Learning SMD capacitor markings

[rockola1454]

Hi!

I apologize if this is a repeat, I looked around and haven't found an answer yet, so I figured I would ask here

Long story short, I have a Dell M90 that began not POST'ing unless the AC cord is pulled out (gives an error about the wrong adapter, although it is the factory one, & swapping it with equivalent gives the same). I pulled up all the caps on the mobo & found 10 that seem out of range according to both my Supco cap tester & Fluke meter, some over 100mf beyond the rated value.

I'm having more difficulty than I expected trying to procure replacements. The 220 or 330 appears on all which I assume is the micro-farad value, but the voltage ratings elude me. How are the codes translated into voltages? ex, 220 73PUg, 330 72DTe, 330 732ed, 330 j73, 330 e74.

Any help is much appreciated!
-Chris

[stj]

Re: Learning SMD capacitor markings

lol, those are polymer - the value is what it says.

your problem is related to the 1wire serial bus on the charger connector, nothing to do with polymer caps.

[rockola1454]

Re: Learning SMD capacitor markings

Ohh, so you mean they are actually 73 volt, 72 volt, etc? I'm used to the electrolytics' nice round numbers like 25v, 50v, 100v.

The middle wire was my prime suspect, but I ruled it out with a continuity check on my adapter from solder joints inside the p/s to solder joints on the mobo, all 3 wires look solid even if i wiggle the plug around a good bit, and no shorts. A known good p/s resulted in the same error. I suppose it could be something else in the mobo... There are other issues as well that started at the same time, most notably the panel starts displaying what looks like tv static in color (fixed by closing the lid and reopening). The problems have gradually gotten worse over the last few weeks, which is why I started leaning toward capacitors, they were the 1st thing that came to mind as getting worse over time

[stj]

Re: Learning SMD capacitor markings

no, on the caps i mean 330 = 330uf ec.

get a chematic for the laptop, then trace the center pin across the board.

[mariushm]

Re: Learning SMD capacitor markings

The 330 and 220 are the capacitance values, what's below varies from manufacturer to manufacturer, or even series to series.

One digit may represent the voltage, the others may represent a series code, or the year/month of production.

Like the above posters say, a message like "unrecognized charger" hints to a problem related to the 1-wire identification chip inside the charger or how the laptop reads that signal - the charger has a third data signal in the jack.

Maybe the IC is blown, maybe that IC receives excess voltage from the adapter (due to a damaged zener diode or a capacitor or something, or maybe the IC got damaged due to ESD or some crap coming through that third data wire, it happens. Just because there's continuity between the pin in the connector and the psu pcb, doesn't mean it's still functional.

You would want to check the stream of bits sent by that IC as you plug it into the laptop if you're really motivated.

[rockola1454]

Re: Learning SMD capacitor markings

Thanks for the help, guys! After some long digging, i was able to find the schematic for the M90 motherboard, a Compal la-2881p. It has the capacitor voltages I was hunting for, too.

Heading out for a weekend getaway, but next week I'll dig into the schematic and see what i can figure out with the charger signal wire.

[stj]

Re: Learning SMD capacitor markings

page 43, top-letf.

[rockola1454]

Re: Learning SMD capacitor markings

Hi guys!

I ordered 10 replacement capacitors on ebay for $15 total, and after soldering them in, am happy to report that the laptop has a clean bill of health. One week and no issues! The main issues this solved for me were the display going nuts, and extreme slowness. The slowness was strange... not a HDD caching issue or something like that -- with nothing open but one browser and no hard drive activity, the laptop was barely able to display a web page. It was acting as if the CPU cache had been disabled. Now it's fast as ever again.

stj & mariushm, you guys were absolutely right, the power adapter warning was a separate issue, I still saw it after replacing the caps. Unable to find any issues tracing the center wire signal along with the schematic, I tried what I should have tried first -- sprayed contact cleaner in the jack & plug That seemed to fix it. Odd, since my meter showed 0 0hms end to end.

Thanks again for the help and advice!!!

[Agent24]

Re: Learning SMD capacitor markings

So those SMD capacitors go bad too, huh? Great.

Did you find if there were any voltage codes on them? I assume the letter may be a voltage code? Or was that just tolerance...

[rockola1454]

Re: Learning SMD capacitor markings

I never did make any sense out of the codes under the values. The best I could figure, you have to dig out a schematic to find out what they are ... Sure would be useful IMO if they just printed the value & voltage.

Laptop is still running great after the replacements, it definitely did the trick.

[budm]

Re: Learning SMD capacitor markings

They look similar NEC/TOKIN caps that has lots of problems in TOSHIBA and other laptops and in SAMSUNG TV main board.
http://www.gotexe.com/2014/12/laptop...l#.VXtsnPlVhBc

[Agent24]

Re: Learning SMD capacitor markings

If those are polymer capacitors which failed... why does this give me a bad feeling about the through-hole can type polymer capacitors all over motherboards these days?

[Wester547]

Re: Learning SMD capacitor markings

If those are polymer capacitors which failed... why does this give me a bad feeling about the through-hole can type polymer capacitors all over motherboards these days?

Those look like tantalum capacitors to me (which, in some respects, are similar to aluminum polymers). Tantalum polymers tend to be composed of manganese dioxide (their cathode material that is), which has a decomposition point of about 500*C, but tantalums, in general, whether composed of liquid electrolyte or manganese dioxide, tend to be intolerant of even slight positive and negative voltage spikes, so they are more fragile than "good" aluminum polymers and when they do fail can go up in flames in the worst case scenario. For what it's worth, Sun Microsystems banned the use of tantalums in their equipment as of 25 years ago. And the wet tantalums oddly enough have lower leakage currents and are more tolerant of precarious safety margins than the solid ones.

