How to tell if capacitors are genuine?

[JoeyJoe]

Hi,

I bought some cheap "Suntan" caps on eBay, but after being told they are shite, I bought some Panasonic ones instead. (£10 for 20).

They are 25v 1000uf, gold and black, but doesn't say "Panasonic" on them at all. Just the numbers: 902QG

Shouldn't genuine ones at least have "Panasonic" wrote on them?

Joe

Here is a picture: http://imgur.com/fb4eQKj

[tom66]

Re: How to tell if capacitors are genuine?

They should have (M) for Matshushita Industrial (Panasonic's parent company) with red writing on one side.

[JoeyJoe]

Re: How to tell if capacitors are genuine?

They have a M in a square box, followed by CE CM. You can see it on one of them in the picture: http://imgur.com/fb4eQKj.

The [M] is in gold, and there is a red number printed on the side.

[mariushm]

Re: How to tell if capacitors are genuine?

They look OK to me.

Panasonic capacitors don't have Panasonic written on them.

With the exception of FR series, all series should have a stylized M in a square with rounded corners written on them. See the attached picture.

The M is from the old name of Panasonic, Matsushita Electric Industrial Co., Ltd. For some time they used Panasonic only for some territories and product lines, then they decided to use Panasonic for everything.

Don't confuse it with a plain M, which in the capacitor world is just a code for tolerance, and it's +/- 20% I think. May be +/- 10%, I'm not sure.

The numbers should be in a dark red .. they're basically an internal code which represents the manufacturing date, production line, manufacturing batch, nothing you can use.

The top should be a T but not straight... see the picture, the bottom looks like the genuine Panasonic capacitors to me (considering the size of the capacitors)

Basically, you can't be 100% sure they're genuine, usually the fake ones don't have the bottoms with a soft rubber and shaped to have channels through where excess solder could spread, the printing on the capacitors is bad (poor resolution), the plastic for the label is not cut the same on all capacitors (all capacitors should have the same amount of plastic cover at the top and bottom), the T pressed on the top should be consistent and of good quality etc etc


(click to zoom)

[JoeyJoe]

Re: How to tell if capacitors are genuine?

Thank you,

From what you've told me, I'm 95% sure these are genuine. I have some others from a big bag of mixed caps, I can see some are Panasonic ones and they are identical to them.

Thanks!

[JoeyJoe]

Re: How to tell if capacitors are genuine?

Final question , These caps were 50p each, I have some other cheapo ones, is it any harm to use both in monitors?

I have 2 rows of 3 25v 1000uf caps, would the monitor be fine with 2 of the caps on each row being Panasonic, and the other to be the cheapo ones? Just to save on a bit?

[mariushm]

Re: How to tell if capacitors are genuine?

Good quality capacitors cost more, there's no way around it.

The LCD monitor power supplies are usually in a tight space (the monitor back side), in a metal case, with little amount of air moving around.
These power supplies get quite warm inside and the capacitors basically stay warm while the monitor runs.
Capacitors are rated for a number of hours at a temperature, for example 1000 hours @ 105c and all manufacturers agree with the general convention that for each 10c less, you get twice the lifetime. So 2000h@ 95c, 4000h@85c, 8000h@75c and so on.
If the power supply is 60-70c inside then the capacitors get weakened with time.

So it's important to use good quality capacitors in such places. Cheap capacitors can say 500-1000h@105c on them but in reality they may be relabeled 85c capacitors, they may be overrated so basically if you buy cheap capacitors your monitor may work but in a few months to a year or so it may go bad simply due to capacitor cooking itself.

In addition, these power supply are designed to work with capacitors with a particular technical property, LOW ESR. The no-name capacitors may say low esr on them but there's no standard to what "low esr" means... the Panasonic capacitors may have 0.05 ohm esr which is great, but the cheap capacitor may have 0.3 ohm esr and they could consider this great and low esr compared to their other series of capacitors they make, not compared to what everyone makes. Basically playing with words.
But 0.3 ohm may be too high for the design of that power supply and may make it work bad (it may work but not that well).

A high ESR value basically means the capacitor will heat up from within, shortening the life of the capacitor even faster.

So yeah ... basically cheaper caps may work, but eventually they're going to die soon again and may damage other things in the monitor when they die the second time.

ps. No, don't mix the capacitors in the row, it's possible they work in parallel or in series, so a weaker one may degrade sooner and cause the other capacitors in the row/series would have to work harder, basically they're gonna be "stressed".

[ben7]

Re: How to tell if capacitors are genuine?

I say the same as mariushm.

cheapo ones still might die, or the good caps might have a shorter life due to them having better ESR at first (cheapo capacitors usually have higher ESR than the good ones).

Anyways, yep, those Panasonics look genuine. Do you have a pic of the top of the capacitors? If they are a genuine panasonic part, then they should have a "T" shaped vent, with the top part of the T being curved a little.

[PeteS in CA]

Re: How to tell if capacitors are genuine?

JJ, it's like the way banks here in the states train their tellers to recognize counterfeit paper currency. They have them handle lots of genuine bills so that they know what genuine feels and looks like. The one thing that looks different to me about your caps, apparently FM series - which is very good, if genuine - and the FM caps in mariushm's pic is the formatting of the series name: yours say "CE FM"; mariushm's say "105C FM". But the other details I can see look right. Mariushm's parts seem to be a larger diameter, so that may account for the variation.

[mariushm]

Re: How to tell if capacitors are genuine?

Here's a few other pictures I have of capacitors in the FM series, made them myself at the beginning of 2012 . They don't have CE:

click to zoom



But this one DOES have CE on them ... 2200uF 16v, still from early 2012

click to zoom



Everything bought from Digikey or Farnell. Ignore the paper/scotch tape on all of them, it's just my way of keeping the capacitors sorted and organized. They come in bulk normally.

FR series comes without the M logo and with plain white/silver color:

click to zoom