Testing OSCON capacitors on Motherboard...
 

Acting on a tip, I started testing the electrolytic capacitors
on a Dell GX200 MB that has video smearing problems. Well, I
ran into something I hadn't seen before, a new type of capacitor.

Apparantly SANYO has made an electrolytic capacitor with an
organic semiconductor electrolyte called: OSCON capacitors.

They are supposed to be a super capacitor in that they have extremely
low ESR over a wide range of frequencies... Kind of a cross between
a film capacitor and an electrolytic.

So, how do you test these? They MB has 9, 820uf 4V caps, and 4, 680uf 6.3V
caps. The ESR's are so low that my poor old Sencore Z-Meter hardly knows
what to do with them! Some measure 0.0 ohms, others measure 0.4 ohms.

They seem to have a very peculiar leakage characteristic, if you first put
them on to test, the leakage is low, around 7 ua, and then it starts to
rise up to 40-50ua, and then over time it drops back down to 2-3ua. After
putting the cap through this cycle, it's ESR drops from 0.4 ohms down to
0.0 ohms!

Anybody familiar with OSCON caps?

Thanks,

-Chuck Harris