Ultra low ESR. Much confusion!

[keldeo]

Hi badcaps! So recently, me being a butterfingers, resulted in me dropping a graphics card and having the corner land directly onto a capacitor directly above the pcie slot on my Asus p5gc 775 board. Now this caused a pretty decent dent in the top of the can, so I've decided it'd ve best to replace it. However, I've ran into an issue. The current caps are Panasonic FJS, 820μf 6.3v. These are apparently "ultra low ESR" and these aren't manufactured anymore. So it seems I'm left with a few options. Put the dented cap back in, apparently it's ESR is 0.24 ohms, but the capacitance is only about 650μf. Or, I was thinking about replacing it with a polymer, with the same voltage and capacitance. I also have some 820μf 6.3v Rubycons, but for some reason the capacitance is measuring way higher than it should be. Also they are not ultra low ESR. Any FJS replacements? Thoughts?

[stj]

Re: Ultra low ESR. Much confusion!

use polymers.
it's fucked anyway - ESR should be 0.03 (datasheet page12)
whats the leakage on the rubycons? how over are they?

[keldeo]

Re: Ultra low ESR. Much confusion!

I see, thanks for the datasheet. I wasn't sure if the fj was the same as the fjs. For some reason, I thought 0.24 was low, because, if the meter Is correct (esr01) it's the same resistance as the Rubycons. I have a few other new caps I didn't test.
Also I'll be honest, I'm still fairly new at capacitors, and not sure how to find leakage. The caps I bought from mouser were the zlh series from Rubicon and bought them specifically for this cap I damaged on this board, but didn't discover the "ultra low ESR" until they were already delivered so I was hesitant to solder one in.

[stj]

Re: Ultra low ESR. Much confusion!

ZLH is not ultra-low
nobody really makes ultra-low esr electrolytics anymore - they have been surpassed by polymers
the rubycon equivelent would have been MBZ or MCZ but those have not been made in a long time

bookmark this:
http://www.paullinebarger.net/DS/
all the datasheets!

[momaka]

Re: Ultra low ESR. Much confusion!

Rubycon ZLH is fine for this board.

I have the P5GC-MX. Recapped almost everything on that board with ZLH, minus the CPU VRM (used polymers there). See this thread if you're interested:
https://www.badcaps.net/forum/showth...hlight=p5gc-mx

In all honesty, Rubycon ZLH and a few of the other ZL* series are OK for replacing ultra-low ESR caps. Same goes for Panasonic FR, FM. and FS.

Moreover, except for the CPU VRM (and sometimes RAM and/or chipset/NB VRM), most other voltage rails on many motherboards are generated by linear regulators, which don't really care about ultra-low ESR caps. Same goes for any caps that filter the PSU rails, like 3V3, 5V, and 12V. So any decent low-ESR brand cap will be fine there. In fact, older Intel boards often even use 85C GP caps there.

If O/P's P5GC board looks anything like mine, those caps above the PCI-E slot are probably for filtering the Northbridge Vcc rail, which is linearly-generated and has a good few caps in parallel. So the ESR isn't too important... hence why the Rubycon ZLH cap will work fine.

Also, if that dented Pany FJS isn't so badly damaged to have its can compromised and leaking electrolyte, it can left alone. It seems to read OK in terms of ESR and capacitance... well, as far as FJ/FJS do, anyways (I find many to read a little low on capacitance after all these years.) Or if the cap is to be replaced anyways, then I suggest saving it for "emergencies" (in case you have any other old PC hardware that might need caps.) Generally speaking, dented caps should never be used... but I find it very rare that the dent will cause the cap to short-circuit or go bad. So more often that not, you can re-use those (just not in mission-critical or very important hardware, perhaps.)

it's fucked anyway - ESR should be 0.03 (datasheet page12)

Yes, that's what its ESR should be indeed. However, don't count on those cheapo ESR meters to measure anything accurately. Mine always shows 0.00 Ohms on just about every cap above 330-470 uF, unless it's a really crummy old 85C GP cap. But that's only between pins 1 and 2. If I use the dedicated cap ESR mode between pins 1 and 3, I get higher-than-normal ESR even on good caps. So in short, DON'T trust those cheap testers to measure ESR accurately. At least mine's no good for that. And yes, I did calibrated it (multiple times.) Although not very accurate, it's still good enough to reveal truly bad/failed caps, which is what I use mine for most of the time. Bad caps will typically either have ESR 50-100x higher than what it should be, or the capacitance is getting close to or over 20% tolerance, indicating the cap oxide layer is starting to break down and the cap will fail down the road (can be days, weeks, or even years before that happens.)

