Question about 85c caps vs. 105c caps

[PeteS in CA]

Re: Question about 85c caps vs. 105c caps

Thanks for the diagrams, PCB. As the saying goes, "A picture is worth ...". The thresholds I would have used, had I gone to that level of detail, would have been the thresholds for old-school +5V TTL. One extra wrinkle to add to your diagram, some noise goes below the 0V level. And if it goes sufficiently negative such spikes can have their own interesting effects. And another wrinkle, if the noise goes sufficiently high in the positive direction, some protective components in the IC become active, protecting the IC, but possibly affecting the speed. Since digital ICs are synchronized by clocks, the ICs' changing state can generate quite a bit of noise. The state change is not instantaneous, and for some 10s or 100s of picoseconds, each data output line can draw quite a bit of current. Large pulses of current plus stray inductances and capacitances can be a very noisy combination.

Significantly different coefficients of thermal expansion can do unpleasant things when different materials touch or are near each other. I recently helped a coworker diagnose and find a glass package rectifier that was probably cracked by being in contact with some epoxy adhesive of with a different thermal expansion characteristic.

Cooling air "likes" a straight, unobstructed path. Nothing's perfect, but it may be worth optimizing the air path to minimize obstruction, especially to critical areas.

Maybe some one with better knowledge could set me straight, but during spin-up the stress is both electrical (high current) and speed change (bearings). During spin-down I would think the stress might be the speed change.

[Wester547]

Re: Question about 85c caps vs. 105c caps

Thanks for the replies, everyone. Very, very interesting. I wouldn't say it's over my head - if anything else, I find all these very lucid explanations. And I figured that thermal expansion (or contracting and expanding due to heat cycles, and solder balls and joints cracking) wasn't ever good for hardware, which would explain why components tend to fail when first they start. Thanks for all your patience. I was also wondering - slightly off-topic - but I've read that the spinning up of a mechanical drive is the most arduous task for its spindle motor. Is spinning down also harder on it than just constantly spinning (which is said to be easier on the bearings) ? I mean spinning down alone, such as spinning down and shutting off, not spinning back up. But I also mean spinning down itself, just the task of doing that, not staying spun down. Also, well, since I have a small motherboard in there, there's a bit of a mess of IDE cables.... and one of them is literally touching part of the second RAM module and is kind of close to the two VR capacitors.... that's not at all apt for airflow, right? Also, a fan's ball bearing can go bad and still spin at full speed, correct?

[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

Here's some quick-dirty oversimplified drawings that should help get the idea across.
The 'No Ripple' one shows the correct Output from some IC chip.
.
If Data is "0" then volts has to rise to threshold [1.25v] to become a Data "1".
It's where volts is on the clock pulse that matters.
.
If at time T1 the ripple keeps the voltage below the 1.25v the Data won't change to a "1" and you'd get a data error.
If the Data is a file going to the drive you get a corrupted file.
It's not a mis-write so the drive isn't going to try and fix it.
There is nothing wrong with the drive, it just got bad data to save.
.

.

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[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

When your Vcc has excessive ripple/noise voltage on it, the chips will be unable to discern signal from noise, leading to errors and data corruption. Especially if a chip has data inputs that use hysteretic input circuits to square-up data signals that may have a little noise or slightly sloppy edges.

In addition, logic chips have specified ranges for how data inputs will interpreted. Under a certain voltage threshold is guaranteed to be "seen" as a "0"; over a certain other voltage threshold is guaranteed to be "seen" as a "1". Between those thresholds is an area of uncertainty in which chip performance is unpredictable. If the noise on the Vcc causes data to go into the uncertainty range, or even the range where a "1" might be seen as a "0" (or vice versa), well, bleep happens. Maybe data gets corrupted; maybe error detection/correction recognizes the error and time gets wasted trying to correct the error.

Yes to all of that.
I think without pics/drawings it might be a little over the OP's head at this point though.
.

[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

It seemed informative to me, but I'm not incredulous about your argument either. If you wish to read:

http://www.techarp.com/showarticle.aspx?artno=84

As suspected,,, journalists, not techs...
They asked someone and repeated it but they don't really know what they are talking about...

So then, bad PSU caps can cause a drive to fail in every way?

