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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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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 |
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