Online, you can find a lot of discussions related to what power brick to use with Macintosh Portable (the original is M5136 7.5V 1.5A), if it has to be exactly 1.5A or can be more and if it’s worth recapping the power supplies.
I decided to at least somehow help in those discussions with verifying two hypotheses on the bench:
So I took 3 PSUs on my bench:
By the way, here’s the archived Apple Technical Article about the PSU part numbers:
http://web.archive.org/web/20100423034550/http://support.apple.com/kb/TA32393
Regarding the claims that using a high wattage adapter on Portable might be dangerous, Apple in this TA seems to be suggesting something similar for PB100 and PB150:
Yes, definitely!
The old capacitors in those PSUs tend to lose rated capacitance and leak. The current curves in my case were slightly affected by the capacitors, I’m pretty sure that dynamic characteristics (eg. impulse response) would make it even more apparent.
Leakage is another problem - the capacitor goo really eats out the soldermask and copper traces, making the PSUs simply non functional. Out of the three, ADP-17AB had pretty apparent traces of capacitor leakage:
The soldermask was eaten away already and the copper was affected.