Dell GX620

[midibob]

Hi all,

As yet I'm not sure this is a bad cap issue so I'd be interested in hearing anyone's experiences.
My son works in IT and has told me that a large number of GX620 mobos are starting to fail at his workplace, sometimes visibly ie C329 (next to the cmos battery) is venting (820uF).
I have only seen one failed board so far which doesn't show any signs of distress. The ESR of the caps, in circuit, looks OK of the 820 and larger ones that I've checked so far.
The new replacement boards are fitted with Rubycons throughout. Another one I have seen had a mixture, the 820uF were brown and un-named?
The faulty one I'm looking at has Nichicon for the 820uF and the rest Rubycon. The Nichicons all test 0.1 ESR in circuit.

I'm hoping to lay my hands on one of the vented ones when the next one fails (I'm sure that won't be long).
Searching the web there's not too much about these but I do get the feeling that it's going to be an upcoming issue. The 3 year guarantee has just run out too so it's looking a bit like the old 270 issue.

So, if anyone's got similar experiences I'd be interested to hear.

Bob

[4tified]

I haven't repaired any GX620 motherboards yet, but I will say that the issues are very similar to those of the SX280's, which I've fixed dozens of. Usually only 2 caps go bad on the GX620's upon total failure.... the capacitor you mentioned, and also a 2200uf, 6.3v located right underneath the hard drive. Not alot to say about replacement except to make sure you replace all the 820uf and 2200uf caps of the same brand on the board, because once you replace those two that failed originally, the rest are sure to follow within 3-4 month, if you're lucky.

Good luck on repairs, it should only take 5-10 minutes if you have the resources.

[midibob]

Thanks for the reply,

Interesting that the 2200uF are Rubycons. I was thinking if they were were Nichicons perhaps some fakes had crept in. I've been stung with fake semis in the past and with all those dodgy caps that were made it wouldn't surprise me if somebody had decided to change the plastic covers. Unlikely I guess but who knows.
I was thinking about changing out the whole lot of 820uF and above caps just in case but I'm still suspicious that they should fail after only 3 years. At 105c rating I've seen caps last a lot longer in much more hostile environments.

Bob

[bgavin]

Perhaps there is a run of defective PSU in those machines?

Might be worth a half hour to pull the PSU and lift the cover to take a peek. It might not be the board causing the failures.

[midibob]

I'm hoping to get hold of a PSU if only to be able to test any boards that I try to repair. Although up till now it would appear that once the mobos have been swapped out everything is OK. Time will obviously tell.

The board I'm working on at present, I've now removed all the large value caps and they all test OK ESR wise.
The only caps that have an issue I've noticed are the 220uF ones. A few of these have varying ESR readings, one in particular 12ohms whereas some of the 'good' ones are around 0.4. Mind you although these are Rubycons they are only rated at 85c (tut tut Dell)!
I'm not sure there's any value in swapping out the large value ones as their ESR's are very good (low). Maybe there's a regulator failure, I need to look further into this.

Bob

[Topcat]

I havent seen any yet, but I'm sure its a matter of time before I do.

[PCBONEZ]

Looks like badcap.net will soon have a new pet Dell board.

Source:
http://cnet.nytimes.com/desktops/del...tml#msg2590766

Content:

June 3, 2008 08:07
Terrible
0.5/5
I have a lab with 56 of these machines with the super duper small form factor. During the course of the last two weeks, 26 machines have failed with at least blown capacitors on the motherboard. Some have needed CPUs in addition to the motherboards. Some have needed new power blocks, too.

This lab is very cool, with it's own air conditioning. Speed Step protection is on, and the extra cover on the case is off.

For whatever reason(s), these machines fail constantly. If you do the simple math, I have experienced a 46% failure rate. Maintaining this lab has turned into a full-time job in itself and I have never been so frustrated with Dell products in my life.

If you do have to buy this machine, get a 4-year warranty and then extend it to however long you think you might have the machines.

Caveat emptor.

- WoofDoggie

[midibob]

Hi Pcbonez,

I did come across that article in my travels which lead me to think that this one is about to become more widespread. Dell are denying any issues with this board but I wouldn't expect anything less.
When I get my hands on a blown capacitor board hopefully I'll be able to identify the problem.

Topcat, I'm sure that there are many others out there suffering the same issue so this thread should expand somewhat.

Bob

[PCBONEZ]

Yes,
Dell did the same thing when the HN and HM problems first started showing up.
[In their defense with new problems at first no one really knows what's going on.]
-
It's probably simply heat issues with that one.
Small tight case. Possible poor air flow in some areas inside.
-
On the other hand this may be the beginning of yet another plague.
In that case it might be a year or more before the real problem in known.
-

[Topcat]

Originally Posted by PCBONEZ

It's probably simply heat issues with that one.
Small tight case. Possible poor air flow in some areas inside.

