What would you salvage from an old PC

Thread Starter

adam555

Joined Aug 17, 2013
858
I like the tantalum capacitors in old mother boards and dead hard drives. They are often worth $3 to $6 in todays market.
Yes, that's what I'm talking about; thanks.

There are rows full of those at least in one of the motherboards; but I don't remember if the leads are long enough to be worth it -I never bother with components that have short leads as they are useless in a breadboard-.

If you don't mind... what are tantalum capacitors good for? I mean, I have no idea which type of capacitor is good for which application and I end up using them arbitrarily.
 

Thread Starter

adam555

Joined Aug 17, 2013
858
May as well keep any heatsinks and fans, never know when they will come in handy.
Yes, a few weeks ago I got quite a few useful components from another PSU; including the fan. But there were no more fans in old 8086/8088 PCs; I think at least not until the Pentium 4.

The speaker will also come in handy.

What I'm considering is: If I add up all the money that I will save in components from the shop, then it's worth salvaging such an old PC instead of selling it on ebay for $3, $5 or even $20 (which I doubt it will ever reach that price; unless the dollar keeps on sinking at the current rate :D). Isn't it?
 
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Markd77

Joined Sep 7, 2009
2,806
Another thing to keep in mind is that sometimes old memory, etc. could be worth selling seperately. Any value in the PC is wiped out by shipping charges, but you could make money on the memory and possibly any cards, if you can say for sure that they are working.
 

ian field

Joined Oct 27, 2012
6,536
Just had a look on ebay and can't find anyone else selling them (at least not when looking for "8086"). I think there were offering a couple of 8086 motherboards, but some sort of special stuff, not the regular PCs I have at home.

Not sure anyone would get to a price high enough to cover the P&P either -they are quite heavy-.

It's such a waste... they ware so expensive when I bought them.
Apparently genuine 5150 or 5160 machines are collectible, but finding a collector with a wad of readies isn't always easy. The PSU is easier to use for projects than the ATX type because they only have the electro-mechanical on/off switch - but you have to load the +5V rail to get all the others working.

Its very difficult to recover components from the heavily multi-layer main board, so unless you specifically want a component that's on an XT board - you can probably get it much easier someplace else.
 

Cliff987

Joined Oct 2, 2012
16
Bring them to New Jersey and throw them out on the highway where all the natives dispose their garbage.

The power supplies leap out at me as probably very useful.
 

Thread Starter

adam555

Joined Aug 17, 2013
858
I think I'm going to keep the one that has the HD, and dismantle the one without it; there would be no point buying an HD for it and then try to sell it.

Dismantling is more fun than simply throwing things away. :)
 

ian field

Joined Oct 27, 2012
6,536
I think I'm going to keep the one that has the HD, and dismantle the one without it; there would be no point buying an HD for it and then try to sell it.

Dismantling is more fun than simply throwing things away. :)
It used to be possible to get 8-bit ISA IDE cards - usually the controller section of a "Hardcard".
 

ian field

Joined Oct 27, 2012
6,536
Bring them to New Jersey and throw them out on the highway where all the natives dispose their garbage.

The power supplies leap out at me as probably very useful.
Some old XT class machines had an AC fan in the PSU with an auto-transformer to cater for 110/220V - I used one of those to run an American all band radio on the local 220V supply.
 

Thread Starter

adam555

Joined Aug 17, 2013
858
Another thing to keep in mind is that sometimes old memory, etc. could be worth selling seperately. Any value in the PC is wiped out by shipping charges, but you could make money on the memory and possibly any cards, if you can say for sure that they are working.
I don't think that would be an option in this case; these older computers have the memory in ICs soldered directly to the motherboard.

Then, one of them has no cards, everything is on the motherboard; and the other only has a basic VGA card and an AT HD interface card.

Apparently genuine 5150 or 5160 machines are collectible, but finding a collector with a wad of readies isn't always easy.
These are nothing special: one is an Epson PCe, and the other is a Commodore PC20 without the 20Mb HD. And both only the main unit; no monitors or keyboards.

The PSU is easier to use for projects than the ATX type because they only have the electro-mechanical on/off switch - but you have to load the +5V rail to get all the others working.
If I could make a dual power supply, then it would be useful for me; otherwise I don't have much use for it.

Its very difficult to recover components from the heavily multi-layer main board, so unless you specifically want a component that's on an XT board - you can probably get it much easier someplace else.
Did it many times -specially years ago- but never from a motherboard.

So far I would be interested in most of the logic ICs and buffers, since I need to buy gates of all sorts pretty soon; I would also find use for the driver's motors and the speakers; perhaps some connector; the oscillators; maybe some other interesting chip (e.g. RS232, ADC, DAC, etc.) if I can find them; and then any other regular component in good condition (e.g. capacitors, inductors, diodes, etc.)

