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Our Mac Pro A1186 which was turned off for a while during Covid, now does not turn on anymore.

When pressing the power button, it makes a clicking sound, then 3 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 lights up as is yellow, indicating that trickle voltage is present

My questions:

(1) would this mean that the power supply has failed ? Reading the service manual, this seems to be indicating just that.

(2) what is the part # for the power supply to get a replacement part ?

(3) is it possible to use 3rd party (non-Apple) power supplies in the Mac ? If so, what would be the required specs ?

(4) any suggestions on where to purchase a replacement part ?

Thanks.

update: 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...

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2 Answers 2

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Having worked on Mac Pros of this vintage (the A1186 had 3 different models between Aug 06 & Mar 09) there could be any number of things wrong from a bad HD (the clicking) to a toasted power supply.

One nasty side effect of a zapped power supply is there is a possibly of some collateral damage to the main & peripheral boards, PCI cards, HD power supplies, etc, when it either degraded over time, experienced a sudden failure, or was electrically damaged by a bad AC power transient from the premises wiring.

You need to replace the PRAM battery as well. A simple alkaline CR2032 button battery should do the trick.

Removing and reseating every PCI board, ribbon cable, and RAM module is also recommended, but only if you know what you're doing! Replacement parts are next to impossible to find, however.

I assume you've followed the troubleshooting steps starting on page 152 of the MacPro A1186 late 2008 service manual (which I've included here for others who are seeking this info.)

Another option is something like this site for a source of spare parts, or just to start from scratch.

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  • I'd change the battery & re-test before anything else. They can cause all kinds of random issues if they're dead.
    – Tetsujin
    Commented Jun 26, 2022 at 7:27
  • thanks for the tip re the battery. just replaced that, same result. But, for whatever reason, one time while connecting the power cord (and the new battery in place). the white front LED now started blinking permanently... but no other time after that... HDD and everything else has been removed, PSU still makes the same two clicks... I guess I'll order a replacement power supply and see if that fixes it...
    – peterf
    Commented Jun 27, 2022 at 5:22
  • updated the OP, finally replaced the power supply. systems starts up again but both RAM boards now have a red LED lighting constantly... is this normal ? Thx
    – peterf
    Commented Jul 22, 2022 at 6:37
  • The red LED is most likely normal. If the System Report shows all installed RAM modules, then things seem to be working correctly. Congratulations! It is a wondrous thing when the POST startup chime fills the air, the screen flickers to life, and all is well.
    – IconDaemon
    Commented Jul 23, 2022 at 16:49
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Дамы и господа если вы это читаете то вы столкнулись со схожей проблемой что и у меня. На мак про а1186 мигает индикатор постоянно и пк не издаёт звука но работает? Ок это уже что то теперь внимательно посмотрите на материнскую плату на ней в раене оперативной памяти есть индикаторы cpu b,cpu a. Так вот данные индикатор на cpu b во второй графе еле-еле светил по мануалу проц тротлит и не хочет запускаться. После замены комп снова запустился и все прекрасно работает так что пользуйтесь) я сам много сайтов перелестал и если кто то ищет решение знайте вы не одиноки. Я попробую записать видео как именно решил эту проблему что бы каждый мог исправить. P.S при разборе будьте осторожны можно сломать крепления кулеров если расстались. #Mac Pro не включается мигает Power постоянно

English translation:

Ladies and gentlemen, if you are reading this, you are faced with a similar problem as I did. The indicator flashes constantly on the Mac about a1186 and the PC does not make a sound but works? Ok, it's already something, now take a close look at the motherboard on it in the RAM area there are indicators cpu b,cpu a. So the data indicator on the cpu b in the second column was barely shining on the manual percent throtlit and does not want to start. After the replacement, the computer started again and everything works perfectly so use it) I myself went through a lot of sites and if someone is looking for a solution, know that you are not alone. I'll try to record a video of how exactly I solved this problem so that everyone can fix it. P.S. when disassembling, be careful, you can break the cooler mounts if they parted. #Mac Pro doesn't turn on, Power flashes all the time

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  • Welcome to Ask Different. Thanks for a good first answer, but in future please note the site is English-speaking. As a courtesy, I've edited in a (machine) translation for you. Please feel free to edit it if required.
    – Andy Griffiths
    Commented Jan 10 at 22:58
  • would love to see the video to see exactly what you've done! Thanks!
    – pete19
    Commented Jan 12 at 21:31
  • Gentlemen, I perfectly understand that different people are sitting here, but we have the same problem with computers, so I shared it) And so this problem is constant, the flashing power indicator is caused by a burnt-out processor, and just in case I advise you to replace both with an x5355 processor P.s It doesn't matter who you are Russian American or German and so on, the main thing is that you have to help people)
    – Люцифер Денница
    Commented Jan 13 at 22:13

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