True. Heat in these little boxes kills rubycons and panasonics all the time. I see blown pannies and rubies in SX280's on a daily basis. These systems don't breathe well.

[midibob]

I've managed to get hold of another faulty board this time with with 2 blown caps on it. These are both 820uF and as you can see from attached (hopefully) photo they have blown their tops. One is next to the battery and blue link and the other to the left of the spiked ally heat sink.

Interesting thing is the caps next to them are 220uF and showing no signs of distress, but only 85c rated. These will need checking of course but how much internal heat would the 820's be generating to blow like that. I'm not convinced (yet) that this is caused by external heating alone.
Still, early days yet I suppose.

Bob

[Topcat]

Originally Posted by midibob

I've managed to get hold of another faulty board this time with with 2 blown caps on it. These are both 820uF and as you can see from attached (hopefully) photo they have blown their tops. One is next to the battery and blue link and the other to the left of the spiked ally heat sink.

Interesting thing is the caps next to them are 220uF and showing no signs of distress, but only 85c rated. These will need checking of course but how much internal heat would the 820's be generating to blow like that. I'm not convinced (yet) that this is caused by external heating alone.
Still, early days yet I suppose.

Bob

Replace everything on that board 820 and up. They're all Nichicon's. The blown 820uF's are rubycon. not uncommon for rubycons or panasonics to blow on these boards, they overheat.

[midibob]

Hi all,

Well I have to start with a loud shout of 'Geronimo' as I now have a working board.
What I've found is the 220uF caps were all going low capacitance and only being rated at 85c I'm not surprised. The ones around the outside of the board were not too bad (0.7) but the middle ones varied from ESR's of open circuit, 70, 40, 12 ohms etc. I therefore decided to replace all of them with 105c.
I replaced the two vented 820uF and out of interest they measured around 6 ohms.
All the other caps were still measuring 0.1 so for now I've decided to leave them and see how it goes. Possibly short sighted I know but checking two boards now it appears they don't suffer the same stress.

Anyway, I must give a big, big thanks to Joe (Big Pope) for sending me the caps so quickly.

As for Dell fitting 85c caps in these boards is no more than built in obsolescence and these will probably be failing in huge numbers pretty soon.
I feel a recall coming on

Thanks to all
Bob

[PCBONEZ]

The 220uF probably don't do much filtering compared to the 820's.
In fact probably aren't filter caps at all but are for coupling or something.

Recommend replacing 820's with some that handle more ripple.
The ripple capacity (kinda, sorta) tells you how much internally generated heat they can handle. More is better.

.

[kc8adu]

that board will be a good test of the samxon caps.
i am convinced that nothing short of polys will last in dell gx/sx boxes.
i just curbshopped a 280 yesterday.panasonic fj and fl blown up.
its going full poly tonight if i feel up to it.
hope you can keep that 620 to monitor the samxons.
for a fair test finish the recap as tc said.

[midibob]

I'm keeping a database of the serial numbers as I do them with the caps that were changed. Being as the boards are now 3 years old it's doubtful the PC's will be kept for more than another two years so if they last that long then it's not a problem.
I'll certainly report back here if there's any news.

Bob

[midibob]

A quick update on the 620's.

The failed boards are still trickling in and the common fault in almost all cases bar one is the two 820uF venting (under the disk drive) and all the 220uF around the same area and close to the regulators.
Interestingly enough the odd one I've just repaired, the usual two 820uF tested fine and the failure was due to the numerous 220uF caps going bad. Something to watch out for I think as one usually goes straight for the high value caps.

All the other caps on the board were tested and proved to be at 0.01 ohms. I did change the 820's just in case but it's odd why these haven't failed in this particular board?
I'm expecting another load of faulty boards today so I'll check the date stamps on the caps to see if anything there shows up.

I've also got a load of GX280's to repair but that's for another thread I think.

Happy New Year to all and have a good re-capping 2009

Bob

[lightingguy32]

What form factor are those GX620 machines? I work as a volunteer computer tech for both a local university (which has hundreds of GX620s all mini tower) and my high school (which has about 200 some GX620 desktop form factor machines)

[midibob]

Hi,

I believe these are the USFF type as they have the external PSU brick.

Out of interest they are still trickling in and almost all with the same caps going bad. No repaired ones have bounced yet, touch wood, but lets see what summertime brings.

I find it strange that at the failure rate of these boards, there hasn't been more
people here having the same problems?

Bob

[computernut]

New to the forum:
I have 7 Dell GX620 USFF computers in the network. They are all just out of warranty. 3 of the 7 have had the caps blow. I have replaced the moboards in all 3 so far. So I have 3 moboards I want to get recaped.
Question Can they be capped without the Processor and memory on the board and be sure they will work? The reason for that is that the computers are in use in a business enviroment.
I have included Pic's of the motherboards and put a red dot on each cap that show signs of leakage and/or bulging. The first two computers would not even start. The last computer would post but hang up and give the message that there was no boot drive.

Thanks
Chet