# IBM 5251



## lunker (Jul 22, 2009)

hello all,

I have picked up twenty IBM 5251 personal computers for scrap.
The Mfg date is 1979-1980. Each board has between 18-23 aluminium clad chips. they have two -six silicon chips in each chip in varying configerations.They are marked IBM 12, 18 23 25 32 55 60 etc. 

My question is are there any precious metals in this type of chip?
There is no exposed metal on the chips. Nor is there any bonding wires. I will try and post some pics. My appologies as this is my first atempt at posting a question.

Regards 
scott.


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## kelly (Jul 23, 2009)

Scott,
Welcome to the forum. I haven't done an IBM 5251, but have done an IBM 5362, which is more like a desk than a desk top, lol. It was loaded with the aluminum clad chips, see photos. If they are socketed, they should have gold or palladium, however, if they are soldered to the board, i didn't find anything but a very small amount of silver used to attached the wafer to the chip. I did find more palladium than gold in the unit I took apart. Testing solutions are your friends....Stannous chloride for testing solutions containing gold, Pd, Pt and Rh; Schwerters solution for silver metal, otherwise you're running blind.
If you don't have a copy of Hokes books, you should get them and read them. It'll make sense then. The guys on the forum help too, they are without a doubt, the most altruistic bunch of refiners I've ever had the pleasure of associating with!


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## glorycloud (Jul 23, 2009)

Wow - a 5251 twinax terminal! Probably a model 12 remote controller. 
Geez, am I ever old!!! :lol: 

I bet the chips you are referring to are the smaller and taller silver squares
that were on the pictures of the 5362 boards. (An old midrange twinax computer)

I didn't do any refining back then as those controllers were repaired instead
of trashed unless the terminal part went bad. GSP may know about the chips
on those boards. Crack one open and post some pictures. 

Thanks for the trip down memory lane!! I started selling computer equipment
in 1981 when Carter was president and interest rates were 21% Now those
were the days!!! :lol:


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## maltfoudy (Jul 31, 2009)

i'd be interested to hear too i have about a dozen of these too


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## goldsilverpro (Jul 31, 2009)

I remember some assays on IBM boards, with about 6 square Al cans each and those dots all over the board, from the early 70s. I would guess that the gold price, at that time, was $150-$200. I remember that the boards ran about $7/pound, mostly in PGMs. There were hybrid circuits under the can.

Most of my life was spent in job shop refineries. We rarely dismantled anything ourselves. Everything came in dismantled and sorted by the customer and many types of boards were mixed together. Therefore, I only learned the origin, names, and individual values of a few parts. Boards were boards, pins were pins, fingers were fingers, etc. - the mixed lots ran what they ran. I occasionally regret this, but I had no time to break things down more precisely.


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## DNIndustry (Aug 1, 2009)

I just got a crap load of these boards in a 2 giant hard disk units....


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## lunker (Aug 1, 2009)

Hey guys,
Thanks for the help.I have hokes book and am waiting for some potassium di cromate for the schwarters.

Kelly I just picked up a 5362. It almost crushed my truck! It looks like you could microwave your dinner in the front while you waited for your info.

As for the boards I have done some research for all of us with this type of scrap. The pins are palladium plated steel.
The small black blocks on the boards are chip inductors. They have either a silver palladium or pt,pd au alloy in them. The ones i have tested are all palladium silver.That would reinforce what GSP was saying. I will keep stripping and testing and will let you know if I find anything else.

P.S I don't know if it is on the forum anywhere but there is a book called electronic material handbook. It has a vast amount of info on various parts and there composition. 8) 

Cheers!


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## kelly (Aug 2, 2009)

Ya, LMAO, I think it could survive a drop out of a second story window. The big board in the center that everything connects into has Pd plated pins. I've found they pull out pretty easy even without heat. Some of the boards have some too with jumpers.
K


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## patnor1011 (Aug 2, 2009)

lunker,
I have found that book its called Electronic Materials And Processes Handbook, Third Edition - Charles A. Harper.
It is packed with info and really worth look so I will be reading that in next few days and I have put that to my rapidshare acc. I have also hotfile acc and if somebody wants download that from hotfile Ill put it there. It is rar file after unpacking contains 10 pdf files:
1. development and fabrication of ic chips
2. plastics elastomers and composites
3. ceramics and glasess
4. metals
5. solder technologies for electronic packaging and assembly
6. electroplating and deposited metallic coatings
7. pcb fabrication
8. materials and processes for hybrid microelectronics and multichip modules
9. adhesives underfills and coatings in electronics assemblies
10. thermal management materials and systems.

here is link:
http://hotfile.com/dl/14622966/6061101/Electronic_Materials_And_Processes_Handbook.rar.html

*edited - removed rapidshare link as file is now located on hotfile. also on my signature. sorry for that but I had to change rapidshare to hotfile as there you can post larger files...


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## aflacglobal (Aug 2, 2009)

Great find. I'll add this to my libary.

Thanks.


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## DNIndustry (Oct 8, 2009)

I just wanted throw this up.
a picture of the platter array in the ibm 3340 i have been picking at.


