Dell Precision 470 Workstation

[Per Hansson]

Re: Dell Precision 470 Workstation

bigcape; If you want you can buy the mainboard from me that I recapped in the beginning of this thread, because I don't use it anymore
It is a version (as you can see) with no Poly caps near the CPU VRM

That version does not support the dual core Xeon processor, which I wanted to use.
So I bought a later revision of the mainboard, that comes standard with Poly caps... Works great...

If you still want to recap your with Polys I can open up my system and take a look what Poly caps it uses

But it is strange yours would kill the Rubycon capacitors, the reason mine failed was it used the known bad Nichicon HM capacitors
Rubycon should not fail, and the first capacitors to fail should be the ones near the CPU (if they are electrolytic, and not Poly capacitors)
On your board you seem to imply that the input VRM caps have failed, that would sound to me that the reason is your powersupply is faulty
Genuine Rubycon capacitors should not fail on this mainboard (It could also be that your capacitors are not genuine Rubycon capacitors, it is very hard to make out on your photo, the colors look all wrong but that could be to the way you took the photo aswell)

[Per Hansson]

Re: Dell Precision 470 Workstation

Just reread your post again, to clarify;
The input capacitors that sits in the input of the CPU VRM should not be replaced by poly capacitors, only the ones that sits on the CPU VRM's output should be poly capacitors

Please try to take some better pictures of your actual board so we can get a better understanding of what is wrong, and it wont hurt to open up the powersupply aswell, so long you make sure it has been discharged so you don't kill yourself by the voltages present inside!

[PCBONEZ]

Re: Dell Precision 470 Workstation

Thanks Per Hansson ,,, That's two votes the check the PSU.
Anyone else?
Anyone?
Anyone?

[ratdude747]

Re: Dell Precision 470 Workstation

i see the board was already poly modded... didn't know...

[Per Hansson]

Re: Dell Precision 470 Workstation

i see the board was already poly modded... didn't know...

That was a picture just taken off the web, not of the actual board

[PCBONEZ]

Re: Dell Precision 470 Workstation

That was a picture just taken off the web, not of the actual board

What he said.

That's why the post said: "The photo is one that has been poly'ed."

[bigcape]

Re: Dell Precision 470 Workstation

We repair broken things.
We talk about what shows up here broken.

I get it! I LIKE it too!

Fixing broke things is fun even if costs more in the end. Just some of the equipment I've ended up buying to fix a 5 dollar analog meter ended up costig me A WHOLE WORKSHOP and a new hobby.

Hell just a few weeks ago I set up a darkroom and so far have only had the time to make ONE print! (came out purdy good too!)

Look at my signature pic.... Thats a result of ONE bad harddrive....the rest is "History" as they say, i mean a MESS!


Sean

[bigcape]

Re: Dell Precision 470 Workstation

bigcape; If you want you can buy the mainboard from me that I recapped in the beginning of this thread, because I don't use it anymore
It is a version (as you can see) with no Poly caps near the CPU VRM

That version does not support the dual core Xeon processor, which I wanted to use.
So I bought a later revision of the mainboard, that comes standard with Poly caps... Works great...

If you still want to recap your with Polys I can open up my system and take a look what Poly caps it uses

But it is strange yours would kill the Rubycon capacitors, the reason mine failed was it used the known bad Nichicon HM capacitors
Rubycon should not fail, and the first capacitors to fail should be the ones near the CPU (if they are electrolytic, and not Poly capacitors)
On your board you seem to imply that the input VRM caps have failed, that would sound to me that the reason is your powersupply is faulty
Genuine Rubycon capacitors should not fail on this mainboard (It could also be that your capacitors are not genuine Rubycon capacitors, it is very hard to make out on your photo, the colors look all wrong but that could be to the way you took the photo aswell)

I see that my white ballance was wayyyy off so I retook the shot:
[/IMG]

[bigcape]

Re: Dell Precision 470 Workstation

Just reread your post again, to clarify;
The input capacitors that sits in the input of the CPU VRM should not be replaced by poly capacitors, only the ones that sits on the CPU VRM's output should be poly capacitors

Please try to take some better pictures of your actual board so we can get a better understanding of what is wrong, and it wont hurt to open up the powersupply aswell, so long you make sure it has been discharged so you don't kill yourself by the voltages present inside!

Here is my actual board.


Thank you for all your help!

[ratdude747]

Re: Dell Precision 470 Workstation

it already has polys on it... put some good rubycons or panasonics (or samxons if you are daring) on it...

[bigcape]

Re: Dell Precision 470 Workstation

it already has polys on it... put some good rubycons or panasonics (or samxons if you are daring) on it...