What you are missing is that ripple causes corrupted files on drives that are perfectly good.
There aren't any bad sectors involved.
The files were bad -before- they got to the drive.
~ So then later...
You are doing something and windows tells you that you have corrupted files - or it won't boot to windows because some file is bad or missing.
~ The automatic assumption is the drive is going bad.
~ Not always true....

It can cause a drive to develop reallocated sectors, pending sectors, offline uncorrectable sectors, S.M.A.R.T. errors, etc? Because before it died, the WD800JB was going down completely. HDD Sentinel reported it to be at 7% health and it had 256+ pending and reallocated sectors, numerous spin up issues, CRC errors, offline uncorrectable sectors, etc. I'm certain it had over 15,000 errors in the S.M.A.R.T. log. I know S.M.A.R.T. doesn't mean everything for a drive and most certainly does not report much about mechanical failure of a HDD, just problems with the media itself. But I do not think it should be wholly ignored because it can foretell impending failure. Not only that, but the WD800JB would click lots before it died...

mariushm covered that pretty well.

But it's definitely possible the PSU is at fault.

You asked earlier if a bad PSU could damage a drive.
~ The answer is yes.
Did it damage THAT particular drive?
By what you described, probably not.
.

[PeteS in CA]

Re: Question about 85c caps vs. 105c caps

Most integrated processors, chips and so on have some tolerance and can work at a voltage a bit different than the exact one they were designed for, for example a 5v chip would probably work between 4.7 and 5.3v.

In addition, logic chips have specified ranges for how data inputs will interpreted. Under a certain voltage threshold is guaranteed to be "seen" as a "0"; over a certain other voltage threshold is guaranteed to be "seen" as a "1". Between those thresholds is an area of uncertainty in which chip performance is unpredictable. If the noise on the Vcc causes data to go into the uncertainty range, or even the range where a "1" might be seen as a "0" (or vice versa), well, bleep happens. Maybe data gets corrupted; maybe error detection/correction recognizes the error and time gets wasted trying to correct the error.

[PeteS in CA]

Re: Question about 85c caps vs. 105c caps

The HN/HM were supposedly overfilled so chemistry had nothing to do with it.
No room for expansion causes leaks and then they dry-out.

That is the word I've heard as well. Someone forgot to reset the machine for a new, slightly smaller, case size than the previous run of parts. And we're talking fairly tiny cases. The water-based electrolyte used in Nichicon Hx (UCC KZx and all Rubycon low impedance caps) expands considerably with heat - personal observation, can't cite an online source for that. So slight overfill + heat = caps that vent and spill their electrolyte (which is highly conductive electrically).

IC chips don't work well with noise in their DC power.

When your Vcc has excessive ripple/noise voltage on it, the chips will be unable to discern signal from noise, leading to errors and data corruption. Especially if a chip has data inputs that use hysteretic input circuits to square-up data signals that may have a little noise or slightly sloppy edges.

[mariushm]

Re: Question about 85c caps vs. 105c caps

No, the power supply wouldn't cause problems like your WD drive manifested. Those are simply caused most likely by physical faults in the disc platters.

No...think of it like this.

Most integrated processors, chips and so on have some tolerance and can work at a voltage a bit different than the exact one they were designed for, for example a 5v chip would probably work between 4.7 and 5.3v.
Most devices have capacitors and other components in them to smooth out the voltage and protect the chips against power fluctuations, spikes and so on.

Even a perfect power supply, it can't supply a device with perfect 5v, because this is how the power supplies are designed. The do however try to smooth the voltage it sends as much as possible using capacitors or feedback loops inside themselves. The devices you have don't trust that the power supply will smooth out the voltage as much as it should, so they do an extra step and use those extra components to smooth everything they receive further.

When the capacitors or something else in the power supply start to go bad, the ripple will increase on the output and the quality of the power the psu delivers decreases. BUT, the extra components on your device will take over and smooth out the power a bit so it will be within acceptable range, and the device will still be happy. Eventually though, the quality of power from the power supply can become so bad this circuitry won't be able to smooth it enough to keep the device working (but if you're here, probably the motherboard and other components won't start)

The problem is integrated chips can have a certain degree of quality, some come out as worse quality but still within design specs and some come out as much better than design specs - just like you have processors that can be overclocked or not.

