The Hall of Shame - Badcaps Photo Montage

[memebr]

Re: The Hall of Shame - Badcaps Photo Montage

Sacon FZ... dont need to say anything else.

[pdavid]

Re: The Hall of Shame - Badcaps Photo Montage

I don't usually take capacitors apart...
so here is a little Teapo/Yageo autospy. The SC series tends to develop various failures. One is a dried 1000/16 Teapo from psu's 5vsb. Bulging and dry.
Second is a 2700/6.3 Yageo from a socket A motherboard's vrm; Not bulging, but the capacitance is way up and has some sort of corrosion inside.

[retiredcaps]

Re: The Hall of Shame - Badcaps Photo Montage

Second is a 2700/6.3 Yageo from a socket A motherboard's vrm; Not bulging, but the capacitance is way up and has some sort of corrosion inside.

I'm glad you measured the capacitance and posted a screenshot. Virtually all my bad caps measure much lower in capacitance with a multimeter.

Tom66 was the first person that I know who said some of his failed caps showed higher capacitance. Now we have more evidence.

[PeteS in CA]

Re: The Hall of Shame - Badcaps Photo Montage

I think the elevated capacitance indicates a 'lytic whose water-based electrolyte lacks the necessary inhibitor and is attacking the aluminum oxide dielectric layer. Thinning that will raise the capacitance while lowering the maximum volltage. That process would end when the maximum voltage fell below the circuit voltage, and the cap either vented or launched.

[ben7]

Re: The Hall of Shame - Badcaps Photo Montage

Interesting, because that Yageo cap seems to have burnt the paper dielectric inside.

-Ben

[PeteS in CA]

Re: The Hall of Shame - Badcaps Photo Montage

Failing 'lytics can get reeeeally hot if they don't vent quickly. OTOH, watching a 'lytic vent can be very entertaining.

[Th3_uN1Qu3]

Re: The Hall of Shame - Badcaps Photo Montage

OTOH, watching a 'lytic vent can be very entertaining.

Too bad they smell so nasty. Lytics with no vents are even more fun.

[ben7]

Re: The Hall of Shame - Badcaps Photo Montage

Failing 'lytics can get reeeeally hot if they don't vent quickly. OTOH, watching a 'lytic vent can be very entertaining.

huh, I thought they just always exploded.

So, if they get dried out then it will heat up instead of exploding?

-Ben

[Scenic]

Re: The Hall of Shame - Badcaps Photo Montage

A 'lytic cap is basically just a roll of aluminum foil in a liquid with 2 wires attached (a bit (very) over-simplified)

If there's no liquid (electrolyte) left, it'll act as a heater till it burns out (given enough current)

[mariushm]

Re: The Hall of Shame - Badcaps Photo Montage

It's not roll of aluminium if I remember correctly. It's roll of a dielectric (paper, film, other materials) and between layers of the roll there's electrolytic substance.

They explode when the electrolytic turns to gas and increases the pressure inside, causing the aluminum can to burst out of the bottom plastic or simply crack where the aluminium can has some flaw and the plastic bottom is too well locked in place..
They burn when they're shorted and the electrolytic leaked already through the vent or porous plastic bottom.

[PeteS in CA]

Re: The Hall of Shame - Badcaps Photo Montage

Long, long ago in a thread far, far away ...

The electrolyte is part of the current path in an electrolytic capacitor; the paper helps hold it in suspension between the aluminum foils. Neither the electrolyte nor the paper is the dielectric. The dielectric is a thin layer of aluminum oxide formed on the aluminum anode foil. If the electrolyte dries out (I^2 * R self-heating and/or a nearby external heat source) or leaks out, there is no current, and no heat. Internal heat happens when there is too much current or unwanted chemical reactions happen (e.g. the applied voltage is too high, the electrolyte has thinned the aluminum oxide dielectric layer (lowering the maximum voltage) or is reverse polarity). Internal gas pressure can build, due to the heat and/or due to rapid forming of the oxide layer (over-voltage or reverse voltage). If the pressure gets too high, something gives. It might be the vent scored into the top of the can; lacking that, the can might pop its bottom, by lifting just enough to release the pressure or by launching (which does relieve the pressure).

[ibcus]

Re: The Hall of Shame - Badcaps Photo Montage

Thought I would register to post a few pics of the badcaps in a Dell Optiplex GX270.

[mariushm]

Re: The Hall of Shame - Badcaps Photo Montage

Oh those poor Rubycon capacitors... just go to show even the best can fall where there's loads of heat..

[ibcus]

Re: The Hall of Shame - Badcaps Photo Montage

It was caked in dust.
The guy that brought it said he had cleaned it and hoovered (vacuumed if your American ) it out.

I'm glad he doesn't clean my house...

I'm hoping changing the caps will stop it shutting down with a thermal error, although it seems a lot of work for such an old machine.

[shovenose]

Re: The Hall of Shame - Badcaps Photo Montage

Make sure the chipset heatsink is on correctly. Those like to come loose or fall off, if I'm thinking of the correct Dell

[ibcus]

Re: The Hall of Shame - Badcaps Photo Montage

The chipset heatsink is fine, I just checked and it's not loose at all.

There is another cap that is bubbled a little where the AGP slot meets the memory slot, going to change that too, 1500uf.

[ibcus]

Re: The Hall of Shame - Badcaps Photo Montage

Caps all changed and it's working a treat.

I would have really struggled removing the heat sink mount if I hadn't found this forum, I would probably be looking for small bolts to replace the chewed up plastic pins about now instead of installing windows updates.

So, a big thank you is in order.

[timb0]

Re: The Hall of Shame - Badcaps Photo Montage

Hey so I really don't know if these are bad, it's just that all of the brown coloured one on this motherboard which is from 2008 are bulged out except for 1 which is visible in the second photo. What happened was a couple weeks ago there was this jack*ss electrician who shorted the whole circuit to the office and blew 2 PCs, this one still worked but now it turns on and hangs in windows. Booting with a CD that tests RAM hangs and so does the CPU test (UBCD 2011). Sometimes the PC won't turn on (black screen), I have to turn it off and try a few times. I would be real keen to try replacing the caps if someone else can tell me if these are really bad or they are supposed to look this way, there is no leakage or anything else but a faint smell comes from the board but it could just be my imagination.. It's a HP Compaq dx7400... What ya reckon? I guess my real question is, are there any 'Good' caps that have slight bulges, it just seems odd that it happened to almost all of the brown ones but not the other (guess the others are better quality)..

[mariushm]

Re: The Hall of Shame - Badcaps Photo Montage

The swollen ones have to be replaced. They're going bad, maybe already outside their specs.
The ones near them should also be replaced. They don't show signs of going bad, but maybe they simply were better built or they just had less electrolytic than the others and didn't generate enough gas to cause pressure on the top.

Either way, you should replace all, they're certainly a cause for your problems..

Start a separate thread in the proper section (motherboards) with the writing on the capacitors and we'll suggest replacements.

[Th3_uN1Qu3]

Re: The Hall of Shame - Badcaps Photo Montage

Those are Tk caps, known crap brand. Definitely replace all in the CPU VRM area, and around the chipset as well.