I have the PCB boards out of an old ovellet word processor
it has compleat chip sets for two z80b computers
the boards are through hole plated

my question is

how do I get the chips out without destroying the chips ???
Posted on 2003-04-26 20:00:03 by rob.rice
A touch - the kind attached to a 3in x 12in can of propane.

You might want to use a heat sheild (aluminum foil might work) and heat sinks.

Be sure to do it out doors as burning PCB really smells.
Posted on 2003-04-26 20:06:47 by eet_1024
I have tryed this add I have always ended up turning the board in to carbon
befor the chips came out and cooking the chip packages thanks any way
Posted on 2003-04-27 15:30:56 by rob.rice
Heat sink each terminal with a alligator clip with a heavy wire attached to it. Get it close as you can to the joint. Not sure if aluminum or copper will conduct heat faster.

Use a solder sucker. Looks like a hypodermic needle. You press it down with the needle part close to the joint. When the solder melts you let the piston go and it sucks the solder up.

Great for through hole desoldering.
.
Posted on 2003-04-27 18:11:55 by IwasTitan
Hi, Rob,

At home I desolder them just as IwasTitan describes.
A few more additions, though:

Check the pins are desoldered, by pushing them gently sideways with the tweezers. If the pin seems to move freely in the hole, it's desoldered. (I sometimes test that by pushing the pins towards the chip, on the component side, because they are wider).

If not, add some solder and then try again. That will give you a better thermal contact.
However, do not try immediately on the same pin. Work alternating pins on either side.

The power and ground pins may be harder to desolder. You can leave those for last. When all other pins are desoldered, use a small screwdriver to gently lift the chip while heating the pin. Make sure there is enough solder when you do that.

Remember, be gentle.

Good luck
Posted on 2003-04-28 11:55:33 by VVV
hi rob,

my way is:

1) as VVV said, a good help is add some new good tin on every pin
2) take a good solder vacum pump, so heat well a pin with the solder (but do not stay too much time on it), when the tin is very liquid put the pump on and suck all the tin. If some tin remain on, do it all again from point 1 until holes comes free.
3) do it for every pin. Then check that every pin is free at the center of the hole. So it's desoldered.

B7
Posted on 2003-04-28 14:25:35 by Bit7
the olny luck I have ever had getting ICs out of thorugh hole boards was with a copper paddle heated with a tourch but I haven't ben able to find anything to make
a paddle out of for 40 pin ICs the solder sucker leaves just enought solder to hold the pins in so well that thay pull off rather than come out but the solder sucker works fine for transtors resetors and stuff like stuff like that but not ICs
may be I coulds use a pan of oil
Posted on 2003-05-04 13:12:47 by rob.rice
You could try melting a couple tablespoons of solder and pour that over the pins.

If you have a Dremel you can grind and cut away the surrounding PCB.

You might want to reevaluate what you're trying to accomplish. Have you tried Jameco for the parts?

What do you want to use those z80's for?
Posted on 2003-05-07 03:12:42 by eet_1024
I want to build a robot even though I don't need 2 computers
I (just for the he?? of it) want two computers on it


You could try melting a couple tablespoons of solder and pour that over the pins.

YES YES YES

and I could put a clay dam around the pins YES YES YES !!!


THANK YOU
Posted on 2003-05-07 21:26:55 by rob.rice
Here is my best method - it really works - just don't start the house on fire (who me? only once :)).

http://www.asmcommunity.net/board/index.php?topic=11478&highlight=oil
Posted on 2003-05-07 21:36:56 by bitRAKE
yeh I was thinking about something like that but I was thinking about frying
the board heating it with a camp stove in a pan of oil thanks
Posted on 2003-05-08 10:48:11 by rob.rice