Mac G5 one flash

Welcome!

Please help us help you. Is this about a G5 iMac:

or a G5 tower?

There can be hardware differences at play, especially with power issues.

However, some issues can be common to both. This statement you wrote is raising a HUGE red flag for me:

It was at my garden house.

I may be misinterpreting "garden house," but to me that says "garden shed" or "greenhouse." I hope I am wrong!

If the "garden house" has high humidity, condensation may have formed on the logic board and connectors, corroding and compromising components. This is compounded if the garden house lacks year-round temperature control and sees big swings in temperature.

By "flash," do you mean a visual lighting up or sparking? If so, something important has shorted. Given the paucity of repair parts for ancient Macs, that could be a fatal blow.

If a G5 Tower, you can remove the side panel and look for signs of arcing—soot or puddles of melted metal. This Apple manual shows on page 46 how to open the panel on a G5 Tower.

https://cdsassets.apple.com/live/6GJYWVAV/user/ma115_power_mac_g5_late_2005.pdf

I cannot recommend opening a G5 iMac to the average user.

Any damage like this is almost impossible to diagnose remotely via these or any other forums forums. Apple does not service old models; for professional evaluation you'll need to find an independent provider who is has been in the business enough to remember G5 Macs.

I am an optimist when it comes to rehabbing old Macs on a hobby basis, but I have a bad feeling about what you have described.

Thank you—that is a great help.

Your description sounds familiar, like the power supply failing as soon as it was activated. That is usually the most common source of trouble in G-series towers going back to the G3 mini-towers. I suppose the good thing is that a PS may be easier to find than some other components.

Roughly where are you located? If in the US, there are some Mac parts vendors who may still have really old bits and they may have the power supply. Outside the US, I have fewer ideas where to look.

However, there may be more than one PS wattage used as the G5 evolved. If you search for a power supply, you first need to pin down the exact sub-model of your G5. As it won't start, you have to get it from the serial number. First, try Apple:

Check Your Service and Support Coverage - Apple Support

Two issue there: (1) It may not go back far enough, and (2) Apple recently dumbed down that function at the Altar of Minimalism, and it does not alway show the sub-model as it once did.

If either is the case, I have used this free service for years without issue: Ultimate Mac Lookup

Lacking that, post a picture of the label BUT REDACT THE SERIAL NUMBER before posting. From the processor description and other non-personal info on the tag, we may be able to narrow it down for you.

That said, I believe I am seeing schmutz on some of the metal parts inside that could be condensation staining. That bodes ill for other components.

So...if you only need to recover data files from this computer, the drives are easily removed. You can use a dock or bare drive adapter to connect the pulled drives to any computer with USB ports. This one has the required power cable needed when extracting data from the 3.5-inch drive types in a G5:

NewerTech Universal Drive Adapter for 2.5-inch, 3.5-inch, 5.25-inch, IDE, ATA, ATAPI, SATA Drives

The above firm is US but has partners in other countries that may have the adapter. In the long run, and only needing to recover data, that could be the most effective solution, considering a new PS could cost 4-6 times that and still not fix the computer if moisture has compromised other components.

Allan