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## T3sl4 (Oct 9, 2009)

That's not a disk drive, that's a washing machine!


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## glorycloud (Oct 9, 2009)

Sweet Jesus, those were huge drives with removable platters as you referenced.
One of my first sales was in 1981 to a bank in Ft. Lauderdale that purchased a
refurbished IBM 3344-001from me for $2,500.00! :shock: 

Way back when you could actually make decent money without having to have
100% markups or more as the value of the equipment was substantial. I bet
we made at least $500 or so on that one unit. 8) 

Now I have to sell (100) 40G hard drives to see a $2,500.00 sale!!! :lol: 

Thanks for the trip down memory lane amigo!!


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## LeftyTheBandit (Oct 10, 2009)

patnor1011 said:


> lunker,
> I have found that book its called Electronic Materials And Processes Handbook, Third Edition - Charles A. Harper.
> It is packed with info and really worth look so I will be reading that in next few days and I have put that to my rapidshare acc. I have also hotfile acc and if somebody wants download that from hotfile Ill put it there. It is rar file after unpacking contains 10 pdf files:
> 1. development and fabrication of ic chips
> ...



Any chance to refresh these files it says 10 downloads max, no downloads available.


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## patnor1011 (Oct 11, 2009)

link changed to hotfile and with no restricted downloading.
http://hotfile.com/dl/14622966/6061101/Electronic_Materials_And_Processes_Handbook.rar.html


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## dick b (Oct 11, 2009)

patnor1011 

I downloaded the file, Thank You, but it came down as a rar file and when I try to open it windows doesn't recognize it and wants to know the program that created it? I tried to open it with Adobe reader but it doesn't work either.

I must be doing something wrong. any ideas?

Thanks for sharing.

dickb


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## lazersteve (Oct 11, 2009)

Download WinRAR. It's another form of zip. 

Steve


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## dick b (Oct 11, 2009)

Thanks Steve.

By the way, I've been playing with the nitric distillation process. I used the first part of the process using nitrate of soda and have got the calcium nitrate but haven't got to that part yet.

I weighed out 100ml and here's my notes.

flask tare wt - 65.45g
flask + 100ml distilled water -164.50g
distilled water weight - 99.05g

flask + 100ml distilled HNO3 wt - 187.10g
HNO3 wt - 121.65g

70% HNO3 has density of 1.42g / ml @ 4*C. All my weights at room temp.

70% = 142g/100ml
52.5% = 131.5g / 100ml
35% = 121g / 100ml
17.5% = 105g / 100ml

So it looks like I ended up with about 50% diluted HNO3

I used a O'hare triple beam balance and I suspect my weights and a little off but I had no precIpitate in the recovery flask and although the color is slightly yellow there has been no salts accumulate in the storage bottle. I haven't checked it for PH yet, but it does react well.

I'm going to send you a photo of my setup and I need to make a couple of teflon stoppers but I think it will work well as both a distiller and reactor by re-configuring the flasks and changng the direction of the condenser.
The best part is that by using Pawnbroker Bobs AB train to recover the fumes, is that there is constant vacuum in the system and positive flow into the scrubbers. Then there is virtually no NOXX to escape.

I sure appreciate all the good advice that is offered here by all you experts and I'm convinced that you do a valuable service to the members in protecting them from mistakes.

Thanks a lot.

dickb


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## lazersteve (Oct 11, 2009)

Dick,

It's unclear from your description if you are driving the reaction to completion. It sounds to me like you stopped after you collected 100mL. You should actually distill until the reaction flask is dry and no more brown fumes and thick liquid are produced. 

From the looks of your numbers I would say if you collected 100 mL @ 121.65 grams is 35% HNO3.

Be sure to keep your collection flask ice cold so you don't lose any nitric to the scrubber. It's very important to be sure the condenser drops the temperature enough from the reaction flask to the collection flask to condenser the nitric acid. If your collection flask gets too hot the nitric will pass right through the rig without condensing, especially under a vacuum.

Steve


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## dick b (Oct 11, 2009)

Steve:
Here's my mixture:
100 ml distiller water
850g NANO3
280ml H2SO4
Distilled till dry cake in Reactor and no fumes. Actually went too dry and the cake was too hard to easily break up.
Ended up with about 800ml HNO3 and dry cake. Then did my weights.
When you see the photo's it will be clear to you and I'll try and get them to you as soon as possible. I was real happy with the way it turned out.

dickb


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## patnor1011 (Oct 12, 2009)

dick b said:


> patnor1011
> 
> I downloaded the file, Thank You, but it came down as a rar file and when I try to open it windows doesn't recognize it and wants to know the program that created it? I tried to open it with Adobe reader but it doesn't work either.
> 
> ...



dick, i think that you can download winrar free on net and this will unpack that. i am going to check that tonight in work on other pc.


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## dick b (Oct 12, 2009)

patnor:

I did go and download the winrar file and also downloaded the file you uploaded, just haven't had time to get it converted. Thanks a lot for your taking the time to make the file available to the members of the forum. As soon as I get some time I'm going to open it and read what it says.

Best of luck

dickb


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