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cwailes · Jan 23, 2011, 07:11 PM

Does anyone have a hi-resolution photo of a Mac Pro Dual 2.66 Logic board? My computer has gone down and I have taken it to an apple store and they have narrowed it down to either the logic board or processors. They don't have the parts in stock so they would have to order them. I want to look at a hi-resolution photo of a good logic board (can't fine one on-line) so that I can zoom into different areas and see if mine looks the same. I have one capacitor that looks iffy but not sure, so I want to compare it to a good logic board.

seanc · Jan 23, 2011, 07:16 PM

Can you post a clear focused picture of the logic board & capacitor here please?
Please also post any letters/numbers on it.

Oisín · 07:41 PM

I’ve got one …

But which one is the logic board exactly? I’m not much of a modder, so I haven’t played around with my MP’s intestines, and I’ve no idea which of the boards in the machine is the right one.

(It’s the one I’m writing from—can you get to take pictures of the board without pulling it out?)

Edit: Oh. It’s the big one that runs along the side of the tower, on the opposite side of where you pop open the case, right? That one might be hard to get a picture of …

AKcrab · Jan 23, 2011, 08:01 PM

Yeah, you would need to remove some parts to get a clear picture of the whole board.

cwailes · Jan 24, 2011, 01:56 AM

What has happened is that about two weeks ago, my screen saver was frozen. I powered down the mac pro from the power button and then restarted the machine. It failed to boot completely up. It got through the apple logo and then went to a gray screen. I did this about 15 times. I have done everything that I know how and could not get it to boot. I have always been able to fix my own computers, but this was a first. I broke down and took it to an apple store. They ended up having to trouble shoot it part by part and have narrowed it down to the logic board or one of the processors. Me, wanting to try to figure it out myself, took it apart enough so I could see the entire board. I found one capacitor that I questioned. It is a "solid-cap" capacitor that is behind the memory bays. All of the "solid-cap" capacitors that are around it are smooth, but this one in particular is not and has a "K" bulge coming from the inside. That lead me to believe that it has gone bad. However, I want to get a look at a good logic board to see if that particular capacitor is the same.

reader50 · 02:14 AM

Does it look like these electrolytic capacitors? If it does, a bulged top means it is bad. An improper chemical reaction has taken place inside, which will result in failure. Either immediately, or shortly.

cwailes · Jan 24, 2011, 02:36 AM

No, it is a "Solid Cap" meaning it is completely encased in aluminum. It looks like

http://www.manufacturer.com/cimages/..._Capacitor.jpg

just not this exact one.

Waragainstsleep · Jan 24, 2011, 07:49 AM

They ought to be able to run this unit on one CPU if memory serves.

cwailes · Jan 24, 2011, 10:52 AM

So you are saying I could take one processor out and it should boot? So I could then locate which one is bad?Won't this cause possibly more damage running on only one processor?

Waragainstsleep · Jan 24, 2011, 12:32 PM

If its not supported, it just won't boot I suspect, Be careful handling the CPUs. As well as the usual ESD precautions, Apple uses some fairly nasty substances for thermal transfer which you do not want to remove from the chips. Keep the heat sinks matched to the CPUs as some of this goo will undoubtedly stick to them as well.

I honestly can't recall if this works or not. The service manual doesn't actually mention it explicitly. But then they didn't always. Perhaps someone who still has access to SPS would be kind enough to give them a shout and ask them if you are still in doubt.

Personally I think you are probably onto something with the cap. These CPUs don't go bad very often. There are some images of the caps in the service manual if you can find a copy anywhere. Not brilliantly high res but probably good enough in a pinch.

There are some caps just about visible in this image:
http://diglloyd.com/diglloyd/blog-im...connectors.jpg

cwailes · Jan 24, 2011, 12:45 PM

the cap that I was looking for is just to the right of the lower right purple one in the picture. If the picture was just a little farther to the right I could see the one in question.

Waragainstsleep · Jan 24, 2011, 01:44 PM

Its tough to make out in much detail in the service manual but it looks the same as the ones in that row to the left of the aforementioned image.

cwailes · Jan 24, 2011, 04:32 PM

I will give all of this a try.

Waragainstsleep · Jan 24, 2011, 06:42 PM

Forgot to mention the thermal compound Apple use is toxic. They issue techs with gloves to handle it.

cwailes · Jan 24, 2011, 07:19 PM

What happens if there is hardly any of that thermal compound on there? Can or should I add any arctic silver compound?

cwailes · Jan 24, 2011, 11:40 PM

Ok, I tried booting it off of each processor separately and it would not boot. Does that mean it is the logic board? Or does that mean mine just does not support booting from one processor?

Waragainstsleep · Jan 25, 2011, 05:14 AM

Probably the latter. I'm sure some of them support this, I guess yours is not one of them. Troubleshooting these units past this point is a pain in the ass. The service manual actually instructs engineers to replace both CPUs at once. Usually not before the logic board though. If only because the logic board is a much cheaper part in Apple's system.

I would work off the assumption that the cap has gone bad. Were you planning on doing a component level repair?

cwailes · 11:48 AM

What I was thinking of doing is having The Apple Store order the logic board. They want $419 for it which is cheaper than I can find on-line. I was then going to replace that and see if it boots. If it does great I am done. If it doesn't then I was going to return the LB to Apple and then order a processor on-line which I found cheaper than what Apple is willing to sell it to me for. What do you think, good idea? Here is a picture of the "Solid Cap" in question.

seanc · Jan 25, 2011, 04:37 PM

That cap is visually fine. Unless you're going to take it out of circuit and verify capacitance and ESR, lets assume the issue lies somewhere else.

Waragainstsleep · Jan 25, 2011, 08:04 PM

Looks ok to me too.

Waragainstsleep · Jan 26, 2011, 06:55 AM

Its worth pointing out that the Quad-core chips drop straight into these units if you fancy trying an upgrade.

cgc · Jan 26, 2011, 06:07 PM

Originally Posted by Waragainstsleep

Its worth pointing out that the Quad-core chips drop straight into these units if you fancy trying an upgrade.

Those quad-core Xeons are crazy expensive...I've only seen them listed as low as $650 each.

Waragainstsleep · Jan 26, 2011, 07:23 PM

You should see Apple's prices for them.