Failed MCZ rubycons

[UraBahn]

Re: Failed MCZ rubycons

Absent from the picture are all the KZJ I unceremoniously yanked off with my fingers. :P Also some suspect Ruby MCZ were pulled in the same manner.

I got this board as a cap donor, little more. It had rubycons as well as some polymer caps of the value I was looking for, so I picked it up.

[UraBahn]

Re: Failed MCZ rubycons

That could be. The VRMs could have been managing some killer ripple.

As for pics, well I already pulled alot of caps from the board, and I think I already got rid of the problem caps, but I'll give one. However, come to think of it, this board likely came from one of those cramped little systems. Interestingly tho, this system may have used an external brick for power.

Permit me this rant: Pentium 4's have no right being in pizza boxes. No. They just put out way too flipping much heat.

[mariushm]

Re: Failed MCZ rubycons

As they're 10v rated, I would guess the 1500uF ones are probably on the 5v coming from the power supply, while the 6.3v 1800uF are on the VRM side (chosen perhaps to keep the esr low)

Are you sure it's not a problem of excessive ripple from the power supply mixed with heat from the VRMs? The 1800uF may be close enough to the heatsink to be cooled a bit by the cpu fan.

How about some pictures of the boards?

[UraBahn]

Re: Failed MCZ rubycons

I have seen blown MCZ myself, though sadly I was not paying that close attention to the uF values. I partially agree with Ratdude747, they are nowhere near as bad as KZG/KZJ with regard to thermal instability, but they seem to bloat a little bit more than I'd like. Some that seem to have silently failed (for whatever reason, I acquired this board from a scrap heap) were 6.3v, 1800uf, with date code T0604.

It could be that they are all too often used in applications that simply demand too much of an aluminum electrolytic (be it thermally, ripple-wise, or otherwise.)

To clarify EIBM's post a little, Elna don't normally make too many ultra-ESR radial aluminum electrolytic caps, but they do make them. Elna RJS (was it?) being one example. I've also seen an old Slot 1 board with big ELNA caps around the CPU slot... I may have to track it down to find out more about it.

[Wester547]

Re: Failed MCZ rubycons

It makes me ponder if there's some sort of defect in the MCZ series, in a similar way that there was with Nichicon's HN/HM series (2001-2004 date codes) and Chemicon's KZG/KZE. One bad series of capacitors is possible even from a stellar Japanese company. Of course, I don't have much experience with Rubycon's MCZ capacitors so I cannot speak much of it... but maybe with the MCZ series, the oxide layer of the capacitor is better kept with lower specs (in terms of uF and/or voltage), or perhaps something is amiss with the electrolyte or maybe ESR wise. I can see why they'd fail on motherboards out of all the places with the kind of stress and surge current they'd be subject to that way (in the same manner that capacitors are 10x more likely to fail quicker, I believe, on motherboards than they are in well designed power supplies, and in turn how they are just more likely to fail in high frequency devices that need 100% stable power).

I could be wrong, of course. It's just if there are a large reports of failure from a series of capacitors, even in well ventilated systems, then something may be wrong.

[EIBM]

Re: Failed MCZ rubycons

Elna doesn't make low esr iirc. They are more for audio applications.



Geniune MCZ is good. The only times I hear of them blowing is in super toasty usff boxes and imac G5s, both of which will cook any electrolytic cap (they are better off poly modded).

MCZ is by no means in the same category as KZG or KZJ.

#1 ELNA does make capacitors suited for system boards. I own computers with plenty of ELNAs. Please explore their website for more info.
#2 These are genuine MCZ. Now there were also MBZs nearby, and they happen to be perfect. I'm quite fond of the MBZs, very reliable.
#3 If MCZs aren't in the same category of KZG/KZJ... from my general observances, I'm seeing more dead MCZ than KZG. I have computers amply filled with both types (sigh).
And yes these ARE genuine. IBM is a respectable vendor. Furthermore, as I outlined above, only the 1500uFs failed. This is interesting.

[ratdude747]

Re: Failed MCZ rubycons

Elna doesn't make low esr iirc. They are more for audio applications.



Geniune MCZ is good. The only times I hear of them blowing is in super toasty usff boxes and imac G5s, both of which will cook any electrolytic cap (they are better off poly modded).

MCZ is by no means in the same category as KZG or KZJ.

[EIBM]

Normally rubycon is my favourite, but not when it comes to the mysterious MCZ series.

A friend of mine happened to always be talking about the MCZ series and how thermally sensitive they were. Well I ended up taking home quite a few suffering thinkcentres which had MCZs in them, generously too.

What's more curious is that only ones with a specific micro farad rating blew up.

10v, 1000uF -- OK
6.3v, 1800uF -- OK, known to silently fail (hard to replace! skinnycaps)
10v, 1500uF -- BAD BAD BAD!!!

So there's a huge variance within the MCZ series in itself.

THere were some blown up KZJ chemicons beside the MCZs as well, but that's not much of a surprise (KZJ/KZGs blow up all the time).

Without further ado, I'll have to order some replacements for these MCZs... probably panasonic, sanyo, or elna. But I'd like to know if anyone else had particular issues with *certain* MCZs.