[GreenKeys] Plantronics tantalums

[Geoff Fors]

Yes, those are radial lead dip tantalums in the Plantronics 1280 modems, and 
the same thing happened to me when I first got mine.  It usually occurs 
after long periods of storage, in all sorts of equipment besides the 
Frederick/Plantronics.

I replace them with new ones but rated at least 10 Volts higher, which 
should still fit.  Common opinion is that the modern electrolytics work just 
as well, if you can find some that fit.

They are used as filters on the various voltage rails in the equipment, 
which usually (not always) means there is a resistor of about 100 Ohms in 
series with them, which burns up before they do, after they short.  Without 
the resistor in the design, they fail most violently and can burn holes 
through the board, catch fire and send bits of themselves everywhere as 
miniature projectiles.

There's a silver lining in all of this, namely that I have gotten quite a 
few pieces of high end, expensive test gear for almost nothing because it 
was "dead," then easily revived by replacement of a few of these shorted 
tantalums.

Geoff
WB6NVH