Some old XT class machines had an AC fan in the PSU with an auto-transformer to cater for 110/220V - I used one of those to run an American all band radio on the local 220V supply.
Never opened the PSU of these old PCs; so I'm kind of looking forward to see what exactly is inside. As I said before, I got quite a few useful components from a new PSU that I opened last week (e.g. transformers, comparators, regulators, heatsinks, a PWM controller, large capacitors, etc.)
 
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ian field

Joined Oct 27, 2012
6,536
I don't think that would be an option in this case; these older computers have the memory in DIP8 format ICs soldered directly to the motherboard.

Then, one of them has no cards, everything is on the motherboard; and the other only has a basic VGA card and an AT HD interface card.



These are nothing special: one is an Epson PCe, and the other is a Commodore PC20 without the 20Mb HD. And both only the main unit; no monitors or keyboards.



If I could make a dual power supply, then it would be useful for me; otherwise I don't have much use for it.



Did it many times -specially years ago- but never from a motherboard.
If the board itself is definitely scrap, the easiest way is to heat all the pins of a component at once with a modeller's pencil blowtorch - this may sound brutal, but its the best chance of heating all the pins simultaneously and quickly so the chip doesn't cook while you're struggling with it. Originally I used to use ordinary bull-nosed pliers to get hold of 14/16 pin chips, but anything bigger was a challenge - then I discovered IC extraction tweezers, big tweezers with flat hooks on the ends to get under a chip and pull it out.

Going the other way - removing a dud chip from a board you want to repair; its usually easier to shear all the pins off flush with the IC package, as long as the pin ends protruding through the solder side aren't bent, you can melt some fresh solder on the top of the pin and lift it out with the surface tension of the solder blob.
 

Thread Starter

adam555

Joined Aug 17, 2013
858
If the board itself is definitely scrap, the easiest way is to heat all the pins of a component at once with a modeller's pencil blowtorch - this may sound brutal, but its the best chance of heating all the pins simultaneously and quickly so the chip doesn't cook while you're struggling with it. Originally I used to use ordinary bull-nosed pliers to get hold of 14/16 pin chips, but anything bigger was a challenge - then I discovered IC extraction tweezers, big tweezers with flat hooks on the ends to get under a chip and pull it out.

Going the other way - removing a dud chip from a board you want to repair; its usually easier to shear all the pins off flush with the IC package, as long as the pin ends protruding through the solder side aren't bent, you can melt some fresh solder on the top of the pin and lift it out with the surface tension of the solder blob.
I always used desoldering wick for the ICs. The soldering usually comes off fairly easily if you place it straight along the rows of pins. Never tried any other method on ICs. But yes, this this going to be a real challenge; which I'm still considering. I'll probably end up doing it any way during one of those days that I get bored.
 

ian field

Joined Oct 27, 2012
6,536
I always used desoldering wick for the ICs. The soldering usually comes off fairly easily if you place it straight along the rows of pins. Never tried any other method on ICs. But yes, this this going to be a real challenge; which I'm still considering. I'll probably end up doing it any way during one of those days that I get bored.
Solder wick is utterly useless on through-plated holes.
 

tubeguy

Joined Nov 3, 2012
1,157
Works well for me too. But, if occasionally solder doesn't come off completely the first try with solder wick, just add fresh solder to the pin and try again.
 

THE_RB

Joined Feb 11, 2008
5,438
Solder wick is a slow and painful way to remove ICs from PTH PCBs.

I use a larger tip iron (60W) and add lots of solder to the entire row of the IC legs. Then heat the whole row of pins at once, and a tiny screwdriver etc as a lever under the IC and pull all the legs out at once. It can take a couple of goes on each row of legs, but I can get a chip out pretty quick.
 

Thread Starter

adam555

Joined Aug 17, 2013
858
Solder wick is a slow and painful way to remove ICs from PTH PCBs.

I use a larger tip iron (60W) and add lots of solder to the entire row of the IC legs. Then heat the whole row of pins at once, and a tiny screwdriver etc as a lever under the IC and pull all the legs out at once. It can take a couple of goes on each row of legs, but I can get a chip out pretty quick.
Don't you risk overheating the ICs with that method?

Going back to the components... just took out the Epson's motherboards... doesn't look too good in terms of useful parts; half a dozen NAND ICs and another few varied gates, a couple of inverters and buffers, 4 oscillators and another controlled by voltage, 2 dip switches blocks of 4 and 8, 512Kb RAM in 8 different chips, the 8088, BIOS and timer, and various transistors, small capacitors, resistors, and diodes with leads almost too short to be of any use.

The PSU looks rather more interesting than the motherboard. :(
 

Danm1

Joined Jul 19, 2010
69
A local used PC place near me said he makes a small profit shipping older PCs to third world countries, where they are happy to get something they can afford that works.
 
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