[stj]

Re: Ultra low ESR. Much confusion!

don't count on those cheapo ESR meters to measure anything accurately. Mine always shows 0.00 Ohms on just about every cap above 330-470 uF, unless it's a really crummy old 85C GP cap. But that's only between pins 1 and 2. If I use the dedicated cap ESR mode between pins 1 and 3, I get higher-than-normal ESR even on good caps

i need to talk you through a firmware upgrade.

what this guy is using is something different anyway - atleast it's less functional.

[keldeo]

Re: Ultra low ESR. Much confusion!

Intersting, thanks for the data sheet link! Yes I unfortunately learned about ultra low esr after I purchased the zlh and I've seen a number of fakes on ebay, though I only get caps from mouser. But, I'm not sure I trust this $9 meter, I'll upload some images of it and the cap in question. Also the measurements of the fjs cap and a ZLH cap, also the location on the board.

Oh and thanks for the link momaka, very informative!! Not sure why, but I love this old core 2 duo and I want to keep her alive.

[stj]

Re: Ultra low ESR. Much confusion!

what is the microcontroller on that tester?

[keldeo]

Re: Ultra low ESR. Much confusion!

Right here.

[stj]

Re: Ultra low ESR. Much confusion!

thanks

[ChaosLegionnaire]

Re: Ultra low ESR. Much confusion!

don't count on those cheapo ESR meters to measure anything accurately.

me three! my esr meter always has a focked esr reading. imagine buying a cap esr meter and finding that the esr reading isnt accurate... what a bummer and oxymoron that is... it always reads 2-3x higher than what it should be. so if its a 0.02 ohm esr cap, it would read 0.05 ohms... booo!

I love this old core 2 duo and I want to keep her alive.

yea i like the core 2 series of cpus as well. good overclockability is what allows me to keep them for so long. they still work great for web surfing and even for video decoding. core 2 cpus still work great for h265 hevc full hd 1080p video decoding/watching. still no lag and no dropped frames when watching/decoding with the lav video decoder directshow filter.

[AleXis6]

Re: Ultra low ESR. Much confusion!

not sure I trust this $9 meter

usually datasheets provide information about ESR at 100kHz, sometime at 120 Hz.
but such meters use another frequency - so it is not possible to compare their measures with the datasheet for electrolytic capacitors

[Uranium-235]

Re: Ultra low ESR. Much confusion!

usually datasheets provide information about ESR at 100kHz, sometime at 120 Hz.
but such meters use another frequency - so it is not possible to compare their measures with the datasheet for electrolytic capacitors

Most of them @ 120 Hz is general use or higher ripple

100Khz is usually low ESR VRM filter caps

[keldeo]

Re: Ultra low ESR. Much confusion!

Well, sorry for being late but update , the repair is finally completed! I've actually used a Würth polymer , my friend actually had a few left over from a project and let me have one. And now it's running beautifuly. I'm typing on it now, in fact. I've experimented with different operating systems, and so far settled on an alternative os that's very fast even on the 15 year old IDE drive. Now a got a nice pc for my shed, Yes I'm pretty impressed with how well this thing can multitask and how fast it is overall. Plus I get access to legacy ports and a floppy drive!

[keldeo]

Re: Ultra low ESR. Much confusion!

usually datasheets provide information about ESR at 100kHz, sometime at 120 Hz.
but such meters use another frequency - so it is not possible to compare their measures with the datasheet for electrolytic capacitors

Now I'm really confused , how is there frequency if it's DC?

[stj]

Re: Ultra low ESR. Much confusion!

the tester uses dc pulses

[keldeo]

Re: Ultra low ESR. Much confusion!

Oh, I see thanks!