Apple

I just found this on the sidewalk and, of course, couldn't resist bringing it back home.
It appears to be a Quad 2.5Ghz G5 (if I believe the label on the chassis), but without RAM, HDD, gfx board or side door ! Finding all of this would probably not be too difficult but, for now, I would just like to know if it's still alive or not... I plugged an appropriate power cord (looks to use the same kind as the Onyx2) but, of course, nothing happened... no "click" when I plug the power cord, and no light appears. Of course I get no response from the power switch on the front.
I'm not sure how this machine is supposed to behave, nor what is the "minimum configuration" to get it to turn on (I guess it just needs ram, and it can turn on without gfx or hdd), but hopefully with the help of the apple guys arround here I can probably sort it out.
ps : it's not shown on the pictures, but I have the various fans that goes in.

That looks like the water cooled one so it could have had a leak and killed the power supply.

I'm affraid you could be right ! But I'm still wondering if it's worth attempting a rescue...

There are plenty of webpages describing repair of that system. I think I read one (with the poor help of google or someone's translator) in french.

The damage from a leak would be the mainboard though, not the powersupply. Though it sounds like the powersupply might have failed. I think there should be a LED somewhere on the board to indicate standby power.

From the picture it doesn't look like there's residue on the bottom of the case though. If there is a leak it probably can be cleaned up and repaired.

japes wrote: There are plenty of webpages describing repair of that system. I think I read one (with the poor help of google or someone's translator) in french.

Thank you, I will dig in that direction...

japes wrote: The damage from a leak would be the mainboard though, not the powersupply. Though it sounds like the powersupply might have failed. I think there should be a LED somewhere on the board to indicate standby power.

From the little I read, it looks like leaks can damage either psu, mainboard, or both. I guess it's better if the psu is the victim...

japes wrote: From the picture it doesn't look like there's residue on the bottom of the case though. If there is a leak it probably can be cleaned up and repaired.

I examined the system a bit more, and I cannot find any leak evidence... everything looks clean, I cannot find any residue. The only suspect thing is the curled plastic stuff in the bottom of the case. But even, this thing should contain any liquid that would drop on it, plus the absorbing material over. It would need a major leak to kill the psu or mainboard, I guess...

japes wrote: The damage from a leak would be the mainboard though, not the powersupply. Though it sounds like the powersupply might have failed. I think there should be a LED somewhere on the board to indicate standby power.

From the picture it doesn't look like there's residue on the bottom of the case though. If there is a leak it probably can be cleaned up and repaired.

I had a dual G5 fail due to a leak in the cooling system. The power supply in the G5s sits underneath of the processors. The leak in my system affected the Powersupply and not the mainboard, probably due to gravity being what it is... Alas AppleCare replaced the whole system.

Also, the liquid cooling system and the processors are one monolithic package. Meaning, you have to replace/exchange the whole processor/cooling module. You could service it, if you are brave, but it did not seem (when I inspected it) that Delphi had in mind small repairs to the system when they designed the cooling That was for the dual 2.5Ghz G5 model, I have no clue if that is the same case with the quad G5 module.

Edit: looking at the pictures, it seems some of the system fan trays are missing. Did you remove them to take the pictures? If so, disregard this comment. But if you did not, the G5 will not boot or even turn on sans all the system fans present.

hmmm, I forgot the g5 power supply was at the bottom. I've only been looking at the MacPro which has the cpus on the bottom.

I'm pretty sure it won't run without the side door or possibly just the plastic sheet that is supposed to sit inside the door. Running it open would disrupt proper airflow and cooling.

.tsooJ

OK, I have some news here.
I took some time today to remove the cooling / cpu assembly, and extract the psu.
My first impression was confirmed, there was no leak (as you can see on the pics, everything is clean in), but it looks like the psu died by "natural" reasons. There is a part inside that looks burned, but my knowledge is very poor about this...
I'd like to know the point of view of PSU experts here : do you think it can be repaired ? The quads have a 1KW psu, which is very expensive, unlike the 600W ones (for dual G5) that can be found for a reasonable amount.

