ID of "Stealthy" Bad Capacitors: Flush Top, Blown Bottom Seal

[Ginguskhan]

Hi fellow badcaps forum members,

I have heard all about catastrophic capacitor failures which are very easy to identify (vented tops, oozing electrolyte solution, deformation of cylindrical shape, etc.) However, no one has really addressed caps where the bottom seal is broken and no electrolyte solution has oozed out of the bottom. Is this ok, or should these be replaced right away?

Specific case:
I have 5 year old MSI motherboard with 4x Nippon Chemicon 16v 1500uf capacitors next to the 4-pin cpu power connector, 2 have a blown bottom seal. The top is flush and flat (A-OK) on all, but looking at the base the circular plastic seal has popped out of the base of 2 of these (no leaking electrolyte solution). I tested the capacitors and they measured 6100uf (circuit of 4x 1500uf caps). No stability issues with motherboard, posted voltages in BIOS A-OK.

Everything indicates that these caps are ok, except for visual inspection. Why have they not lost any capacitance ability? Are these caps fine?

[370forlife]

Re: ID of "Stealthy" Bad Capacitors: Flush Top, Blown Bottom Seal

Are they pushing out the bung on the bottom, or are they just bent?

Sometimes capacitors are not always soldered on flat from the factory or get pushed sometime in their life.

[Ginguskhan]

Re: ID of "Stealthy" Bad Capacitors: Flush Top, Blown Bottom Seal

I guess the "bung" has come out of them, but no electrolyte solution:
They are mounted level with the board, about 1.5mm separation between the edge diameter of the cap and the PCB surface, but the "bung" has filled the gap. Ive attempted to take pics, but it is almost impossible to get it to focus and get the lighting right.

[Toasty]

Re: ID of "Stealthy" Bad Capacitors: Flush Top, Blown Bottom Seal

Some are made to have the bung extend down a bit on both sides (like feet) to prevent the cap from being mounted too tight to the board.

See the attached pic, perhaps it's what you're seeing.

>>but it is almost impossible to get it to focus and get the lighting right.<<

Mirror.

Toast

[PCBONEZ]

Re: ID of "Stealthy" Bad Capacitors: Flush Top, Blown Bottom Seal

Hmmm, Bungs with feet.

Anyway,
if it's not feet the cans may to push up quite a ways before they leak.
Bungs can be pretty deep. . . Ahem...

[PCBONEZ]

Re: ID of "Stealthy" Bad Capacitors: Flush Top, Blown Bottom Seal

If the cans are pushing off you should replace them AND check the power supply.

If these are KZG or KZJ and suspect then just replace them.
Those Chemicon series -sometimes- have problems. [Usually heat issues.]
.

[severach]

Re: ID of "Stealthy" Bad Capacitors: Flush Top, Blown Bottom Seal

I have 5 year old MSI motherboard with 4x Nippon Chemicon 16v 1500uf capacitors next to the 4-pin cpu power connector, 2 have a blown bottom seal.

Flush mounted caps are easier to solder so most are soldered flush. Compare the ones that are still good with the bad ones. If the good ones are flush to the board and the bad ones aren't then the pressure has raised the caps against the soldered leads which tears out the insides. No different than if you had pulled on the cap with a pliers. Even if they are all raised and the two bad bungs are down then it doesn't matter. The caps are blown and should be replaced if you value the equipment. Chemicon is a good brand but has a few bad batches of caps.

If the motherboard was mounted vertically then the ooze may have fallen too far away for you to associate it with the caps. The electrolyte may have steamed away without a trace or only a non staining gas was expelled.

Everything indicates that these caps are ok, except for visual inspection. Why have they not lost any capacitance ability? Are these caps fine?

Testing 4 caps in parallel doesn't reveal much. Some caps increase capacitance at the beginning of the death spiral. I've seen single 1500uf caps packing 6200uf. Your two good caps may be on the road to ruin packing 3000uf each for the remainder of their short lives and the two bad ones could be torn and disconnected.

but it is almost impossible to get it to focus and get the lighting right.

Put a daylight colored incandescent bulb into a clamp lamp and turn macro/closeup mode on. $10 and you're a bad cap studio or you can take the pictures outside in the sunlight.

Is this ok, or should these be replaced right away?

1.5mm is too much to be the stilts on the bungs. You can see that these stilts barely come above the rim of the capacitors on any brand.

Popped tops, blown bungs, capacitance out of spec, or too much ESR. Any damage at all is reason to replace them if the equipment is valuable since a failure can result in a board that isn't practical to fix.

[Toasty]

Re: ID of "Stealthy" Bad Capacitors: Flush Top, Blown Bottom Seal

This thread continues here:

https://www.badcaps.net/forum/showthread.php?p=70558