MIEC capacitors?

[Axtman]

Is anyone familiar with MIEC capacitors? Their prices are really cheap. Thanks,

[Jon Snell]

The are supplied by a company called Everychina and come from Beijing.
Take a look for yourself; everychina.com
Personally I wouldn't as I prefer European manufacturers as they have work ethic and quality control.

[Mick Bailey]

They're made in Taiwan according to the EveryChina site; 1,Wu Jih,Tai Chung,Taiwan 414,

I've used them for many years without any issue whatsoever for replacing grey Illinois caps in Fender amps where cost is a factor. The price has increased a fair bit recently as more people have become familiar with the brand - they used to be 1/4 the price of F&T, have lower ESR and better temperature specs.

[Axtman]

The reason why I asked is a recently ordered a brand new (it actually had a 2018 date code) Sprague Atom 20uf/600v capacitor from a reputable distributor. The cap came and was leaking electrolyte! I am returning it. The price was $30! I found the same value MIEC caps on the internet for $7!

[g1]

justradios sell MIEC and they sell a lot of caps, especially in the antique radio community. If they were problematic, I think they would have dropped the line by now.

[mozz]

I asked him once what brand he was selling and he told me MIEC. I would say tube guitar amps abuse caps a lot more than most old radios. They never really run high voltage on output tubes so i doubt the initial over voltage surge is that great there. I would put them a bit less on par with Illinois caps. I don't see any spec sheets and he doesn't really differentiate between max voltage and working voltage. He does say this though.

"Note: Electrolytic capacitors should be operated no more than 75% of maximum working voltage to prolong operating life and allow some margin of safety for unexpected voltage surges."

At 450v rating that equals 337v.

That being said, he is a nice guy and have met him a few times at radio hamfests in the PA/NJ area. I'll stick with F&T until the prices drive me elsewhere.

EDIT: currently looking at Amazon and i see 22uf/450v less than $1 each free shipping over $25

[Chuck H]

The reason why I asked is a recently ordered a brand new (it actually had a 2018 date code) Sprague Atom 20uf/600v capacitor from a reputable distributor. The cap came and was leaking electrolyte! I am returning it. The price was $30! I found the same value MIEC caps on the internet for $7!

I never got a leaking one. That's either a gross product defect on an untested part or some kind of damage? Caps left alone and uncharged wouldn't seem prone to leakage for any reason I can think of other than overheating perhaps. But FWIW I switched from Atom's to other brands because I got a couple of bad batches from Mouser. I never checked the date codes but they were purchased as new for projects in progress. They immediately exhibited symptoms of failing capacitors. Twice in a row at such expense was enough for me to stop using them. I haven't built in a while now but my last couple of amps have Nichicon PW series radial caps in them. Since I make the boards I can adjust for the radial configuration. And I don't mind doing the wrap around and shrink tube thing when I need to use them in axial mount circumstances. I've been happy with them so far but they haven't been in service more than eight years I think. So time will tell.

[Axtman]

I typically buy F&T for high voltage filter capacitors for my amp projects. Unfortunately, F&T does not make 600v caps.

Here is the leaky capacitor.

[Helmholtz]

Caps left alone and uncharged wouldn't seem prone to leakage for any reason I can think of other than overheating perhaps.

Generally ecaps shouldn't be stored for longer than 2 years. Otherwise leakage current is likely to increase.
There are special "Long Life" types, though, which can be stored for 10 years or more.
Uncharged storage is worse than operation at moderate temperatures regarding ecap lifetime. Reason is that cap charge regenerates the aluminum oxide barrier.

This said, overstorage is no explanation for physical leakage, i.e. a broken seal/vent.

[Helmholtz]

Here is the leaky capacitor.

Are you sure that white spot is dried electrolyte (i.e.salts) and not some kind of marking?

Does it dissolve with a wet Q-tip?

How does the cap measure (cap-value, ESR, leakage)?

[Axtman]

Sorry the photo is not that clear. The leakage looks just like a wart like what I see in bad old Fender filter caps that are under the doghouse.

I checked the ESR and it is high. I tested it with 3 different testers. The capacitance value is slightly higher.

[Chuck H]

I think that might be a fake/counterfeit Atom cap. The shrink and finish texture of the blue plastic looks wrong and I can see what looks to be the swirls of a cardboard tube under it. Also, the rim of the shrink plastic on atom caps is typically tight to the edges of the + side and you can usually see the actual aluminum case. That one is sloppily over the + side edge and I don't remember ever seeing that. No matter who you bought it from either. I can't remember details but there was a high end amp builder that used a bucket load of fake Atom caps in some amps several years ago.

[Axtman]

I bought the capacitor from Tube Depot.

[g1]

doesn't really differentiate between max voltage and working voltage.

I thought that was a thing of the past. Does anyone do that anymore? A cap should be able to work up to the rated value printed on it.
I think surge voltage might show up as a '% over rated voltage' for some brief time interval on the spec sheets?

[Chuck H]

I bought the capacitor from Tube Depot.

Then perhaps Tube Depot bought some caps based on price point... And they're counterfeit. That cap looks "wrong".