Depends a great deal on your experience level. Switchmode PSUs are very touchy about component values, sometimes even to the point of values that aren't readily publicized. Inductors and transformers are very often custom, and many times there's an avalanche effect where one component (often a chopper) fails and takes out a couple of others with it.

If you're lucky (and can get something to compare), the failure will be in a section of the PSU that is the same in both the KW and the .7KW supplies (i.e. supplies a rail that has the same capacity, and is made by the same company, and shares the same design) so you'll have a set of parts that are known good to transplant (it's really difficult to figure out what a blown SOT is, I'm trying to figure it out right now. Fortunately my PSU has dual sections with the same design - but it's still no walk in the park).

The bad news is that it looks like an inductor or transformer might be blown. While PSU makers will sometimes/often skimp -erm "ensure economy and value by not using excessively rated parts" on the ratings for capacitors, actives and resistors, I've yet to see a SMPSU where they skimped on the inductive parts. I haven't looked at the latest "1KW PSU for your PC for only $50" type ones, though. Before you despair, look around for any other possibles for the failed component.

It wouldn't look as nice, but could you hack in a sufficiently powerful "PC-ish" PSU to confirm operation before getting too involved in fixing the one you have?

After a bit of reading/learning on this, it looks like that what I have here is a blown tantalum capacitor.
I guess it can be replaced easily (I'm ok with my soldering iron as long as the components are not too small), but the point is to figure out :
- What are the specs of the blown component ? I don't think there is any label on it (I have to remove it to be sure), and I don't know if I can measure it with a multimeter (I have a velleman DVM850BL).
- I guess I should also make sure that other components are OK. How can I do this ?

Thank you

Aw man, you found one for free?
I have been wanting a quad G5 for ages!

Anyways, hopefully when the tantalum cap self-destructed it didn't take anything else with it. I saw it happen before with another system but that was also because a few shoddy caps let the surge pass through and kill the northbridge though that was a PC however I have seen badcaps in G5 macs before.

Are you sure that's a tant? It looks like it might be a MOV (metal-oxide varistor - most of the time if you can see the leads extend into the package like that it's a MOV [but what I see as leads could be something else]), and a dead MOV probably means the PSU was exposed to significant overvoltage.

MOVs usually come in herds - look for another one or two. They're almost impossible to test, but you can compare them and get part numbers to search for.

SAQ wrote: Are you sure that's a tant?

Not at all

SAQ wrote: It looks like it might be a MOV (metal-oxide varistor - most of the time if you can see the leads extend into the package like that it's a MOV [but what I see as leads could be something else]), and a dead MOV probably means the PSU was exposed to significant overvoltage.

MOVs usually come in herds - look for another one or two. They're almost impossible to test, but you can compare them and get part numbers to search for.

There is an identical thing just next to it.
If I have time tomorow I'll unsolder these to have a better look at it, but from what I can see there is no label on it... But if they are MOVs, their physical dimension gives their "specification", right ? I also read interesting fire hazard things about these components...

bplaa.yai wrote: There is an identical thing just next to it.
If I have time tomorow I'll unsolder these to have a better look at it, but from what I can see there is no label on it... But if they are MOVs, their physical dimension gives their "specification", right ? I also read interesting fire hazard things about these components...

The dimensions can "kind of" give the spec, a MOV with higher current rating will be larger in diameter, and a MOV with a higher voltage rating will probably (but not necessarily) be thicker. It's not the sort of thing that you can choose a replacement based on, though. MOVs are usually in the first part of the power supply to shunt transient voltages, so you can base your calculations on the line voltage (remember to use 240V for autosensing PSUs). I'd expect ~300-375V is common, but not having designed or replaced one in a computer PSU it's just a guess.

Which brings me to point 2: Something produced sustained overvoltage, and the MOV stopped doing its job (obviously), unless it was a MOV failure where it shorted on. There will be something else knocked out on that PSU, almost guaranteed. A quick test would be to remove the bad MOV (the PSUs don't need them to run) and try it out, but don't be surprised if something doesn't work.