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**Topcat** · 06-18-2014, 09:31 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Originally posted by socketa View Post

There is another number written on the caps : 0338 - what is this? (is it 0.0338 impedance?)

No, that's the datecode. The cap was made the 38th week of 2003.

Here's a good replacement for those:
https://www.badcaps.net/store/produc...roducts_id=137

I do ship to Australia.

**socketa** · 06-19-2014, 06:22 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Thanks for clearing that bit up.
Reading through the forum, i see that that is a very important spec.
Have learned a bit about capacitors in the last few days.
I was looking on Ebay and they all look extremely suspect.
And note that rs-online don't readily supply the motherboard caps to plebs (unless you want 600 of them)
Is this some kind of a conspiracy?

Also have noticed, on the various datasheets, that ESR value is close to Impedence value.
For practical purposes, are they the same?

**mariushm** · 06-19-2014, 07:32 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Manufacturers reduced the volume of ultra low esr electrolytic capacitors production or even discontinued series, because most motherboards nowadays use polymer capacitors for the critical sections (if not for everything).
For example, Nichicon has discontinued their HZ, HM and HN series capacitors...

A lot of customers also tend to be more informed or eat up the marketing that says "all solid capacitors" so they look after that.

Therefore, it's possible distributors like RS-Online may not want to risk stocking such capacitors (they have to order minimum quantities, for example 5000pcs) when there's a high chance it's going to take a long time to sell them.

**socketa** · 06-19-2014, 09:16 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Thanks
So, after reading that, i thought that polymer caps are the way to go now.

I just checked out nichicon's range of conductive polymer aluminium solid electrolytic capacitors and found none that were suitable to replace my 2200uf's.
Nearly all of them were well below this capacitance value.
Why is that?

Is it because there is no demand for these capacitors now, or do the new motherboards use low value capacitors now? (i thought that they would require higher value caps, judging by how fast the modern processors are working)

So basically these discontinued caps are the only option for older motherboards now?

**mariushm** · 06-19-2014, 09:58 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Polymer capacitors are harder to produce at such high capacitance values.

Also, motherboards don't actually need that much capacitance to work, but motherboard designers use such large capacitors (and often several of them in parallel) because the bigger capacitors have lower ESR and can handle higher currents. Paralelling several capacitors further reduces the ripple.
Polymer capacitors have much lower ESR from the start and they can handle higher current ripples so it's quite normal to see polymer capacitors of lower capacitance used.

For example, while you may have 2200uF 6.3v capacitors now near the CPU, these can be replaced with.. let's say 1500uF 2.5v polymers, or 1200uF 4v... because the CPU uses less than 2 volts when running. The manufacturer used 6.3v electrolytics because that's the lowest common voltage rating for electrolytic capacitors, not necessarily because it was required by the circuit.

**socketa** · 06-19-2014, 10:55 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Thanks again,
Nicely explained

Yes, i noticed polymer ripple ratings were a lot higher.
I just had a look at the bios and saw VCore is 1.55v

I thought that capacitance was an important factor, because i read that the capacitor is placed between +ve and -ve rails to smooth the rectified current.
Using the analogy of the balloon teed into a water pipe, that that is turned off and on at regular intervals - If the capacitor's capacitance is not high enough, then it will not store enough charge to supply the same current (compared to the the 2200uf capacitors) when the rectified wave is in the vicinity of a trough.

Can you, or someone else, briefly explain how a lower ESR justifies using a significantly lower capacitance replacement. (say, from 2200uf to 1200uf)
i.e. where do you draw the line - why not 600uf?

I'm educatedly guessing that a lower ESR (for a capacitor) means that the charge that is held by the capacitor faces less restriction by the capacitor as it is being released?
So therefore, for the 2200uf capacitor to be replaced by one of a lower capacitance (and lower ESR), it must have had some redundancy (not coming close being completely discharged during each cycle)

If that is the case, then i now understand why.
Amen Ra?

Also, would it be a better choice to use a polymer as a replacement for these capacitors (reliability, lifespan etc)

**Agent24** · 06-19-2014, 11:37 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Originally posted by socketa View Post

And note that rs-online don't readily supply the motherboard caps to plebs (unless you want 600 of them)
Is this some kind of a conspiracy?

Really? The link you showed had Minimum Order Quantity (MOQ) of only 5. I buy capacitors from RS NZ a lot and most are MOQ 5 or 10. If it's something like 600 you are probably trying to buy a whole box\reel\etc.

