Old telecomm backplanes

[Kilroy2k1]

I got 50 older telecomm dropped in my lap this weekend from a friend to process and was wondering if anyone was familiar with these as a I have a couple of questions.
I've uploaded them to picpaste to make it easier for people to access a smaller size and the full size image if they so desire.

http://picpaste.com/Mar25_0001.jpg
http://picpaste.com/Mar25_0002.jpg
http://picpaste.com/Mar25_0004.jpg
http://picpaste.com/Mar25_0005.jpg

The boards were made by Stromburg-Carlson and the guy who brought them said they were late 60's early 70's boards.
He already sold the cards from the cabinets and made out like a bandit on those and was just going to toss these out till a mutual friend reminded him I dabble in the metals recovery of old computer bits.
I'll be removing the plated pins and snipping off the gold socket contacts and running them in a sulfuric cell. By my initial calculations this sure wont be a high yield task.
now onto some questions-

in the first picture I placed 3 plugs on the upper row of pins to the right, the connectors have fully plated contacts in then but still have the wire tails that the guy trimmed, the insulation on the wire actually slides off pretty easy so I may do so-so the cell can get to as much plated surface as reasonably possible but I am concerned if the little wire tails are tin or silver plated.
Will silver or tin plating on the wire badly contaminate the cell?

The plating on most of the gold pins is a pretty dull gold colour compared to PC pins and I seem to recall the dullness of the gold denoted a slightly thicker plating, if so would it be reasonable to try and estimate it at 10 or 15 micro inches as opposed to say 5 ?

I've unwound a few pieces of wire from some of the pins and the are wire portions look tarnished, would this possibly be silver coated wire?
The guy has literally a barrel packed full of this thin comms wire and asked if it was worth processing too.

Theres not much solder content that will end up on the pins but a couple of sockets did have some on them, should I do my best to keep all solder out of the sulfuric cell?

There are a lot of non gold plated pins as well, any chance these would be silver plated as well?

I currently have not studied the process for identifying silver yet but I think its in the 'to-do very soon' list now..

Thanks for any and all advice, this project wouldn't be possible without this forum.
Tom.

 

[element47.5]

Judging by some of the connectors, I would place the vintage as more in the 80's, but who cares. You may be able to snag a date code off a connector body somewhere.

That looks like it'll keep you busy for a while. Snipping off those thousands of pins would give me carpal tunnel syndrome.

It's quite possible the wire is silver coated but whether you can harvest the silver on any kind of economically feasible basis is an open question. The proportion of silver relative to copper might well imply massive nitric consumption for whatever you could get out of it.

I dealt with wire-wrap stuff long ago and far away. Believe it or not, wire-wrap is considered more reliable than soldering as a means of making connections. If it is your plan to unwrap the coiled wire away from the posts, trust me, this is not an easy task, especially multiplied by a zillion. There IS a "take-apart" wire wrap tool, typically a manual item, and IMHO, once you start trying to take those apart, you may wish to get one of those and chuck it into a drill. Or you can just chop the bundles and just pull the wires off the posts.

I believe you are looking a a towering load of work. Not to discourage you in any way, just sharing my experience.

 

[Kilroy2k1]

Pin removal is not that bad really, the one really pretty board they are not soldered in, 3 screws per socket and they push out. the others I will use a die grinder to knock them off in bulk.

Tom.

 

[etack]

I would put at least the ware part of the plating at around 30 micro inches. That is a pretty standard plating for that type of pin. the slot connector would be the lowest figure unless the are completely plated as the commonly are in higher end applications. the fully plated pins that are thin will most likely run 3-4 grams a pound.

Its the pulling pin part that sucks the most.

Eric

 

[silversaddle1]

A die grinder? Every pin you remove with a grinder you loose values. A real sharp chiesel and a hammer will work wonders on a backplane. No losses!

 

[element47.5]

Good idea, silversaddle. An air hammer and a real sharp chisel might be the ticket, if the entire connector cannot be hammered out by hitting the sharp ends of the pins. Someone posted that technique a while back as I recall. In my experience, that is tough. Usually the pins are "corrosion-bonded" to the holes through the backplane. Still, a load of pretty tedious work can be anticipated.

 

[Geo]

most of the time the pins are pressed in. i would suggest a flat piece of aluminum to sit on the small ends of the pins and tap straight down in the center of the metal piece. if you hit off center, it will just bend the pins over. when the pins are loose, pull out with pliers. i pull them without removing the wires, it saves time that way.

 

[Kilroy2k1]

Eric, Thanks for the estimate on plating. I'll hope for 30 but expect 15.. lol

silversaddle1, there is a good percentage of pins that are only plated 3/4 the way down to the board (I will check to make sure its not solder that's crept up that one quarter) so I figured no value lost there if they are just tip plated. I have a good assortment of chisels that will cut the others much closer, depending on the quantity I may even section cut the boards and boil in HCL to eliminate all solder traces first.

element 47.5, some are soldered and some are just pressed in with a friction fit and those come out pretty well.

Geo, Would you believe a couple pieces of oak and some C clamps work, popped 2 sockets with pins right out of the board.

Tom.

 

[trashmasters]

Check out "spyder scraper blades" I love them to strip boards .. You can strip thoes old boards in seconds not hours;;;O.K. I mean GOOGLE them...I hope this will help everyone that stripes boards;;;;;You will need to build an frame to place your board on ... This should be 30-45degree angle ,,placed in an catch basen and a hood from cardboard to keep everything from flying everywhere.Oh btw these blades connect to the $19.00 Harbor Fright Saw-Saw..

 

[Pikachu2000]

What on earth is a "Saw-Saw"?

 

[srlaulis]

I believe he meant to say "Sawzall". Also known as reciprocating saw.

 

[mls26cwru]

one person suggested this to me for pulling pins out of boards... find an oven that you don't want to use for baking anymore... but the board in upside down over a cookie sheet as big as the board. when the solder gets hot enough, the pins just fall out onto the cookie sheet.

I never tried it because I never had a spare oven and concerns over fumes (could be highly toxic). It seems to me like it should work though.

 

[gold4mike]

I've got a couple of hundred pounds of similar wire wrap boards and the person who informed me of their availability told me that the wires were indeed silver coated.

I plan to use the wire for cementing silver from nitric. I'll use them until a few small pieces remain undissolved and then add just enough nitric to finish dissolving the last bit of wire.

 

[Kilroy2k1]

So far I've cleaned 4 of the boards and have nearly 3lbs of pins and the number of pins I've had to cut manually has been very minor, all the good pins are press fit in the boards and come out nice and clean, it even leaves the wrapped wire on the other side of the board.

Thanks for the confirmation on the wire, too bad I think the processing would not be worth the yield to get the silver off the wires.

With the sheer volume of pins I have I think I'll be posting in the elect section on how to size up the cell.. lol

Thanks again everyone.
Tom.