Dell Server PSU Teardown

[blasterboomer]

I opened a Dell Server PSU, what do you think? also arent ltec a bad brand of caps especially for a server...

[Khron]

Re: Dell Server PSU Teardown

Normally, Ltec aren't great, but 1) i've rarely (if ever) seen any of them outside of Delta power supplies, and 2) somehow, Delta manage to pull off some sort of mojo-voodoo by which they make Ltec's last for quite a while

And Newton Power Systems are either a subsidiary, or just a brand, of Delta, so...

[c_hegge]

Re: Dell Server PSU Teardown

Yup. LTECs fail everywhere else, but not in Delta PSUs.

[cheapie]

Re: Dell Server PSU Teardown

I've had Ltecs fail after about a year or so in a Delta power supply from a Lexmark C543dn color laser printer. Most of the caps (Ltec and CapXon) were fine, but two Ltecs under one of the heatsinks on the secondary side were bulged.

[Wester547]

Re: Dell Server PSU Teardown

They were making reference to well ventilated and cooled Delta PSUs. Printer PSUs don't count where the capacitors were touching the finless heatsinks. Neither do LCD monitors; LTEC capacitors will be bloated in those PSUs as well. They run as hot as hell. (note that I am defending DELTA, not LTEC )

[Khron]

Re: Dell Server PSU Teardown

I'm quite sure Delta did their homework regarding those supplies, but i'm willing to bet money the system designers (ie. people/teams who designed the cases / devices those supplies were used in where Ltecs fail) either didn't give two flying f*beep*s, or had no clue about, cooling requirements and such...

[CapSwapper]

Re: Dell Server PSU Teardown

Ltecs are garbage. take one out and measure it and its probably way off. I would yank them all

[Behemot]

Re: Dell Server PSU Teardown

They were making reference to well ventilated and cooled Delta PSUs. Printer PSUs don't count where the capacitors were touching the finless heatsinks. Neither do LCD monitors; LTEC capacitors will be bloated in those PSUs as well. They run as hot as hell. (note that I am defending DELTA, not LTEC )

It's Delta stupidity to use them in such conditions so the blame goes back to Delta. One of the worst Deltas I've ever seen:

Also the Delta GPS-x00AB platform is quite troubled with bloated caps.

[stj]

Re: Dell Server PSU Teardown

the heatsink is too damned small and the component is probably underated.
i wont blame the caps when the board is that burned - it's even burned where the heatsink is soldered down at the left!!!!

[c_hegge]

Re: Dell Server PSU Teardown

Yah. I never really blame the caps itself for failing if the PCB around it is heat darkened. You can cook Rubycons in such conditions.

[Per Hansson]

Re: Dell Server PSU Teardown

I'm not saying you are wrong but keep in mind as the cap fails the switching transistors need to work _much_ harder to keep a stable voltage output.
Thus heating up waay more than normal...

[Behemot]

Re: Dell Server PSU Teardown

This. It was probably pretty hot already and when the caps failed, the silicon burned itself. I got another one (most likely bad signal board), it is not so black but still it was heating as well.

Anyway Delta fucked up heavily. With Chemi-cons KY it would work twice as long at least, but I guess Acer didn't want that lol

[stj]

Re: Dell Server PSU Teardown

i also just realised that the caps would be above the heatsink when it's assembled, so getting cooked by convection too!!!

[Wester547]

Re: Dell Server PSU Teardown

It's Delta stupidity to use them in such conditions so the blame goes back to Delta. One of the worst Deltas I've ever seen:

Also the Delta GPS-x00AB platform is quite troubled with bloated caps.

Look at that, the small Teapos (visibly) outlasted the LTECs.

...

Delta have sometimes been prone to error like any other company. Poor designs in LCD PSUs and using CapXon in GPS-series PSUs aren't their only erroneous decisions. Sometimes they underspec the primary rectification diode in the two transistor +5VSB circuit (using a single standard recovery rectifier diode I think, something like IN400x) and it gets so hot (without airflow that is) as to even kill the "critical" Japanese capacitor in their older PSUs (DPS-300KB-1x, DPS-85NB, and some other PSUs come to mind) since they had a habit of placing the capacitor right next to that diode. IIRC everell had to repair the snubber circuit in another Delta PSU because it too was underspec'd and failed. And the GPS-300AB-100V series of PSUs always has the +5VSB output diode running way too hot and cooking the output capacitor present (usually a CapXon GL since it was right next to it), probably because they only used a 3A diode or something without a heatsink (the same way Bestec PSUs run too hot in terms of +5VSB output rectifiers). This is a stark contrast to other Delta PSUs that use a single, low VF 10A/40V TO-220 rectifier on a finless heatsink for +5VSB rectification...

HOWEVER, with regard to their well ventilated PSUs with ample airflow, generally speaking, capacitor failures are rare in their PSUs unless we're talking CapXon. This is especially true if you compare the amount of LTEC failures in Delta PSUs, overall, compared to the amount of Teapo failures in Hipro PSUs and LTEC/OST failures in Lite-on PSUs (on the output - there is no comparison - Teapo capacitors, G-Luxon capacitors, etc, fail all the time in Hipro units....). While Hipro PSUs are designed very well for the most part, the thermal design on the secondary side is not ideal and so the capacitors run hotter and suffer a shorter life. That being said, Hipro PSUs are very solid with a recap...

[c_hegge]

Re: Dell Server PSU Teardown

And the GPS-300AB-100V series of PSUs always has the +5VSB output diode running way too hot and cooking the output capacitor present (usually a CapXon GL since it was right next to it), probably because they only used a 3A diode or something without a heatsink

Yup. I have a GPS-300AB in my stash, and the 5vsb diode discolours the PCB. My solution was to take a 12A fast recovery rectifier from the 12V rail of a gutless wonder, screw it to the secondary heatsink, and connect it with wires to where the original diode went. That way, it won't cook the cap.

[RJARRRPCGP]

Re: Dell Server PSU Teardown

Ltecs are garbage. take one out and measure it and its probably way off.

Not as likely as "KM"s. Replace all "KM"s on sight!!

Looks like LCD monitor makers like using KM caps.

[c_hegge]

Re: Dell Server PSU Teardown

^
Do you mean CapXon KM? Definitely replace those.

Ltecs are garbage. take one out and measure it and its probably way off. I would yank them all

They are probably all fine. As I said, they fail everywhere -except- on most Delta PSUs, where they usually hold up just as well as Japanese caps. Delta really do seem to have a way with LTEC.