Date   : Mon, 06 Dec 1999 09:56:37 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: Removing ROMs from Issue 7 board

Tim <timf@...> wrote:
>Faraz Choudhry wrote:
> > obviously this requires me to remove the existing ROM chips from the
> > motherboard, and transfer them onto the new board.  The trouble is, I
[snip]
> > the other end of the chip off the board.  Is there anything you can
> > suggest?  Please help.
>
> I may be stating the obvious here, but have you tried a 'IC extraction
> tool'? It's a little plastic thingy that clips over the chip with flanges
> in between all the legs (like a wide clothes peg with teeth). They are
> very cheap. Most good electronic component suppliers should have them -
> try Maplin or CPC (if you're in the UK).
 
NO NO NO NO NO!!!!
 
Never use one of those.  They are the worst bit of sales brainwashing
outside Microsoft.
 
To use them you clip it over the IC.  You then /try/ to gently pull the IC
out.  The major flaw is that as the IC comes loose you progressively have
less and less control over the thing as it's the friction you work against
is the friction you are trying to remove.  In many cases the IC will come
loose so suddenly that you end up with massive pin damage.
 
What you should use is a BENT lever.  Using this you are working against a
static pivot - the PCB itself.  Chris may have some pictures on his
website at 8BS as he took some photos of me using mine.
 
What you need is a strip of metal, 1mm thick, about 7 to 10mm wide and
about 150mm long.  Make a clean right-angle bend about 10mm from one end. 
Ideally, do this by clamping the strip in a vice and tapping the strip
bent.
 
You now have you IC lever.
 
To use it, gently poke the bend end under then end of an IC and move the
handle end side to side.
 
                  ----
        <---\     |  |     / --->  Sideways rotation movements
             \    |  |    /
              \   |  |   /
               \  |  |  /
                \ |  | /
                  |  |
                +-|  |-+
                | ---- | <-- IC
 
                END VIEW
 
Repeat this at the other end of the IC.  Follow this by moving the handle
end away from the IC.
 
                  \      |
Pull away from IC  \     |
        <-----      \    |
                     \   |
                      \  |
                       \ |
                        \|==============  <-- IC
                         +--
 
                            SIDE VIEW
 
This way, you are pivoting against a fixed surface - the IC socket.  Your
movement isn't being controlled by the friction of the IC pins - when it
comes loose you can stop dead.  In the worst case you can only move the
tool the couple of centimetres to the PCB.  When using the pulling tool
when one end of the IC comes loose you can end up uncontrollably ripping
the rest of the IC out, destroying the pin alignment.
 
 
J.G.HARSTON RESERVES THE RIGHTS TO THE DESIGN OF THE IC LEVER.  THE
CREATION AND USE OF THE IC LEVER BY INDIVIDUALS IS UNRESTRICTED.  THE USE
OF THE IC LEVER BY OTHER THAN INDIVIDUALS IS UNRESTRICTED.  THE CREATION
OF LARGE NUMBERS OF IC LEVERS IS RESERVED TO J.G.HARSTON
 
-- 
J.G.Harston (JGH BBC PD Library) 70 Camm Street, Walkley, SHEFFIELD S6 3TR
jgh@...                - Running on BBCs & Masters with SJ MDFS FileServer
            Z80+6502/CoPro+Tubes/Econet+SJ --- http://mdfs.net/
I'm typing backwards for Christmas, Across the TCP/IP, 
            I'm typing backwards for Christmas, It's the only thing for me.