So some chips that were designed to work with 5v could work within a higher range of voltages and are less sensitive to ripple and spikes that go over the circuitry that tries to smooth out what comes from the power supply. On the other hand, some chips tolerate some ripple and spikes but in time, some transistors inside can get damaged or "weakened". In the worst case, the chip simply blows up.

When the chip is subjected to more ripple than it can handle, even after the circuitry near it tried to smooth out the voltage, it's possible that when it does some calculations inside, it returns a 1 instead 0 or the other way around, so this corrupt data gets sent to the disk heads which write it to disk. Next time when some application reads the data, expected 0 but was read 1, and you get blue screens or crashes.

It can also happen the other way around - the disk heads read the data correctly from platters, but when the chip translats the data to the IDE or SATA transmission protocol, errors can appear due to the chips having issues.

I have read that the components of a system often works hardest when first it turns on (which is why computers tend to fail upon boot). Does this apply for capacitors too?

Generally, motors needs much more power when they start, they have to overcome the friction inside and other things that are much too complicated to explain here. So for example, a 12v regular fan inside your computer is designed to use up to 0.2A (so 0.2x12 = 6 watts) but just when it starts up and reaches its normal rotation speed, it could use 3-6 times as much.
So, if you have a lot of fans and/or hard drives (motors inside the drives work the same), it's possible to demand more power than the power supply can deliver right away. If the power supply is going bad, it could even kill itself because of this.

Think about it this way. Let's say a 400w power supply can deliver 16A on 12v and you have six hard drives and 3 fans (cpu fan, back panel, hdd fan)
Each hard drive has a 12v @ 0.4A motor, but needs 1.2A to start (about 4s)
Each fan has a 12v @ 0.15A but needs about 0.7A to start (about 2s)
The processor will use about 30w when it starts, which is generated from 12v with about 85% efficiency, so that's about 3A

At boot, you then have 5 drives x 1.2A + 3 x 0.7A + 3A = 12A, which is pretty close to 16A. After boot, they all use only 5x0.4 + 3x0.15 + 2-5A = 4-7A.

That's why most RAID cards and some BIOSes have a tricked called "staggered start" or something like that, which turns drives one after another instead of all of the same time.


Another reason why computers often fail after a short time after boot is heat-cold cycles. As the solder on the pcb traces heats up and cools down, it's possible to get fractures or cracks in the solder, if the soldering wasn't done right or there's too little solder.
If some component is then not making proper contact, something can get damaged.

[Wester547]

Re: Question about 85c caps vs. 105c caps

It seemed informative to me, but I'm not incredulous about your argument either. If you wish to read:

http://www.techarp.com/showarticle.aspx?artno=84

So then, bad PSU caps can cause a drive to fail in every way? It can cause a drive to develop reallocated sectors, pending sectors, offline uncorrectable sectors, S.M.A.R.T. errors, etc? Because before it died, the WD800JB was going down completely. HDD Sentinel reported it to be at 7% health and it had 256+ pending and reallocated sectors, numerous spin up issues, CRC errors, offline uncorrectable sectors, etc. I'm certain it had over 15,000 errors in the S.M.A.R.T. log. I know S.M.A.R.T. doesn't mean everything for a drive and most certainly does not report much about mechanical failure of a HDD, just problems with the media itself. But I do not think it should be wholly ignored because it can foretell impending failure. Not only that, but the WD800JB would click lots before it died...

But it's definitely possible the PSU is at fault. Everything else seems fine. I have another question - I have read that the components of a system often works hardest when first it turns on (which is why computers tend to fail upon boot). Does this apply for capacitors too?

