pictures from a friend
the test
the new battery
final
the text used to do this mod
Code: Select all
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ZETNET-ATARIANS DATA FILES (18) Computer Internals
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Falcon Clock Chip:-
Falcon owners should be familiar with the fact that at some point in
time their real time clock will cease to function. You will no longer
have access to your talking clock,neither will your files become stamped
with the time and date that you wrote them.Very annoying if you ever
need to locate files by using the 'sort by date' function from the
desktop.
The reason for this is that the tiny lithium battery in the clock IC has
reached the end of it's life, which is somewhere between 5 and 10 years.
Falcon owners with the original clock chip are now living on borrowed
time. One indication is that your clock becomes slower and slower and
you start having to reset the time at weekly intervals.
Two solutions , but you need to be confident in stripping down your
Falcon without causing any damage,and some delicate soldering is also
required for either option :-
(1) Replace the clock chip.At present the MCCS146818BM is availiable from
Dial Electronics Ltd., (see section 3 for contact details).
(2) Leave the original chip in place. Use a sharp knife to cut through
the soft plastic top of the chip. Be careful ! The crystal is situated
at the lefthand end of the chip (the same end as the little dot marked
on the chip casing),and you don't want to cut through the crystal
connections by mistake.The knife only needs to penetrate about 1mm
into the casing. ( Left and right, is as if looking at your Falcon normally,
keyboard being nearest to you.)
Once you have cut a trapdoor into the top of the chip casing,use tweezers
and gently pick away the rubbery filling until you reveal the small
battery sitting on top of the IC chip. There is no need to attempt to
remove the old battery.You will see the two vertical contacts to which the
battery connects to the IC chip.The lefthand side one is +ve,the righthand
side one is -ve.Gently clean up these contacts. Cut through the lefthand one
using a fine file or better still a small engraving tool, at a point midway
between the battery and the upright connection.
With a soldering iron and pair of tweezers you may now remove the portion
of the battery tag remaining on the upright left hand connector. The
old battery is now well and truly disconnected.
All you have to do now is to solder two leads (about 3" in length) to each
of the upright contacts. Obtain a suitable 3 volt Lithium battery,such as a
CR2032, and you will also need a coin cell holder since one should not
attempt to solder directly to a button cell. Solder the leads that you have
already installed on the chip to the coin cell holder.
All done ! Except for finding a suitable place to stick the battery
holder to the motherboard.Don't try and place it too near the chip as
there will be insufficient room to replace the metal work when you
start to reassemble your Falcon.Find a suitable area slightly towards
the rear of the machine. I used a stickpad to secure the battery to
the motherboard.
Lastly do check the polarity before inserting your battery into it's
holder.Positive (flat side of the battery) goes to the left hand connection
on the chip. Ensure that no exposed metal parts of the battery holder can
come in contact with any other components on the motherboard or you might
have disasterous results. Mask off if necessary. Avoid the temptation to
glue the battery holder to the top of any of the adjacent computer chips
as this could cause the chips to overheat.
I have seen some postings that an alternative to the MCCS146818BM is
the DS1287 (Dallas/Maxim), possibly also the Symphony SL1287 as used
in older PCs. Both of these chips are of solid encapsulation, and the
internal battery and it's connections can only be accessed by carefully
cutting down into the chip using a dental burr. I have tried this with the
DS1287, and it is possible to do if you have the tools and patience.
Your best bet is to get a MCCS146818BM while they are still around.Make
sure that you do not get sold a MCCS146818AFN as that is a totally
different beasty. Current price for the MCCS146818BM is 250p excluding
vat and post in the UK.
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http://list.zetnet.co.uk/pipermail/zetn ... 00677.html
look at ( 18 ) Computer Internals
and this web page
http://perso.wanadoo.fr/dsavel/ds1287e.htm in english
http://perso.wanadoo.fr/dsavel/ds1287.htm in french
DIY nvram:
from Didier Mequignon
http://www.atari-forum.com/viewtopic.php?p=74545#74545
from FujiMan
http://www.atari-forum.com/viewtopic.php?p=82071#82071
Nvram remplacement guide:
from Slyfox
http://www.atari-forum.com/viewtopic.php?p=87194#87194
I hope this help some of you
(getting old!)
