[N8VEM: 18401] Machine Tool IC Sockets

Discussion:

[N8VEM: 18401] Machine Tool IC Sockets - What am I doing wrong?

Andrew Bingham

2014-07-09 17:42:53 UTC

When I built my Zeta and ParPortProp boards, I used the "double wipe" IC
sockets. After reading up a bit more on the whole build process I saw a
lot of reference to using "machine tool" sockets instead due to being more
reliable. So for the SBC-188 and my SBC6120 (non-N8VEM CMOS PDP-8 board) I
used gold coated machine tool sockets. I figure I will only ever build
these boards once so I want the nicest product possible. (especially the
SBC6120 which is no longer available at all)

I made a little jig with some ESD-packaging to allow me to more easily bend
the pins on the ICs to just the right angle to fit into the sockets exactly.

However - it seems like it is *almost impossible* to remove a fully seated
IC from a machine tool socket. I literally bent an extraction tool trying
to get a 40-pin 8255 out, and ended up having to insert some tools
carefully under the IC from each end and "pry" it up from below to get it
out.

This is somewhat concerning as I go into some of my other builds - the
intent of the sockets is that if I have a bum part, or I need to switch to
a different logic series on a '74 chip for some reason, or say I want to
take the HD6120 out of my SBC6120 board to go into a hypothetical ECB
HD6120 board - the ICs will actually come out of the sockets without
breaking something!

Am I doing something wrong? Or are machine tool sockets supposed to be
that much of a PITA to get chips back out of? (Which I would understand
since they are used in MIL-STD hardware subject to vibration environments).

Andrew B

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John Coffman

2014-07-09 19:23:13 UTC

Permalink

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Andrew,<br>
<br>
I have used the machine-tool sockets for major components on a
couple of boards; e.g., CPU chips, UPD7220 (ceramic), &c.  Yes,
chips in those sockets are more difficult to extract.<br>
<br>
Before using an extraction tool, or even without an extraction tool,
a thin-bladed screwdriver is probably the best.  You should ease the
components up higher without bending any pins.  It practically take
2 such screwdrivers, because after one end is raised, unless you
prevent it from being see-sawed down when you pry up the other end,
you need to support the chip at the raised end.<br>
<br>
Be gentle.  Go easy.  They are fine sockets.<br>
<br>
--John<br>
<br>
<br>
<br>
On 07/09/2014 10:42 AM, Andrew Bingham wrote:
<blockquote
cite="mid:06928d00-dfd1-45fb-9805-5d1f1240eb64-/***@public.gmane.org"
type="cite">
<div dir="ltr">When I built my Zeta and ParPortProp boards, I used
the "double wipe" IC sockets.  After reading up a bit more on
the whole build process I saw a lot of reference to using
"machine tool" sockets instead due to being more reliable.  So
for the SBC-188 and my SBC6120 (non-N8VEM CMOS PDP-8 board) I
used gold coated machine tool sockets.  I figure I will only
ever build these boards once so I want the nicest product
possible. (especially the SBC6120 which is no longer available
at all)
<div><br>
</div>
<div>I made a little jig with some ESD-packaging to allow me to
more easily bend the pins on the ICs to just the right angle
to fit into the sockets exactly.</div>
<div><br>
</div>
<div>However - it seems like it is *almost impossible* to remove
a fully seated IC from a machine tool socket.  I literally
bent an extraction tool trying to get a 40-pin 8255 out, and
ended up having to insert some tools carefully under the IC
from each end and "pry" it up from below to get it out.</div>
<div><br>
</div>
<div>This is somewhat concerning as I go into some of my other
builds - the intent of the sockets is that if I have a bum
part, or I need to switch to a different logic series on a '74
chip for some reason, or say I want to take the HD6120 out of
my SBC6120 board to go into a hypothetical ECB HD6120 board -
the ICs will actually come out of the sockets without breaking
something!</div>
<div><br>
</div>
<div>Am I doing something wrong?  Or are machine tool sockets
supposed to be that much of a PITA to get chips back out of?
 (Which I would understand since they are used in MIL-STD
hardware subject to vibration environments).</div>
<div><br>
</div>
<div>Andrew B</div>
</div>
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Andrew Bingham

2014-07-09 19:32:46 UTC

Permalink

Okay, I just wanted to make sure I wasn't doing something horribly wrong.

