Bad Caps Version 2.0??

[TheHolylancer]

Hello guys, when I read these stories on semi accurate, I wondered if anyone here would be able to provide a explanation of what had happened, since it appears that you guys know what you are doing (or at least a few :P)

http://www.semiaccurate.com/2010/01/...-rusty-chokes/

http://www.semiaccurate.com/2010/01/...kes-part-deux/

What is going on here? Esp with the bubbles that formed, is it just moisture trying to get out or? Do any of you seen this in real life that is not from asia?

And is there going to be a bad choke website now lol?

[stj]

Re: Bad Caps Version 2.0??

i can see what happened.

look at the rusty coil - they say copper cant rust.
those coils are tinned under the laquer - tin rusts real easy.

i bet the moisture got in during the wash-phase of the pcb manufacturing while the flux was being removed.

[Wizard]

Re: Bad Caps Version 2.0??

This is not coil that you are seeing. This is a box that bobbin with copper windings fits into from bottom and sealed with epoxy.

The ferrite is a compressed metal alloy powder in a mold and sintered at high temp. Brittle and some of them rusts. It is full of tiny pores that moisture could get in if not prepped for drying process properly. These had to be very DRY before coated.

Huh? That is first time I seen a winding in the powder and compressed and sintered. Sintering happens at extremely high temp. How come the coating on the copper wire not burnt off?

Cheers, Wizard

[TheHolylancer]

Re: Bad Caps Version 2.0??

so in short, moisture got into the manufacturing process, perhaps because they were in a rush to produce as many of these chap parts for the new 1156 revamp and what nots, and thus didn't allow them to dry properly.

so this can be range wide across asus's / asrock's low end?

guess it is bad caps version 2, but much much minor if it's only asus.

[stj]

Re: Bad Caps Version 2.0??

asus build motherboards for the ps3

[robert]

Re: Bad Caps Version 2.0??

Well, the material used is powdered iron (special alloy for low losses), which is mixed with resin and then pressed together and heated to a moderate temperature to harden the resin.
The resin creates tiny spaces around the iron particles to form a sort of air gap (which is necessary to make it work).
This process is used for iron powder toroid cores (as extensively used almost everywhere), and in recent times this new type of inductor for MB use is made with embedding the coiled wire into a block of powdered iron core material.

Now, the iron can rust if theres moisture. However, the core would have to rust really bad to lead to cracking, if it has to cause enough drop in inductance to cause failiure.

Im quite sure there wont be many failiures with rusting cores.

BTW, ferrite is good, but powdered iron (or rather, a special alloy containing iron and nickel) cores of good quality can be equally low loss and just as good. Advertising often tells different things, however...

[smeezekitty]

Re: Bad Caps Version 2.0??

But if the rust escapes and rusts a lead out.

[robert]

Re: Bad Caps Version 2.0??

How should it?
Only iron can rust, the copper wire just looks rusty because some of the iron powder is stuck to its isolation.
Also, theres not enough moisture to cause real problems in any realistic timeframe. It doesnt look good, but thats about it.

As an example, i have seen transformers from equipment that was the bottom of a lake for half a year work properly again after completely drying them...Really rusted, but no electrical problems after it was completely dried.

[Pyr0Beast]

Re: Bad Caps Version 2.0??

Those coils look 'vintage'

Magnetic components like these won't fail, except for the short.

It seems like this was low quality stuff. I'd agree with powder stuck to insulation of the wire. Don't really see the rust there somehow. A cosmetic defect.