[Premium-Rx] Tantalums again

[Dan Rae]

On 5/24/2012 6:39 AM, antonio wrote:
> Hi all,
>
> I'm going to gradually replace almost all of the tantalums on my 1792.
I did that with my first 1792 because it came to me with four or five 
shorted Tantalums.  It is /not/ something that I would recommend and 
certainly would not do again...  It took me a week of spare time to do 
it.  But this was more than ten years ago, and they were not so easy to 
come by then.

First off, in the 1792, at least all those I have worked on, all the 
through hole component leads have been cut off in such a way that they 
have a kind of "fish tail" at the end and will not pass through the 
holes even with the solder removed.    Secondly there is no heat relief 
on the ground holes, and since the A4 board is extra thick and the holes 
are plated through, all those connections are really hard to undo and 
clean out, even with very good de-soldering equipment.

Since then I have had maybe two or three tants die in my herd of several 
1792s and 6790/GMs and have replaced those as and when needed.

The only time I have seen any collateral damage in either was when I had 
one die in the 20 V power supply which was pretty spectacular since it 
burnt up the printed circuit board, and another on the A6A1 board which 
fried a trace on the A9 board.   That one in the power supply is the 
only one that I think is worth replacing as a matter of course and then 
not with a bead type of tant, since it is not protected by any current 
limiting upstream.

73 - Dan

ac6ao / g3ncr