[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

Tech ARP's HDD myth page is full of shit then. [Whoever they are...]
-
With Ripple the data gets corrupted in the interface IC chips.
Those are in the controller on the mobo and it's counterpart on the drive's PCB.
It doesn't happen in the motor and it doesn't happen at the heads or disc.
The heads are recording what they were given to record, it gets corrupted on it's way there.
-
The IC chips run on +5v and/or +3.3v and the motor runs on +12v [unless it's a laptop drive].
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AND ~ Ripple does not directly cause power surges - at least not like that.
If they said that they are clearly clueless.
If you have THAT much ripple the system wouldn't even boot.
.
.
Excessive ripple could cause the voltage regulation in the PSU to wander around and and over time that could burn-out the motor controller chip who's job it is to keep the discs spinning at a constant speed.
It wouldn't be some sudden failure though.
-
So yes, bad PSU caps can slowly corrupt or even kill a drive.
Usually what happens is a chip somewhere gives out though.
.
.
. FYI
Interface chips are like language translators.
~~~~
CPU sends data to chipset.
Chipset converts 'CPU talk' to 'PCI BUS talk' and sends to on-board drive interface controller.
~~~~
Controller converts 'PCI BUS Talk' to 'SATA Talk'. [or 'IDE Talk'] and sends to the on-drive controller.
~~~~
Drive controller converts 'SATA Talk' to storable 'Drive Talk' and sends to the heads/disc.
....
....
Excessive Ripple could garble any of those *translations* resulting in corrupted files.
.
.
[A Chipset is mostly just a whole bunch of translators packed into one or two chips.]
.

[Wester547]

Re: Question about 85c caps vs. 105c caps

PCBONEZ, that's intriguing. But that doesn't mean bad PSU caps slowly kill HDDs or anything, do they? Because it was debunked on Tech ARP's HDD myth page that PSUs would slowly kill a HDD. It was stated they would "instantly" kill HDDs by sending a surge to them and frying them in an instant (or by just not being able to supply enough power, so the HDDs would fail to spin up). I don't think the PSU was the reason the WD800JB in that machine died, at least not in entirety.

[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

I found it.
That's a Samsung TMZ data sheet.

I've measured the ESR on Chemicon TMZ and those Samsung TMZ aren't even close.
Chemicon TMZ ESR is between KZG and KZJ.
.

[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

Now that you mention it.. yeah.. I've only ever seen 6.3V 1000uF TMZ in 8x11.5 .. no other values. Same goes for those 4V 680uF TMJ..

Weird thing is.. there are supposedly tons of different values and sizes out there.. lookie what I found:


What makes the whole situation even more complicated is that the only "common" TMZ's (6.3V 1000uF in 8mm) happen to be the only one that's missing in the PDF..

WTF Chemicon..!?

edit: according to info embedded in the PDF, it's from april 2004. In the PDF, the caps are described as having "white color letter on dark brown sleeve", so the ones on the ASRock board I posted a photo of must be even older than that, as they're black with golden letters

this is weird..

That is a TMZ series but I don't think it's Chemicon.

Chemicon shows their logo at the top of the page and the catalog number at the bottom in their data sheets.
That sheet has neither.
Also Chemicon Lytic part numbers begin with an E. The ones in that sheet don't.
There is also no 6.3v 1000uF 8mm shown.
.
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[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

could bad PSU caps cause ripple current without any sort of sign (the system seeming absolutely fine, you would never know it)?

PSU's always have -some- ripple so edit that to excessive ripple.

And to that... Frequently.

It's usually in that condition for months before something actually breaks and the user takes notice.
.
Excessive Ripple can be the stealth root cause of things like bad RAM or even corrupted hard drives.
IC chips don't work well with noise in their DC power.
If the chip takes an input signal and converts it to an output signal then noisy power can mean the output signal is full of random glitches. [errors]
If the IC is a RAM chip it will probably fail Memtest.
If the IC is in a drive interface it can be corrupting files on their way to the drive.
.
Even a slow system can be caused by ripple.
If the system is catching and correcting all those errors then that amount of it's resources is not available for other things.
.

[Scenic]

Re: Question about 85c caps vs. 105c caps

From what I can tell each one only comes in one size.
Like: TMZ I have only seen in 6.3v 1000uF.

Now that you mention it.. yeah.. I've only ever seen 6.3V 1000uF TMZ in 8x11.5 .. no other values. Same goes for those 4V 680uF TMJ..

Weird thing is.. there are supposedly tons of different values and sizes out there.. lookie what I found:


What makes the whole situation even more complicated is that the only "common" TMZ's (6.3V 1000uF in 8mm) happen to be the only one that's missing in the PDF..

WTF Chemicon..!?