Nothing is perfect. Nothing is guaranteed to have a 0% failure rate. Early Fujitsu polymers were known to bloat because of the moisture intake and Sanyo "hybrid" polymers were known to cause many GeForce 6800 and Toshiba laptop (M60/M65 series) failures because they couldn't retain their specifications (ESR) over time. And NEC's Tokin proadlizer... enough said.

[Agent24]

Re: Learning SMD capacitor markings

Of course nothing lasts forever... but I see on the forum some people talking about motherboards with cheap Chinese polymer capacitors and they say they will still be reliable because they are polymer... I wonder how true that really is?

I'm sure the good Japanese brands can make good polymers just as they can make good capacitors anyway... but the other\Chinese\Taiwan polymers? Hmm....

[stj]

Re: Learning SMD capacitor markings

the chinese are fast learners.
i wouldnt be surprised if the chinese / wurth-technik etc are as good as the japanese.
now that the japanese have learned what not to do and been the early adopters.

[Agent24]

Re: Learning SMD capacitor markings

the chinese are fast learners.
i wouldnt be surprised if the chinese / wurth-technik etc are as good as the japanese.
now that the japanese have learned what not to do and been the early adopters.

Sure the Chinese might be fast learners (or more likely, imitators) but also big cost cutters too!

Why are the 'normal' Chinese electrolytics still rubbish after all these years? Surely not that incomplete formula thing... they must have copied a decent one by now... I think their stuff is just plain bad! Inferior materials and shoddy production quality.

[Wester547]

Re: Learning SMD capacitor markings

I agree with stj. The Chinese are capable of faking just about anything now adays so convincingly that it would be almost impossible to tell the counterfeits apart from the genuine (IMO). The crappy brands are mainly based in Taiwan and China because that happens to be where most of the "cheap" companies are based in. They can make quality products just like anyone else but they are cheap, plain and simple, and are only out to pinch coins (not do QC testing - why they don't even process most of their materials in-house). So their quality suffers as a result.

Japanese brands.... Chemi-con doesn't seem to be capable of making good quality ultra low ESR motherboard electrolytics (KZG, KZJ, KZV, TMJ, TMV), but that doesn't seem to taint people's views of them. Well, either they are not capable despite the decade's worth of years that KZG has been in production (2001-2013 at least) or they are not aware of the flub ups they made, but even then, they had a long time to improve the manufacturing process and it didn't happen with those series. In NCC's defense, though, they discontinued KZJ and KZV eight years ago.

As for polymers... I don't constantly hear, or am not aware of Chinese or Taiwanese polymers going bad at the frequency that their electrolytics do. It may still be too early to tell, but I think mockingbird is right when he says that they do not exhibit the same failure because polymers are ultimately more stable for a number of reasons (higher conductivity, doesn't dry up over time, doesn't have a negative temperature coefficient, etc).

Stolen formula? IMO, that was just a rumor and was never fully supported. Passive components magazine had a follow-up issue where they cleared up many things, such as where Teapo get their materials from (not just their electrolyte, and it certainly isn't Japan even though that's what they held claim to). It was also clarified that Sanyo/Suncon didn't sell their electrolyte to Jamicon, that it was supposedly a company called "Lien Yan" (though they denied it as well) and not Ltec behind the "stolen formula" (assuming that actually happened, I think it was just shoddy materials like Agent24 said that doomed all those Chinese capacitors), etc.

[stj]

Re: Learning SMD capacitor markings

btw, what's inside a poly can?
is it just a solid block with electrodes either side?

i cant help thinking we are being robbed wih poly pricing compared to electrolytics that are actually pretty complex to make.

[Wester547]

Re: Learning SMD capacitor markings

"Can" polymers (not the hybrid ones) are either impregnated with TCNQ complex salt (organic semiconductor material), polyaniline (conductive functional polymers, high conductivity, stability, and high melting point), polypyrrole (conductive functional organic polymers, higher conductivity, stability, and higher melting point), or polyethylene (conductive functional polymers, highest conductivity, stability, and highest melting point). Otherwise they are quite similar to lytics save by the dielectric material (polymer insulators) on the anode which is quite different and not as thin as those used in lytics, meaning lower capacitance and it's also why they don't come in very high voltages (low dielectric constant).

They have a separator sheet, aluminum etched foil, a bung (either sealed with epoxy or rubber), cathode aluminum foil, anode aluminum foil, etc, just like electrolytics. So you can bet your bottom dollar that they will explode if you overvolt them or reverse polarize them. As for why lytics are so much cheaper than polymers, the water-based solvents (whether an acid, alkali, or salt, etc...) are very cheap, that's probably why (and they have much better conductivity than non-aqueous electrolyte and other types of liquid electrolyte). But the high H2O content expands and dries up considerably with heat, and needs precise and studious manufacturing and very good quality additives and neutralizers to control the aggressiveness of the electrolyte (early Nichicon HMs and HNs, UCC KZGs and KZJs, Sanyo WFs, etc, are a good example of water-base electrolytics gone awry).

[stj]

Re: Learning SMD capacitor markings

fair enough.

btw, they blow up real good.
there was a post on a modding / OC site were a guy had poly-modded a mobo & put one in backwards.
it made tantalum failure look mild!!