Powermac G4 Quicksilver won’t turn on

[mattemangia]

Good Mormont from Italy!
I hope someone can help me with my little problem. Recently I discovered a powermac G4 Quicksilver in a flea market. The psu was dead, even with the Green pin trick it won’t work. Now the thing is.. I’ve bought an atx psu, and I changed the connector following a simple tutorial on the net.. the powermac is not turning on: the power button isn’t working, neither a bridge between the power pin on the mobo. The pmu battery is new. The only way I can turn the mobo on is by making a bridge between COM and POWER pin on the molex connector, but doing so won’t start the processor (the screen stays black and no chime). I’ve pulled out the processor board, but there aren’t signs of burn.

Someone with more experience than me could help, please?  I don’t want to throw it in the garbage.. 
Thank you in advance

[reeskm]

Hope you haven't thrown it away yet!

Just out on a limb here, but if you tried using a PC ATX power supply, it may not turn on because it might use a different way of triggering power on through the ATX power connector to the mainboard. In other words, the motherboard 24pin ATX connector might not have the same pin-out as the Quicksilver's original PSU.

"The Power Mac G4 MDD Used a uniquely shaped 344W or 400W AcBel or Samsung Power Supply. It had a 24-Pin Connector (not 24-Pin ATX!)" See https://www.ifixit.com/Guide/Power+Mac+G4+MDD+Power+Supply+Replacement/1622
(I know you do not have a G4 MDD but the principle is the same)

I would recommend ordering a replacement PSU off eBay or a mac parts reseller that supplies older parts. Maybe someone here on the forums has a spare PSU you could buy?

Don't throw it out yet! It seems to have a 1 GHZ dual processor! That sounds like a great second hand machine.

[reeskm]

Just found this!

Crazy hacking, but it works! This is what you need to do, if you don't want to order a replacement AC Bell power supply.

http://www.applefritter.com/?q=node/23857