MP 1,1-5,1 Mac Pro 3.0 A1186 does not turn on, makes clicking sound, LED 5 & 6 flash

[user1647]

Hi folks,

first post, hope you can help me.

Our Mac Pro 3.0 A1186 (early 2008, eight core) which was turned off for a while during Covid, now simply does not turn on anymore.

When pressing the power button, it makes a clicking sound, then 3-4 seconds later another one, and simply nothing happens. No fans spin up, no power light, nothing.

Diagnostic LEDs:
(A) both LED 5 & 6 flash once when the power cable is connected, no other LEDs light up
(B) when the DIAG_ LED button is pressed, only LED 2 (STBY) lights up in yellow, indicating that trickle power is present (quoting the service manual)

what I've tried:
(I) disconnected/removed HDD, GPU, memory boards and all peripherals
(II) did the SMC reset: unplugged power for 15+ secs, reconnect power, wait 5+ secs, press power btn
(III) replaced the PRAM battery (CR2032)

Wanna point out that:
> literally nothing happens when clicking the power btn on the front-panel other than the PSU making a clicking sound, and then 3-4 secs later again
> the diag LEDs 5 & 6 only flash once when I connect the power cable, but NOT when I press the power btn to turn on the machine

My questions:
(1) would this mean that the power supply has failed ? Reading the service manual, this seems to be indicating just that.
(2) prob stupid question, but here we go : is it possible to use 3rd party (non-Apple) power supplies in the Mac ? If so, what would be the required specs ?
(3) any suggestions on where to purchase a replacement PSU ?


Thanks !

 

[user1647]

anybody please ?

 

[OldMacPro2]

I was going to say replace the battery on the motherboard, but sounds like you did.

Must be something with the PS or in the power on circuit.

I’ve seen replacement (used) supplies on eBay. FWIW.

 

[user1647]

@OldMacPro2

thanks for that, so you would suggest to try to replace the PSU first ?

or how could I test the power on circuit ?

 

[OldMacPro2]

I assume you've read and checked the following items in the Service Manual:

1) Diagnostic LED 2 indicates presence of trickle power.

2) LED 2 should be yellow when the DIAG_LED button is pressed.

3) Diagnostic LED 8 indicates that the main power is OK and within regulation.

4) Plug in AC power cord and press the power-on button on the front panel.

5) LED 8 should be green when the DIAG_LED button is pressed, indicating the main power is OK and within regulation.

6) If diagnostic LED 5 and LED 6 are both solidly illuminated at power up, improperly seated power supply cables could be one of the causes. Check all power supply cable connections to ensure they are properly seated.

I would double check all that, before looking for a new supply. Might have missed something the first time through.

And, might even try a new 3 volt battery, or check to make sure the voltage is good, and it's seated properly.

If you double check all that and still no joy, it's probably beyond my ability and experience to help.

Hopefully somebody else on here will see the posts and contribute.

 

[user1647]

re the list:

1) as per OP, LED 2 lights up yellow, indicating trickle power
2) confirmed
3) LED 8 is not lighting up at all
4) nothing happens, other than the two distinct clicks mentioned in the OP
5) LED 8 never lights up
6) as per the OP, both LED 5 & 6 light up red, I've checked all PSU calbles

PRAM battery was replaced two times already, it is seated correctly, unless there is a very special procedure that needs to be done... ?

Thanks !

 

[OldMacPro2]

"5) LED 8 should be green when the DIAG_LED button is pressed, indicating the main power is OK and within regulation."

Based on the fact that LED 8 isn't lighting up, I would say the PS is suspect and probably needs to be replaced.

That's how I am reading the test procedure in the Service Manual.

If you had a spare PS you could swap it and see if that makes LED 8 light up.

 

[OldMacPro2]

"5) LED 8 should be green when the DIAG_LED button is pressed, indicating the main power is OK and within regulation."

Based on the fact that LED 8 isn't lighting up, I would say the PS is suspect and probably needs to be replaced.

That's how I am reading the test procedure in the Service Manual.

If you had a spare PS you could swap it and see if that makes LED 8 light up.

Quick search using DuckDuckGo shows several used supplies at various prices, from ~$50 - $100.

If you live near an independent Mac repair shop, you might be able to find one locally. Otherwise, probably have to order one.

 

[user1647]

Quick search using DuckDuckGo shows several used supplies at various prices, from ~$50 - $100.

If you live near an independent Mac repair shop, you might be able to find one locally. Otherwise, probably have to order one.

unfortunately I don't have a spare one to test, but i found a used PSU on ebay, about to order. The reason why I held back is that after a brief conversation with the seller he said that he does not think it's the PSU (that is the problem).

Naturally, remote diagnosis is always difficult, which is why I started this thread to maybe get some other pointers of what the culprit could be. I guess I'll order that PSU and see if it fixes the problem.

And last question: Is it possible to use 3rd party PSUs in that Mac ? I strongly assume no, but just in case, that would open more options for the replacement part.

Thanks !

 

[OldMacPro2]

unfortunately I don't have a spare one to test, but i found a used PSU on ebay, about to order. The reason why I held back is that after a brief conversation with the seller he said that he does not think it's the PSU (that is the problem).

Naturally, remote diagnosis is always difficult, which is why I started this thread to maybe get some other pointers of what the culprit could be. I guess I'll order that PSU and see if it fixes the problem.

And last question: Is it possible to use 3rd party PSUs in that Mac ? I strongly assume no, but just in case, that would open more options for the replacement part.

Thanks !

I dont have experience with using a third party PS in a MP. You might do some searching on here to see what it takes. My guess is that it’s probably a matter of changing ATX style connectors to the MP specific connectors. I’m sure somebody has done it, if they have multiple GPUs that need a lot of power, but it’s beyond my experience.

 

[bax2003]

 

[user1647]

@bax2003

Hi, thanks for posting, we discussed the various LEDs earlier in the thread. Is there anything you wanted to add ?

 

[OldMacPro2]

Good to have that table for future reference.

There was a Mac Pro for sale locally on Facebook market. It was incomplete, but had a good PS.
Price was very reasonable. You might check that if you want to find one near you.

 

[bax2003]

@bax2003

Hi, thanks for posting, we discussed the various LEDs earlier in the thread. Is there anything you wanted to add ?

Nothing to add, but this is 100% correct info from service manual.

 

[user1647]

just to follow-up:

ended up replacing the power supply and the machine now starts up again. Both RAM boards have a red LED lighting constantly while the computer runs... is this normal or does this indicate another problem ? could not find anything regarding this in the service manual...

the memory cage seems also a little bit hot when touching, even if the machine just ran for only 5 mins. Rear fan seems to be somewaht weak, but working. Any thoughts ?

Thanks !

 

[Dayo]

Both RAM boards have a red LED lighting constantly while the computer runs... is this normal or does this indicate another problem?

It does indicate a problem.

1.
Try reseating the risers

2.
Confirm that the RAM shown as present by the system matches what you expect.

3.
Swap out and recombine RAM sticks to isolate faulty sticks