2006 mac pro (A1186) 2.66GHz - only one diagnostic led on: LED 1 (trickle power)

[mpinho]

Hello,

This is my first post, so I'd like to start by thanking all the advices I could find.

So... I bought a 2006 Mac Pro last week and it does not boot.

Symptom: "Power-on LED illuminates when power button is pressed and fans spin continuously but there is no boot tone or video".

Yesterday, I found one tip for troubleshooting: measurement of the Optical Drive "Molex" power connector.

According to the tip, measurements should be 12V and 5V.

But I have 12V (12.6) and 26.6V. This second value is really concerning me.

I'd guess that the PSU is damaged. What do you think?

And with a value so high, should I expect everything along the board to be fried?

Thank you so much in advance,

mpinho

 

[harryb2448]

G'day and welcome to the forums.

I think you are on the right track about a dogey power supply. That is the only problem I had with that model Mac Pro. Suggest contacting the seller abd seeking money back, or if no go asking if the PS had been changed, and was the correct PS fitted. There was a hack around in about 2009 using ASX PS I think the brand was. It certainly is not working and meeting the specifications you paid for.

 

[mpinho]

Thank you for your reply.
I can't return it, so I'll try to fix it.
What about further damages? Do you think they are likely?
Kind regards,
mpinho

 

[harryb2448]

First up I would disconnect from the power. I take it you are not using a surge protector/power board? If so try without the board. Then lay down and remove the side, giving access to the interior. Give it a good clean out, cleaning everything you can take out, hard drives, memory, graphics card etc and I then used an Electrolux vacuum cleaner on blow option and get in then and give it to the Mac Pro. The Electrolux had an advantage in that it had a rubber 'sticky beak' and could not short anything out. You may be quite amazed at the dirt that comes out. Replace everything, ensuring the memory modules and graphics card are firmly seated, and if possible with another power cord, re-connect and try to boot. Keep us posted mpinho?

 

[mpinho]

Hello,

By "surge protector/power board", do you mean something like this?

If so, this is the model which I'm using.

I already gave it a good clean. At this moment, I believe I just did not take apart the CPU's heatsinks. Everything else is pretty much clean.

Later today, I'll buy another power cord.

Thank you.

mpinho

 

[mpinho]

Hello, once again.

I've been thinking, since the power for the optical drive comes from the motherboard, isn't possible that the 26.6V value read on the molex has something to do with the motherboard itself?

Thank you,

mpinho

 

[harryb2448]

Have you tried plugged directly into the mains?

Personally do not trust surge protectors but use a UPS for surge protection, black and brown outs etc.

 

[mpinho]

Hello,

Thank you for your advice.

Just found a bad capacitor inside the PSU - it might be it. I have to find some time to safely replace it.

Thank you,

mpinho

 

[mpinho]

Hello,

I've already taken the capacitor out, but now I'm waiting for a new one - I couldn't find one with the same specifications so I had to order it.

I'll post the "result" as soon as possible.

Thank you,

mpinho

 

[mpinho]

Hello,

I replaced the capacitor but the value read in the Optical Drive "Molex" is still no good - it has changed but still no good. It should be 5v but it's 16.4v.

harryb2448 as you suggested, I've also tried to plug it directly into the mains, but it didn't work

Thank you,

mpinho

 

[mpinho]

Hello,

Since I had the PSU out of the chassis, I decided to measure all the rails.

Conclusion:

Only one 5V rail is outputting a wrong value, all the others seem to be just fine.
The "bad rail" is the one found on the PSU's J4 Molex under PS_on.