edit: according to info embedded in the PDF, it's from april 2004. In the PDF, the caps are described as having "white color letter on dark brown sleeve", so the ones on the ASRock board I posted a photo of must be even older than that, as they're black with golden letters

this is weird..

[Wester547]

Re: Question about 85c caps vs. 105c caps

I don't necessarily imagine that, because you're right, how effectual a capacitor is depends on how hard it is worked. I was just curious, but thanks again for the information. Another question... could bad PSU caps cause ripple current without any sort of sign (the system seeming absolutely fine, you would never know it)?

[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

You can add a bunch of older ASRocks to that list too. I've got an ASRock K7VT4-4X where all the 6.3V 1000uF caps are TMZ's. None of them bad.. yet.
Seen a bunch of these back then and didn't replace them..
TMV's on the other hand.. most of the ones I've seen were bad already (popped the rubber bung out as they don't have a vent (4V 680uF))
The ones on my Abit motherboard are still OK (visibly at least). They're in parallel with chemicon polys though, so that might be part of the reason why they're not dead yet


edit: wait a second.. while I was looking at the 2nd photo again, I noticed a "Z" on the brown cap in the (blurry) foreground. Guess what? More TMZ's :O
Different style this time though. They look exactly like KZG's at first, which is what I thought they were the whole time

I've seen a number of TMZ not bloat but with a little leakage trail out the bottom.
.
There are three TMx I know of but the third one is pretty rare and I've only seen them one online.
Keep forgetting what series it is.
.
[Edit:] Oh...-- See the pic Bonez!
Yes TMZ, TMV, TMJ
From what I can tell each one only comes in one size.
Like: TMZ I have only seen in 6.3v 1000uF.
.
.

[PCBONEZ]

Re: Question about 85c caps vs. 105c caps

But I would imagine that the HN/HM issue would take a couple of years (of notable running time) or so to surface, and that the Taiwan aluminum problem might take a bit longer (though again, as you said, it's probably about how many power on hours and heat the system has been subjected to)?

Why would you imagine that?
Different problems. - Different characteristics.
.
The HN/HM were supposedly overfilled so chemistry had nothing to do with it.
No room for expansion causes leaks and then they dry-out.
(There was a second HN/HM problem in 2004 I think but that was short lived.)
.
.
There are easily 100's and probably 1000's of cap manufacturers in CH and TW [some of which are very small] so any exception you can think of [good or bad] probably exists somewhere.
.
The Al used in TW comes from Chinese mining operations.
The impurities are natural - trace.
.
It's safe to assume most CH & TW caps use Al made from Chinese ore and so have those impurities but that doesn't mean they are all using the same quality end product by the time it's foil.
The best foil made from CH ore is worse than even average Japanese made cap foil because of the impurities and QA in manufacturing but not all foil made from CH ore is the same.
There are more than one producer of cap foils in CH & TW.
Companies that buy their foils don't always buy from the same place.
That means the caps they make aren't always going to be the same quality.

"Bad Cap Brand" doesn't mean the caps are ~guaranteed~ to go bad.
It means they are inconsistent and there is just no way to know if they will last or not.

That said, there are a few brands that historically are so horrible they get replaced on sight.
Which brands those are depends on who you talk to based on their own experience.
It's also vintage and device related because the most commonly used caps for an application changes over time.
Someone that usually does P-3 boards will have a different 'replace on sight list' than someone that does P-4 boards or PSUs or screens because they see different caps.
.

[Wester547]

Re: Question about 85c caps vs. 105c caps

^ The D845PEBT2 of mine also had PS Polymers from Chemicon, along with Nichicon HDs, which is probably why, in tow with the VRs, it isn't gone yet. But I think with great cooling that the board can still last a while.

[Scenic]

Re: Question about 85c caps vs. 105c caps

The TMx caps were special order and only sold direct to manufactures.
Asus used a lot of them (meaning TMx) and AOpen at least a few.
.

You can add a bunch of older ASRocks to that list too. I've got an ASRock K7VT4-4X where all the 6.3V 1000uF caps are TMZ's. None of them bad.. yet.
Seen a bunch of these back then and didn't replace them..
TMV's on the other hand.. most of the ones I've seen were bad already (popped the rubber bung out as they don't have a vent (4V 680uF))
The ones on my Abit motherboard are still OK (visibly at least). They're in parallel with chemicon polys though, so that might be part of the reason why they're not dead yet


edit: wait a second.. while I was looking at the 2nd photo again, I noticed a "Z" on the brown cap in the (blurry) foreground. Guess what? More TMZ's :O
Different style this time though. They look exactly like KZG's at first, which is what I thought they were the whole time