The boards look so much nicer when they are done soldering before I start
putting in chips with the machine sockets. And since I generally fail at
most things hands-on requiring neatness (I must have missed that class in
first grade) I like for my boards to look as nice as possible because I
have finally gotten the hang of making nice solder joints - after doing the
ECB backplane! It's really satisfying to put it all together at the end.

Actually building all of these boards has helped me a lot with fine
detailed work. I am almost feeling ready to try some surface mount stuff.

Andrew

Post by John Coffman
Andrew,
I have used the machine-tool sockets for major components on a couple of
boards; e.g., CPU chips, UPD7220 (ceramic), &c. Yes, chips in those
sockets are more difficult to extract.
Before using an extraction tool, or even without an extraction tool, a
thin-bladed screwdriver is probably the best. You should ease the
components up higher without bending any pins. It practically take 2 such
screwdrivers, because after one end is raised, unless you prevent it from
being see-sawed down when you pry up the other end, you need to support the
chip at the raised end.
Be gentle. Go easy. They are fine sockets.
--John
When I built my Zeta and ParPortProp boards, I used the "double wipe" IC
sockets. After reading up a bit more on the whole build process I saw a
lot of reference to using "machine tool" sockets instead due to being more
reliable. So for the SBC-188 and my SBC6120 (non-N8VEM CMOS PDP-8 board) I
used gold coated machine tool sockets. I figure I will only ever build
these boards once so I want the nicest product possible. (especially the
SBC6120 which is no longer available at all)
I made a little jig with some ESD-packaging to allow me to more easily
bend the pins on the ICs to just the right angle to fit into the sockets
exactly.
However - it seems like it is *almost impossible* to remove a fully
seated IC from a machine tool socket. I literally bent an extraction tool
trying to get a 40-pin 8255 out, and ended up having to insert some tools
carefully under the IC from each end and "pry" it up from below to get it
out.
This is somewhat concerning as I go into some of my other builds - the
intent of the sockets is that if I have a bum part, or I need to switch to
a different logic series on a '74 chip for some reason, or say I want to
take the HD6120 out of my SBC6120 board to go into a hypothetical ECB
HD6120 board - the ICs will actually come out of the sockets without
breaking something!
Am I doing something wrong? Or are machine tool sockets supposed to be
that much of a PITA to get chips back out of? (Which I would understand
since they are used in MIL-STD hardware subject to vibration environments).
Andrew B
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Edward Snider

2014-07-09 20:08:40 UTC

Permalink

I use machine sockets on everything. I agree a thin-bladed standard
screwdriver is the best tool to remove chips.
Pry one end halfway up, then the other end. You can slide it underneath
the chip at that point if necessary.

Ed

Post by Andrew Bingham
Okay, I just wanted to make sure I wasn't doing something horribly wrong.
The boards look so much nicer when they are done soldering before I start
putting in chips with the machine sockets. And since I generally fail at
most things hands-on requiring neatness (I must have missed that class in
first grade) I like for my boards to look as nice as possible because I
have finally gotten the hang of making nice solder joints - after doing the
ECB backplane! It's really satisfying to put it all together at the end.
Actually building all of these boards has helped me a lot with fine
detailed work. I am almost feeling ready to try some surface mount stuff.
Andrew

G. Beat

2014-07-09 20:49:12 UTC

Permalink

I use John's method, with one addition.
Wooden Popsicle sticks are usually the correct width to fit underneath
28, 32 and 40-pin DIP.
I also use wooden chopsticks for smaller DIPs.

gb

Borut

2014-07-10 18:59:22 UTC

Permalink

I use machine tooled sockets in 32 or 40 pin sil form for everything. I cut them with stanley knife to required length. For extraction i prefer bent dental tweezers. If you ask your dentist nicely, he might have some tools he doesn't use any more.

Best regards,

Bo/

Sergey

2014-07-11 23:52:20 UTC

Permalink

That's why I actually prefer double wipe IC sockets, especially for the
prototypes. It is so much easier to extract ICs, so that you can almost do
it with your bare hands. They are also much cheaper than machined sockets.

I haven't seen any reliability issues with such sockets in my projects
(using new sockets). But sometimes in 30+ year old boards these sockets
start to behave erratically... but usually removing an IC and putting it
back fixes the issue.

Now I don't think I will need my projects in working condition in 30 years
from now... and if I will need them, I think it will be entertaining to
clean sockets/IC pins :-)