**socketa** · 06-19-2014, 11:56 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Whoops!
Sorry, that wasn't the link i meant to post. (that's what i get for having 3 browsers, and 30 tabs, open)
At rs-online, i couldn't find any matching aluminium electrolytic replacements for original 6.3v 2200uf 2500mArms caps

The link i was intending to post was this:
http://www.digikey.com.au/product-se...=0&pageSize=25

Anyway, mariushm explained, and i now understand why.
Can we please return to post #7

**c_hegge** · 06-20-2014, 12:50 AM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

As far as appropriate replacements are concerned, The panny FMs you posted in your first link would actually work. The ESR is very slightly higher, but they would be close enough.

Polies like these (http://au.rs-online.com/web/p/alumin...itors/7955673/) would have a theoretically longer lifespan, but they are expensive and, on an older board, the lifespan might not matter than much as either would outlast the rest of the board.

BTW, If you can't revive this board, I'm pretty sure I have a working MSI KT6 Delta just like it which you could have for the cost of shipping.

**socketa** · 06-20-2014, 02:16 AM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

What designates that capacitor (in the link that you provided) as a Polymer capacitor?
So polymer are a better choice, but cost quite a bit more.
Thankyou very much for the offer, but got enough motherboards etc now, to last a few decades, now that i'm becoming more confident that they can be resuscitated.

Could someone give a reply to post #7?
Is my reasoning along the right lines?

**mariushm** · 06-20-2014, 05:59 AM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

yes, capacitance is an important factor, but you have to understand the dc-dc converters work at high frequencies and have multi-phase converters 2+1, 4+1, 6+1 etc so the ripple is very small.

If you work with mains power (110v or 230v and 50-60Hz) you rectify that with a bridge rectifier and you have a dc output with about 100-120 pulses of energy, so you have to smooth that wave out and you need a lot of capacitance depending on how much current you need (approximation for capacitance would be current / ( 2 x AC Frequency x Vripple)

But, on motherboards, you have 12v coming from the power supply which already has about 2200+ uF capacitance to smooth out the ripple. Then, right by the 12v 4 pin connector on the motherboard you have one or several 1200-3300uF 16v capacitors which again act as a bulk storage of energy for the dc-dc converter.
Now you have a dc-dc controller on the motherboard which works with several phases (2+1, 4+1, 6+2, 8+2 etc) ... each phase is formed of a one or several mosfets, an inductor and capacitor.
The controller works at high frequencies 300 kHz, 600kHz, some work even at 1Mhz and basically what they do is turn on mosfets for a brief period of time and then turn the mosfet off.. this can be thousands of times a second or more. The energy that manages to move through the mosfets goes through the inductor and then into the capacitor.
The controller monitors the voltage on the capacitors and adjusts dynamically the turn on and off times of each phase and that's how the voltage remains stable regardless of how much current the processor uses.

When there's several phases, the controller basically (for example) turns on a phase for 2 ms and keeps it for 3ms but 0.5 ms after it turns on the first phase it turns on the second phase and so on. Each phase is slightly delayed from the previous one, to increase the number of pulses of energy that go to the output.
So if a phase turns on 1000 times a second, in a second with 2 phases you'll have 2000 turn on and offs..

So think of whatever is in front of the 6.3v capacitors as a rectified AC voltage that was at thousands of Hz ... instead of just 100-120 big pulses of energy you have thousands smaller ones. So the capacitance needed to smooth those bumps is much smaller. The inductors in front of each capacitor also help a lot - inductors resist current change and for example, if the cpu suddenly pulls a lot of current, some energy from the inductors will go to the cpu until the dc-dc controller increases the turn on time.

-

can you, or someone else, briefly explain how a lower ESR justifies using a significantly lower capacitance replacement. (say, from 2200uf to 1200uf)
i.e. where do you draw the line - why not 600uf?

It doesn't necessarily justifies. The way I understand it (and I may be wrong) .. the esr is .. as the term says .. an internal resistance. You have V = I x R and P = I * I * R .. so if the capacitor has 0.01 ohm esr, and your cpu pulls 1.3v at 10A then you have a potential voltage drop of 0.1v and about 100*0.01 = 1 watt dissipated into the capacitor.
With lower esr you have lower voltage drop which makes it easier to make the output voltage more stable with variations in current, and the capacitors heat less and last longer time.
So paralleling several capacitors reduces this esr, every capacitor heats less, there's more leads and more wider traces to handle those currents etc etc etc

depending on how many phases and how fast the dc-dc controller is on your motherboard, that guides you in choosing the minimum capacitance.. some older intel datasheets/documents were suggesting a minimum of 1000uF capacitance or something like that, but suggested using multiple capacitors for lower esr and longer life (but don't ask me to give you those documents as I don't have them and don't even know what document would that be). Anyway, these were old documents from p4 times, newer processors have different requirements, use less power etc.

