PowerBook 520 Won't Boot

[l008com]

I fix Macs for a living.... but generally modern Macs. I had a customer ask me if I could get some old files off her super old powerbook and I said sure I'll give it a try. So she unboxes a PowerBook 520 that has likely not been powered on in 20 years or more. I plugged it in and couldn't get anything to happen. We left it and moved on to other things. I tried it again about an hour later and that time it DID power up! I copied some data and left. Now, a few months later, I need access to this computer again (and I have it in my possession). But I can't get it to power up. I've had it plugged in this time for something like 12 hours now. It just won't power on at all. No lights, no sound, no fans, literally nothing. Like it's not even plugged in. There is no battery installed, and of course I don't have a battery or a different AC adapter I could try. 

All that said, any thoughts?

 

[bibilit]

Probably a power supply issue, try to check outputs, if not possible, try to heat the psu with an hair dryer, if is related to capacitors it will work for a while. 

 

[l008com]

I have a multimeter, what voltages am I supposed to get from the power?

 

[Carboy7]

16 volts.

If you're having power fluctuations, take off the cord on the supply and smell. If it smells like fish, crack that sucker open and recap it.

 

[l008com]

There's 4 pins, is every pin putting out 16v steady?

 

[bibilit]

http://forums.macrumors.com/threads/powerbook-520-odd-behaviour.1855934/

 

[TheWhiteFalcon]

Unplug the three prong cable from the adapter (but leave the other end connected to the wall), let it sit for a bit, then plug it in again.

 

[techknight]

the backbird power supplies are getting bad for caps, I had 2. one I recapped back in 2000ish. Yes it was bad back then... 

the other I recapped recently and it leaking so bad, it was corroding the PCB like the 1xx adapters are doing.