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Quadra 700 doesn’t power on anymore


Hello everyone,

I’m going to copy-paste what already have asked in some Discord about Macintosh stuff.
My Quadra 700 does not power on anymore and I’m very sad about it. I did quite nothing, it worked until now.

I did not recap it. But it really scares me since I do not have time, space, will to make it. And honestly I would not even know which type of capacitors I need...

Since I opened the PSU (which even worse, today dropped on the ground from my chair! :'(  really I’d cry!) I though that might be the problem. I also thought it could be the fact that I attached the monitor to it. Unfortunately I did not test the Macintosh as it was before so (as I said, I first tried to power on the monitor alone by connecting the monitor to the PSU and this to the power outlet)

Guys... I’m really sad...
I have a Quadra 700. It worked but needed a battery replacement.
So I removed the old one and I left it in a box until yesterday, when I put the new battery.
In the meanwhile the new battery arrived, I opened the PSU to remove all the dust.
Also, I tried to power the monitor using a three-phase extension cord connected to the Quadra PSU. I wanted to fo it from months.

So, what I have done has been:
• removed the old battery
• waited 3 weeks
• cleaning the PSU
• testing the PSU alone with the power cord plus the extension cord connected to the monitor (nothing happened though, I expected the monitor to power on)
• putting the battery in the Macintosh
• putting the PSU in the Macintosh
• click the power button on the Quadra, plus the power key on the keyboard but nothing happened! Nothing at all.


Well-known member

The good news is that Q700 Logicboard normally doesn't need recapping since there isn't any smd electrolytic capacitor on it! For the PSU it's clear most of them are out of order now :( . Sadly recapping the PSU is rarely sufficient to bring it back to live...

The solution is to replace its internals with an ATX PSU circuit (or make your own and put it inside the original PSU case). Many people have succeeded in doing this!