GA-8I915P Duo Pro with bad Sanyo WG

[ChaosLegionnaire]

Re: GA-8I915P Duo Pro with bad Sanyo WG

hmm does this mean early production batches of ultra low esr caps from many manufacturers had issues or is that just an isolated incident? i have some suncon wg too. i had better check mine as well lol

[pfrcom]

Re: GA-8I915P Duo Pro with bad Sanyo WG

i have some suncon wg too

It wasn't one of the Suncon I put in (my first reaction), but one of the original Sanyo I hadn't replaced

Advice to replace all similar when one or more goes bad is certainly correct, but given the board is usually in storage I'll take the risk of more bad siblings

[ChaosLegionnaire]

Re: GA-8I915P Duo Pro with bad Sanyo WG

power up and run the board for a few hours every several months or so to reform the caps. that should keep them from bloating or failing in storage.

[Wester547]

Re: GA-8I915P Duo Pro with bad Sanyo WG

^ Not really...

If a liquid electrolytic is prone to generating hydrogen gas just by sitting on the shelf and hasn't been overheated or abused in any form, shape, or manner, it's probably doomed to failure. The issue of reforming electrolytic capacitors has more to do with the anodic dielectric than the electrolyte. The dielectric that separates the conductive plates is not an impeccable insulator, which allows for a small amount of current to "leak" from the electrolyte to and through the dielectric due to the potent electric fields generated by the charge on the plates when you apply bias to them. This small, ever flowing DC current is also known as leakage current, or electrons making their way through and around the dielectric, all the way down to and across the wire leads, fully discharging the capacitor over time.

When an electrolytic sits in storage, due to the fact that the dielectric is NOT a perfect insulator, small, ionic parts of the electrolyte can readily diffuse into the porous, anodic oxide layer, which can alter the crystal oxide structure and produce potential electrical defects such as ionic charge carriers. This is what causes leakage current to increase as capacitors sit in storage, especially in glycol-base electrolytes (lactone-base electrolytes have the advantage of not being able to penetrate the dielectric as easily), although such electrolytes are very effective at restoring the oxide layer once current is flowing and a voltage has been applied to the plates.

This is completely seperate, again, from capacitors which will produce excessive amounts of hydrogen gas without ever having been installed in a circuit. And it's also distinct from capacitors that have issues with water-driven corrosion due to ineffective inhibitors, which will allow the electrolyte to actively attack the dielectric until it is no more. Capacitors with a poor pH balance will suffer from similar issues, where the aluminum oxide dissolves into the electrolyte until it is again no more. Without getting any more verbose, it's safe to say that those older 1000uF 6.3V 8mmx11.5mm WG simply suffer from bad electrolyte...

[momaka]

Re: GA-8I915P Duo Pro with bad Sanyo WG

Yup, exactly. ^

It doesn't matter if you reform caps to rated voltage or not - bad caps are bad caps. I've noticed this with quite a few of the bad brands/series. Reforming some of my "going bad" caps (that haven't failed quite yet) did not seem to improve their leakage current at all, and they still showed abnormally high capacitance.

All that reforming does is it makes surge currents much smaller when the cap hasn't been used in a long time.

[televizora]

Re: GA-8I915P Duo Pro with bad Sanyo WG

I still keep Pentium 4 SDRAM motherboards. I guess I should get the caps and recycle them

No SD-RAM on this motherboard. SD-RAM slots have 2 notches.