Dell Z930P-00 Power Supply recapping

[duruk]

Hi All,

Long time occasional reader - first time poster here.

Need help from community to revive (recap) Dell Z930P-00 Power Supply.

/Prehistory.
Dell Server was shut down about three month ago and according to reports, both Power Supplies were (presumably) fine.

Attempt to restart Server about two days ago was unsuccessful: one Power Supply had no lights (Line, Trouble, Active) at all and the other had only Line light flickering repeatedly.

Disassembly of both Power Supplies showed heavy dust buildup, which was removed with long bristle brush and compressed air.

After cleanup, one Power supply still dead (no any lights or relay sounds) and the other has steady Line light, steady Trouble light and little relay engages.
Close inspection revealed aging/bulging capacitors at the output stage in both units./

As original caps are obsolete and no longer available, day worth of on-line searching for suitable replacements lead to nowhere...

So, asking help from community for advice of close equivalents to the following caps below.
Ideally, from Digi-Key or Mouser stock.

Each Power Supply has:
Rubycon MBZ 105° 1800uf/16V - 3ea. - 10mm/23mm - need new ones.
Rubycon YXG 105° 100uf/25V - 2ea. - 6.3mm/11mm - not sure, most likely OK.
UCC KZG 105° 2200uf/10V - 3ea. - 10mm/25mm - bulging tops, definitely need new ones.
UCC KMQ 105° 330uf/450V - 1ea. - 25mm/52mm - most likely OK.
UCC KMQ 105° 270uf/450v - 1ea. - 25mm/42mm - most likely OK.

Am I on the right track to replace only 1800uf/16V and 2200uf/10V caps to start with?

Please see attached and advise.

Thank you!

[Per Hansson]

Re: Dell Z930P-00 Power Supply recapping

Welcome to Badcaps!
Unless the Rubycon MBZ caps look different in one of the PSU's than in your pictures or you know for a fact they are bad you can probably leave them.
If so then only the United Chemi-Con KZG caps need to be replaced.
Usually a 10v cap will be for a 5v rail, then substitution with 6.3v is ok.
(But it needs to be verified with a multimeter of course).

Rubycon ZLH series might work, but ESR is 0.020 vs 0.010Ω of the old KZG which could create problems:
https://www.badcaps.net/store/produc...cm48d9fml9kes7

Lowest ESR rated caps on Mouser only go down to 0.017Ω:
https://eu.mouser.com/Passive-Compon...z0t6dlZ1z0wfbt

They are being replaced by solid polymer caps in manufacturing, basically all ultra low ESR capacitor types like Rubycon MBZ no longer exist in electrolytic form.
Here is a good replacement for the KZG capacitor if you want to go solid polymer:
https://eu.mouser.com/ProductDetail/...JxNYAb9g%3D%3D

[stj]

Re: Dell Z930P-00 Power Supply recapping

in the 2nd picture with the overall image, there is a dark red polypropylene or polyester cap on the lower-right of the board that looks like it may have a hole burned into the top

[sam_sam_sam]

Re: Dell Z930P-00 Power Supply recapping

It look to like this might be a hole as well

[duruk]

Re: Dell Z930P-00 Power Supply recapping

Welcome to Badcaps!
Unless the Rubycon MBZ caps look different in one of the PSU's than in your pictures or you know for a fact they are bad you can probably leave them.
If so then only the United Chemi-Con KZG caps need to be replaced.
Usually a 10v cap will be for a 5v rail, then substitution with 6.3v is ok.
(But it needs to be verified with a multimeter of course).

I was a bit too quick to state it is the same caps on both boards…
In fact, second board has all Rubycon caps, see attached.
Except may be one, they do not look as bad as on the first board.
But this is the board (second), that has a “no start” condition – no any status lights active when line cord is connected.

Also, this specific Power Supply does not have 5V rail, only 12V and 3.3V
See pinout here:
https://www.incredigeek.com/home/tur...-server-a930p/

They are being replaced by solid polymer caps in manufacturing, basically all ultra low ESR capacitor types like Rubycon MBZ no longer exist in electrolytic form.
Here is a good replacement for the KZG capacitor if you want to go solid polymer:
https://eu.mouser.com/ProductDetail/...JxNYAb9g%3D%3D

If I go with above and use 1800uf/16V and 2200uf/16V as a replacements (see highlights in the attached .PDF), will this circuit remain stable?
What I am asking if “super low ESR” and “higher ripple” rating (in comparison with originals) will induce some negative effect on the circuit design, like oscillation?
* I may be completely off here… Although I do understand general concept of “low ESR” and “high ripple current”, I am not much versed when this is desirable and when is not. From what I have read, sometimes “too low” is too much.

[duruk]

Re: Dell Z930P-00 Power Supply recapping

in the 2nd picture with the overall image, there is a dark red polypropylene or polyester cap on the lower-right of the board that looks like it may have a hole burned into the top

It look to like this might be a hole as well

Sorry my bad, should have taken a better pictures.

No, there is no hole in this cap.
It is a small dab of that white compound used all over the board.
See attached.

Thank you for your help!

[Per Hansson]

Re: Dell Z930P-00 Power Supply recapping

If I go with above and use 1800uf/16V and 2200uf/16V as a replacements (see highlights in the attached .PDF), will this circuit remain stable?
What I am asking if “super low ESR” and “higher ripple” rating (in comparison with originals) will induce some negative effect on the circuit design, like oscillation?
* I may be completely off here… Although I do understand general concept of “low ESR” and “high ripple current”, I am not much versed when this is desirable and when is not. From what I have read, sometimes “too low” is too much.

Yes it should be fine, originals are 0.012Ω ESR and new caps 0.08Ω
Higher ripple handling capability is always a good thing, only ESR must remain as close as possible to the originals...
BUT: if the supply is dead and the caps look as nice as they do that is highly unlikely to be the problem.
Check if you have between 325VDC > 400VDC on the primary bulk capacitor to begin with.
(And understand that with such high voltages extreme care must be taken!).
As a start I would replace this first: "Rubycon YXG 105° 100uf/25V"