--

Also, would it be a better choice to use a polymer as a replacement for these capacitors (reliability, lifespan etc)[/QUOTE]

yes, it would help but for that motherboard it makes no economic sense. They're too expensive. Those Panasonic FR capacitors have 4000-10000h @ 105c so they'll last for years without any problems on such motherboard.

**Dan81** · 06-20-2014, 07:32 AM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Originally posted by mariushm View Post

Those Panasonic FR capacitors have 4000-10000h @ 105c so they'll last for years without any problems on such motherboard.

I know this isn't a solution for OP but....
If a board is populated with only Rubycon and Panasonic caps,does that make it good?

I ask this as my ASUS P4P800-VM has only FJ Pannies next to the CPU socket,and the rest is Rubycon ZL,save for a MBZ between DDR slots and IDE ports and 2 small TEAPO caps next to the audio chip in the upper left corner.
However,ANY other version I've seen on the internet has Chemicon KZE instead of the ZL caps and either OST RLX or KZG caps instead of the Panasonics.

**Agent24** · 06-20-2014, 02:51 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Originally posted by Dan81 View Post

I know this isn't a solution for OP but....
If a board is populated with only Rubycon and Panasonic caps,does that make it good?

I ask this as my ASUS P4P800-VM has only FJ Pannies next to the CPU socket,and the rest is Rubycon ZL,save for a MBZ between DDR slots and IDE ports and 2 small TEAPO caps next to the audio chip in the upper left corner.
However,ANY other version I've seen on the internet has Chemicon KZE instead of the ZL caps and either OST RLX or KZG caps instead of the Panasonics.

If they are genuine ones, then it should be. Of course even the good ones don't last forever, so age is a factor.

Sounds like you may have had one that was already recapped? Check the solder joints on the capacitors, do they look any different to other parts on the board?

**socketa** · 06-20-2014, 08:35 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Very cool, thanks, mariushm!
Thanks for your time and effort.

Have used reference numbers here, 1), 2) etc, to make a reply easier.

Have read and re-read the first section of your post quite a few times now, and a couple of pennies dropped.
You lost me, a bit, when you mentioned "phases (2+1, 4+1, 6+2, 8+2 etc)"
But i sort of get the basic concept of the phasing creating more pumps (less ripple) in-between input cycles.

I also see why the initial pulses from the PSU are 100-120hz. (2 pulses for each AC cycle)

Regarding the formula: ( 2 x AC Frequency x Vripple)
1) How do i find out Vripple? I checked 4 PSU's, and nothing is written on their labels about ripple. Is Vripple the variation in voltage (see my link at the end of this post).

Regarding your comment on low ESR and capacitance.
Let's say the Capacitor was perfect and had no ESR, then the discharge would be completely regulated by the resistance of the circuit.
So lets say, for the existing 2200uf caps, that 2200uf is required because it is above the minimum capacitance required for functional circuit operation, according to the cap's ESR.
A larger cap with the same ESR could be used, but also a smaller one could be used with a lower ESR
Fair enough?
If so,

2) What is the (roughly - speaking) relationship between ESR and required capacitance?
i.e, if it was linear it would be 1/2 ESR = 1/2 capacitance

I note that you said that it was the cap near the 12v 4 pin connector.
3) Is that the one that deals with the output of the PSU and smooths the current to all of the rest of the motherboard?
It is not a "1200-3300uF 16v capacitor", but rather, a 1000uf 6.3v OST capacitor, which is not bulging (i know that that doesn't mean that it is ok)
Did you mean 6.3v, not 16v?
You mentioned a rough minimum requirement being 1000uf, and that's exactly what this cap is.

The caps that i was focusing on were the 6 larger ones, around the CPU.
- a couple of which are not quite flat.
4) What do these capacitors do?
Can i apply the same reasoning for their replacement, as the one at the 12v 4 pin connector.?

Also made a webpage on ripple
5) If someone can check this out to see if it is correct.
http://www.stillflowing.comze.com/capacitor.htm

**Dan81** · 06-21-2014, 07:55 AM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Originally posted by Agent24 View Post

If they are genuine ones, then it should be. Of course even the good ones don't last forever, so age is a factor.

