils were really thick, they fell fast through water, not as any other gold foils I've ever run into. But I wouldn't be the least surprised if there are older thicker foils and newer thinner foils. The yield could be very dependent on the age of the contacts.

Göran


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## eastky (Dec 21, 2013)

I added a picture of the connector. The green looking square pad is what I am referring to not the connector it self.
The green pad is quite thick and if you take your finger nail you can feel the edge of the pad if you try to hook your fingernail on it. 

I just wanted to let people know that the whole pad isn't gold. There is a very thin layer of gold bonded to the pad. 
Like g_axel said the gold that comes off that pad is heavy and sinks quickly. The problem is that it takes to many to 
add up to any decent weight. Its not feasible to buy these boards to recover the gold unless you get them dirt cheap.


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## niteliteone (Dec 21, 2013)

Eastky
The new picture helped identify the parts you are talking about. Thanks 8) 

Göran,
Thanks for the refresher on my memory :lol:


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## eastky (Dec 21, 2013)

niteliteone your welcome. Should have posted that pic to begin with.


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## snoman701 (Mar 18, 2017)

If a pad is one piece of metal, or one contact...then there are 96 pads on the board shown above. 48 on each side. Board/Clip/Pad/Connector/Pin...ugh! 

Using that, I get .037 grams of gold colored metal following nitric acid digestion of 94 pads (I dropped two). That would be at least fiddy five cents! And I paid 30 cents! Cue Money, by Pink Floyd. 

Goin to buy my self a gumball!


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## snoman701 (Mar 18, 2017)

For what it's worth.

After I had these in the test tube I realized I hadn't weighed the starting mass of the 94 contacts elements.

So, I ripped off 96 more...and lost two.

94 contacts (pads) before digestion = 5.459 g

3 % of 5.459 = 0.163g

I'd be happy with the above assay!


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## g_axelsson (Mar 18, 2017)

snoman701 said:


> If a pad is one piece of metal, or one contact...then there are 96 pads on the board shown above. 48 on each side. Board/Clip/Pad/Connector/Pin...ugh!
> 
> Using that, I get .037 grams of gold colored metal following nitric acid digestion of 94 pads (I dropped two). That would be at least fiddy five cents! And I paid 30 cents! Cue Money, by Pink Floyd.
> 
> Goin to buy my self a gumball!





snoman701 said:


> For what it's worth.
> 
> After I had these in the test tube I realized I hadn't weighed the starting mass of the 94 contacts elements.
> 
> ...


This shows the difficulty on relying on others yield numbers. Either your material is different than the one above, manufacturing processes improves, how well trimmed the material is affects the relative amount of gold in a sample. What I call close trimmed doesn't need to be what you call close trimmed. A better measure is gold per contact point or gold per contact, then you would remove the close cutting factor at least.

Göran


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## snoman701 (Mar 19, 2017)

Yes...now, I had a lot of metastannic acid, so I chose to just pick up the big chunks of gold and assume they were the bulk. So I'll repeat it with a HCl leach first, but I don't think it'll change much. These will go in my smelt / copper sulfate cell pile.


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## snoman701 (Mar 19, 2017)

Goran...you mentioned that you saved all of the pins from the backplanes. Were they plated with palladium? I haven't had a chance to test them.


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## g_axelsson (Mar 20, 2017)

I don't know, I have it saved somewhere but that box is hiding in the storage and haven't been seen for the last decade... it got some god company though, a couple of kilos of silver is also hiding in that box.  

Göran


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