[NTLK] Fwd: FYI [OT] "FS: Tantalum Rework Capacitors"

Just got this announcement from the LEM List - some of you Makers out
there may be interested:
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Begin forwarded message:
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From: Jeff Walther <trag@io.com>
Date: Mon., 30. Jun.,`08 22:35:50:000 EDT
To: lemswap group <lemswap@googlegroups.com>
Subject: FS: Tantalum Rework Capacitors for Those Old Boards, $10/
set, 78759
Reply-To: trag@io.com

Replace the old leaky capacitors before (or after) they damage your
precious vintage Macintosh motherboard. I'm am selling sets of new
capacitors for reworking old Mac logic boards. A set of fifteen
capacitors is $10 shipped in the USA.

Tantalum capacitors will not leak corrosive goo onto the motherboard
the way that conventional surface mount electrolytic caps do when
they get old.

You may choose any assortment from the following choices:

Surface Mount (tantalum):
47 uF 16V AVX TAJD476K016R Size D
1 uF 35V KEMET T491B105M035 Size B
10 uF 20V AVX TAJB106M020RNJ Size B

Axial (with leads coming out the ends):

220 uF 35V Axial Electrolytic Capacitor.
470 uF 16V, 105C Axial Electrolytic Capacitor (approx. 3/4" long X
3/8" diameter)
470 uF 50V, 105C Axial Electrolytic Capacitor (approx. 1" long X
1/2" diameter)

Additional capacitors beyond the first fifteen are $.50 and do not
add to the shipping cost. If you need two sets, do not double the
$10 per set cost, just add additional caps at $.50. So, for
example, if you want 30 capacitors total, your cost is $10 for the
first fifteen plus 15 X .50 = $7.50, for a total of $17.50 per 30.

If you're outside the USA the cost will be $10 plus postage to your
location by 1st Class international, which will usually be under $3,
i.e. <$13 total.

These caps are good replacements for the old leaky electrolytic
surface mount capacitors (look like tiny fuel storage tanks on your
logic board) of the same values. The larger "fuel storage tanks" are
usually 47uF and the smaller tiny ones are either 1 uF or 10 uF.

For example, the SE/30 contains ten 47uF surface mount electrolytic
capacitors, one 1uF surface mount electrolytic capacitor, and one
each of the 220uF and 470uF axial capacitors.

The IIci contains eleven 47uF and two 10uF surface mount electrolytic
capacitors and two 470uF and one 220uF axial electrolytic capacitors.
That's actually sixteen total, so for a complete IIci set you would
need to add one additional capacitor to the $10 set of 15 for a total
of $10.50 for 16.

In my experience, the easiest way to remove the old caps is to use
two soldering pencils at one time. That way you do not put
mechanical stress on the circuit board (as you do when you heat one
side at a time). A grounded 15 watt soldering pencil is available
from Radio Shack for under $10. So, if you already have one
soldering pencil, go pick up a second one and make this job easy for
yourself.

If you try to use just one pencil, by the time you can heat the
second pad, the first will have cooled. With the one-pencil-method
you are forced to either get the entire cap and board so hot that the
solder will stay melted while you move the pencil from side to side,
or you end up bending the cold solder on one side, while lifting the
other side. That over-heating and/or bending is what typically leads
to lifted pads on the circuit board.

With the two pencil method, you just apply a pencil to each end of
the cap to be removed and wait until you can gently lift the cap with
little to no resistance. It's useful to have a damp sponge on hand,
as sometimes the cap sticks to one pencil tip or the other and it can
be wiped off on the sponge.

Jeff Walther
8107 Hillrise Dr.
Austin, TX 78759
trag@io.com

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Received on Mon Jun 30 22:57:07 2008