Re: Tempest Eats EPROMs

----- Original Message -----
From: <solarfox@texas.net>
To: <vectorlist@synthcom.com>
Sent: Wednesday, October 11, 2000 9:59 PM
Subject: Re: VECTOR: Tempest Eats EPROMs

> On Wed, 11 Oct 2000 19:53:36 -0500, you wrote:
>
> >Sorry if this is a bit off topic, but does anyone else prefer machine
> >pin type sockets? I believe Gregg Woodcock also recommended those. I
>
> I _vastly_ prefer them to the cheap single-wiper type, yes; I've found
> them much more reliable in the long run.

As do/have I.

> >am having trouble with the theory here. It seems to me that if you use
> >machine pin sockets (with the conical round holes and no spring
> >tension), that if there are any differences in the pin lengths of your
> >IC, that the shortest pin might not make good contact. Whereas, with the
> >other style (solder tail?), the sockets have spring tension and apply
> >pressure to the sides of the IC pins. Pin length would therefore be
>
> The pin lengths would have to be _very_ uneven for it to make any
> difference, really... maybe a part that's been desoldered from a board,
> with trimmed leads, might present a problem, but new parts or parts
removed
> from sockets will be fine.

The pin tail begins to grip about half way down a standard length. I have
many times
had chips whose pins were trimmed which would not grip. It is easy to tell
because
you can feel them not grip on the way in and they may even jiggle! In any
case, it
has always been totally obvious to me when there has been a problem.

> >less critical. Also, It would seem to me that machine pin sockets would
> >wear quicker, in situations where an IC has to be removed and
> >reinstalled several times. (the holes could become rounded out).
>
> Well, yes, _eventually_... but if you need to insert and remove a part
> _that_ many times, you really should install a ZIF socket instead. :)
I've
> used machined-pin sockets on some prototypes, though, where I ended up
> pulling an EPROM or microcontroller in and out a couple dozen times over
> the course of development, and never had a problem with it...

I have never heard, nor would I ever expect, that a machine pin socket's
holes would
wear. Have you looked at them? They are VERY thick! What will happen,
however,
is the legs of the IC will be crimped a tad more each time the chip goes
in/out. Eventually
(and I am talking after scores/hundreds of times) the legs may be so curved
that they
no longer make good contact. The solution? Flatten then back out with a
pair of pliers.

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Received on Wed Oct 11 23:47:20 2000