Sounds like you may have had one that was already recapped? Check the solder joints on the capacitors, do they look any different to other parts on the board?

Strangely,it's not recapped at all,because if it was there would be a small resin mark,but there isn't any.All I know is that board originally came from a T-Systems MT40 machine.

**mariushm** · 06-21-2014, 08:27 AM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

I also see why the initial pulses from the PSU are 100-120hz. (2 pulses for each AC cycle)

No.

In a classical power supply like you see in audio amplifiers and other devices, you have a large heavy transformer (either toroidal or the classic EI shape one). Input AC voltage (at 80-250v AC , 45-65 Hz) comes in as a sine wave and comes out through the secondary winding at a lower voltage, still at the same frequency.. 45-65 Hz.
Then, a bridge rectifier is used to transform this AC sine wave to a DC wave with twice the number of "lobes" or "peaks" that originally. So now you have a DC output with 90-130 pulses a second. Now you have to use capacitors to smooth out this DC output.

A switching power supply (atx power supply etc) works differently.
The input voltage comes and it's right away rectified using a bridge rectifier to DC voltage and then a capacitor is used to smooth out this DC voltage a bit.
So you had 80-250v AC 45-65 Hz and after rectification you have about 110v - 360v DC with pulses at 90-130Hz.
Optionally, the power supply has an active pfc circuit which boosts this dc voltage up to 420-450v DC. Then, you have a capacitor which only has to make sure there's a minimum voltage all the time, for example let's say 150v DC.
So at any time, the power supply has an input voltage of 150v-450v DC.
Now, there's a controller inside the power supply which sends pulses of energy from this DC input through a high frequency transformer, the controller basically creates a square wave that goes through the transformer and on the secondary winding you have 12v or 5v or other voltages.
By varying the number of pulses and the duration of the pulses, the controller manages to produce at the output of this transformer a relatively stable voltage.
But unlike the classical power supplies, the controller works at high frequency, potentially up to 300-600 kHz, so that's why the transformer inside a computer power supply is so much smaller and lighter, and that's why you need smaller capacitors and so on. You're not working with 60-120 Hz anymore, you're working with thousands of Hz and with square waves, not sine waves.

So the formula that I mentioned above which approximates the capacitance required, it's only valid for the classic power supplies, using big heavy transformers that work with sine waves and low frequencies. It may be "good enough" for up to 400-600 Hz but by no means is it valid for switching power supplies.

So your questions at 1) and 2) makes no sense in the realm of switching power supplies. The ripple of the voltage is dependent on how well the controller reacts at sudden demands of current from components (to change the number and duration of pulses going through the high frequency transformer) and it also varies with the filtering implemented on the output. Lots of power supplies use a classic PI filter ( capacitor - inductor - capacitor) to smooth out the output and make the voltage vary less. Changing the inductor value (and/or its specs) in that filter can make just as much improvement as changing one of those two capacitors in the pi filter, for example.

Now back to your board. Here's a better image I took from google images:

And here's the schematic of your motherboard - note that it may not be the same as your exact board, it may be a different revision, but it's close enough:

http://savedonthe.net/download/561/m...v_100_sch.html

PDF should also be attached below.

If you go on page 39 in the PDF, you'll see the voltage regulator module. You see there voltage coming from VCC (the 4pin 12v connector) and then it goes through an inductor which is the one to the right of the 12pin connector. Then, it goes through several tiny surface mount capacitors and some capacitors that in the schematic show up as 1500uF 16v. The schematic shows 3 but your board could have only 2 x 2200uF or some other values. The capacitors I talk about should be the ones above that inductor, a bit to the right of the speaker jacks and the 4pin 12v connector.
From there, the electricity goes through at least 4 of those black squares with two leads coming out of them (those are mosfets). The schematic shows two phases, each phase having two mosfets.
Each phases' output goes through a choke/inductor (those coils to the right of the mosfets) and then the voltage goes out to capacitors to smooth out the voltage further.

If you check the pdf datasheet, you can see that there's a LOT of capacitors on the output of the regulator - you have there one phase with 2x2200uF+1800uF, one with 3x2200uF and another one with 3x2200uF. The schematic is ideal, it's more than needed, hence why the version of your motherboard only has 3 capacitors installed out of four locations above the processor socket (in my picture) and 2 capacitors to the left of the socket (in my picture) which I believe it's not related to the power going to the cpu, it's more likely to be filtering for the chipset (hence why it's smaller at 1000uF on your board, as chipset doesn't use a lot of power)

And if you're curious, the HIP6302 dc-dc controller and the two phase controllers/drivers HIP6602 (or whatever is used on your version of the motherboard) should be those tiny chips above the capacitors near the connectors, or in top right corner of the motherboard in my picture.

