The electrolytic capacitors in laptop power bricks and most switchmode power supplies for that matter take a real beating. High ripple currents, high temperatures, long hours of operation, it's amazing they last as well as they do.
If you can crack the thing open, you'll find several capacitors in the output section that will be bad. If you have access to an ESR meter, they will likely test very high resistance, sometimes even open. Often they will be bulging or leaking electrolyte, but I've seen plenty of bad ones that looked just fine. Once in a while even the large main filter capacitor (careful, that one can zap you!) will also be bad. If the supply works at all, then 95% of the time replacing the capacitors will have it running like new.
All that said, I have a PB520 which is missing the power brick entirely. If anyone has a dead but complete one they don't want, I would gladly pay postage.
If you can crack the thing open, you'll find several capacitors in the output section that will be bad. If you have access to an ESR meter, they will likely test very high resistance, sometimes even open. Often they will be bulging or leaking electrolyte, but I've seen plenty of bad ones that looked just fine. Once in a while even the large main filter capacitor (careful, that one can zap you!) will also be bad. If the supply works at all, then 95% of the time replacing the capacitors will have it running like new.
All that said, I have a PB520 which is missing the power brick entirely. If anyone has a dead but complete one they don't want, I would gladly pay postage.