Im guessing the polys are the blue ones?

Why are Samxons "daring", expensive?

[PCBONEZ]

Re: Dell Precision 470 Workstation

Im guessing the polys are the blue ones?

Yes

Why are Samxons "daring", expensive?

Samxons aren't Japanese and some specific series have had problems.
[I think it was GL and [maybe] GS series'. Not too sure on that...]
Some people think they're great and others don't trust them.
- In some sizes using Samxon is the only way to get around the cheap Chinese and Taiwanese caps due to low/no availability of appropriate sized Japaneses caps. For example if you need to replace 3300uF or 4700uF 10mm caps in a PSU and it HAS to be 10mm then Samxon RS 3300uF is about the only option.
.

[c_hegge]

Re: Dell Precision 470 Workstation

I'd give that board a FULL poly-mod. If it gets re-capped in lytics, won't it just happen again, since the busted caps are rubycon?
I think that re-capping a board with busted rubycons in lytics is like replacing bad Fuhjyyu caps with more Fuhjyyu. It would fix it at first, but you would have to recap it again in a year or so.

[bigcape]

Re: Dell Precision 470 Workstation

If my board is already a poly mod or a later production (im going for the latter because the welds are not human!), the other caps's are the reveled Rubycon's...... Then

How do you test if here is a possibility that the VRM chip is damaged because a FET has shorted and therefore Vcore will be too high?

This type of testing and how is new and unexplored by me!

[PCBONEZ]

Re: Dell Precision 470 Workstation

That board isn't known to frequently blow caps outside of the VRM Vcore.
- VRM Vcore is where the polys are in the pic I uploaded.
- That's why Dell changed to polys there.

And, as has been said several times now...
Odds are those caps blew because you had bad cooling or a bad PSU.
If you haven't checked the PSU then you may be running your new board on a PSU that blows caps.

VRM Poly upgrades are easy.

"Full Poly Mods" aren't that simple.
A poorly done full poly mod can lead to an unstable system or even damage the board.
- The rule about reducing uF when you lower ESR does not apply to other parts of a motherboard.
[That rule wasn't 'invented' out of the blue, it comes from a tech doc about VRM's.]
- Some x-mm at x-uF at x-many volts combinations are expensive, hard to find or simply non existent. Poly's max out at about 1800uF/6.3v and 1000/16v. To get higher uF caps you have to go down in volts.
- And you can't cheat on [lower] the volts in other areas of the boards like you can in VRM Vcore because, without physically checking, you don't know the actual circuit volts. You will have to have a working board and actually measure the voltage on each cap with the system loaded and running in each operating condition before you know what voltage replacement caps you can get away with in each position. [Yes, check for every cap.]
-

[bigcape]

Re: Dell Precision 470 Workstation

And, as has been said several times now...
Odds are those caps blew because you had bad cooling or a bad PSU.
If you haven't checked the PSU then you may be running your new board on a PSU that blows caps.

The 470 does not auto shut off if it was caused by bad cooling?

I actualy started by changing the PSU before the blown caps were discovered.

It will be interesting to crack open the OLD PSU!

How do i assure that is not any stored power in it? Are there bleed points where I can short out with a resistor or is it a self beeding PSU?

I never had "operated" on a PSU, just "test n replace"

[bigcape]

Re: Dell Precision 470 Workstation

If you haven't checked the PSU then you may.. (have).a PSU that blows caps.

(bold- bigcape)

Dell's pinouts on their PSU's I've been told are a standard of their own. How would you test the old PSU. I've got it setting right here!

Thx

Sean-Bigcape

[bigcape]

Re: Dell Precision 470 Workstation

I'd give that board a FULL poly-mod. If it gets re-capped in lytics, won't it just happen again, since the busted caps are rubycon?
I think that re-capping a board with busted rubycons in lytics is like replacing bad Fuhjyyu caps with more Fuhjyyu. It would fix it at first, but you would have to recap it again in a year or so.

So where is the lytics to poly conversion chart?

[PCBONEZ]

Re: Dell Precision 470 Workstation

(bold- bigcape)

Dell's pinouts on their PSU's I've been told are a standard of their own. How would you test the old PSU. I've got it setting right here!

Thx

Sean-Bigcape

First crack it open [*with it unplugged] and look for blown caps and/or charred darkened components or PCB.
* With it energized the heat-sinks can be at 2x line voltage or more.

[bigcape]

Re: Dell Precision 470 Workstation

First crack it open [*with it unplugged] and look for blown caps and/or charred darkened components or PCB.
* With it energized the heat-sinks can be at 2x line voltage or more.

I'm GOING in!

A power supply with a handle ought to tell one something all by itself. Especialy in a workstation series!