So you have some capacitors rated for 16v at the input, near that 12v 4pin cpu power connector. Those are the bulk storage for the dc-dc converter. dc-dc converter sends pulses of power through those mosfets and you have smaller voltage on those 6.3v rated capacitors after it goes through those chokes/inductors.
The 16v capacitors are needed for moments when the cpu suddenly demands lots of power, for example when it goes from 10w idle to 60w load in a game. The controller has to pull more current all of the sudden, the power supply has to react to this sudden demand and ramps up in a few microseconds or milliseconds, those 16v capacitors are there to provide instant energy until everything recovers or goes up to the new demand.
There's also other technical reasons why those capacitors are needed but the post is long enough already.

If you want to learn more about phases and how dc-dc converters work on motherboards, these videos are VERY informative:

Motherboard VRM Explanation Part1: The VRM and PWM : https://www.youtube.com/watch?v=zDxFbAhu4Bo

Motherboard VRM Explanation Part 2: Digital vs Analog PWM : https://www.youtube.com/watch?v=Viitg4Yoy2Y

Attached Files

**pfrcom** · 06-21-2014, 07:40 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Originally posted by Topcat View Post

No, that's the datecode. The cap was made the 38th week of 2003.

Here's a good replacement for those:
https://www.badcaps.net/store/produc...roducts_id=137

I do ship to Australia.

https://www.badcaps.net/forum/showthread.php?t=13260

**socketa** · 06-22-2014, 05:18 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

Hi Marishum,
Two things were mentioned in your post: dc-dc controller, and dc-dc converter.
Just to be clear about this,
is the dc-dc converter the one in the PSU?
and the controller, the two mosfets (and the driver) on the motherboard?

i watched those two vids, and will be watching them again
woah - blew my tits off!
but i get the basic idea of what is going on, thanks.

Ok,
i was hunting for position C23 and couldn't find it on the board (maybe it's not there since this is rev 2.0?)
And while i was doing that, i noticed an unusual component, then i realized that it was not an unusual component, but rather a burned-out small capacitor)
1. What could have caused this?
i don't see how a partially-shorted 16v cap could cause this - it's not like that would increase the current from the PSU,
so it seems like this is the result of a suspect PSU, not blowing it's fuse when it should.
2. In such an instance, do those tiny caps explode before the big caps?
3. What is the function of these tiny caps that are in parallel with the 16v electrolytic caps, and how necessary are they?
4. Does 475P/0805 mean 475 pF, and what does 0805 represent?
5. Is it possible to solder a new cap on (with tweezers and an electron microscope)?

After cleaning up the burned area and the disintegrated cap,
i turned the board over and tested (+ve to +ve, -ve to -ve) across all the three 12v caps, and got 2/3 FSD on ohms x1
Then tested across the seven 6.3V caps, and got FSD on all of them
On both tests, the needle did not drop back - indicating current flow through all of them
(Had some 470uf lying around and tested on of them, the needle went up and down quite quickly, so the meter seems good)

Looking at the circuit diagram for the 6.3v caps, if one is shorted, and i measure across another good one, then the multimeter current will be going from one side of the cap, through the motherboard earth, through the faulty cap, along the +ve rail to the other side of the good cap (after the cap has charged).
So, it seems that, in this instance, in-line testing can not identify which cap it is, they will have to be removed, one at a time, until the fault disappears.

Here are the Pics:
http://www.stillflowing.comze.com/mo...melted_cap.htm

**Agent24** · 06-22-2014, 05:32 PM

Re: Replacing OST caps on Microstar KT6 Delta motherboard

C154, that ceramic capacitor could have just shorted by itself and burnt out. Or was stressed due to the faulty electrolytic capacitors not filtering the supply properly and shorted out.

470pF sounds right to me. 0805 indicates the size.

Installing a new one would be easy, following this method: https://www.youtube.com/watch?v=qs7rSM731gk

Suggest you practice on an old board first though. But it's actually quite easy once you get the hang of it. And make sure you have good flux.

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Replacing OST caps on Microstar KT6 Delta motherboard

Replacing OST caps on Microstar KT6 Delta motherboard

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