gnarf wrote:It fried the power brick and fried something inside which prevented my battery from charging when I got a new power brick. I thought it maybe fried the battery too so I bought a second battery only to discover that wasn't the problem. so I sent it in to get repaired, luckily it was on the last month of warranty coverage. laptops are like a UPS when the power goes out it will still run, but it is not like a UPS when it suffers a power surge, well maybe very small surges but a laptop will not protect you as any surge protector.
It's a bit like that, but not quite. A laptop provides surge protection because it's a buffer -- the person who said this is correct. Generally a laptop draws power from the brick, which puts that potential over the battery. The laptop components draw power from there. So if the brick fries, the components are somewhat protected - assuming your battery doesn't burst or something.
That being said, there is absolutely no reason to let your laptop sit there without surge protection, even if the battery would probably be a sufficient buffer to protect most of the components in the laptop. There is no reason to rely on this - and it may not be sufficient, depending on circumstances. I like these little buggers:
But a surge can cause damage to the laptop hardware between the brick and the battery -- the two are not directly connected. There is usually a second PCB (maybe not on a netbook, but I think probably still a separate PCB even with space-saving in mind). This PCB handles the DC from the brick, and gives it to the battery. It's handy to know this, because if your little power socket gets loose -- after six years, I replaced the one on my old Acer, which was was... okay I won't make the usual Oprah joke, but you get the idea. You can get the small PCB for this on ebay or such a place, replace it, and the laptop ought to work. This is, presumably, how your laptop was repaired.
freetek wrote:It won't; you need an isolation transformer with galvanically separate primary and secondary.
The hum you are getting is more likely caused by poor shielding or a floating case on guitar or one of your effects.
It may be the guitar, but it could easily be a potential between the PC and guitar/pedals (even if the pedals and PC are on the same outlet/power strip).
Computer sound cards often have bad grounding, and there could easily be a (difficult to fix) problem with the grounding somewhere in there. I would say this is probably the problem - a ground loop, but the issue is probably in the laptop sound card or adjacent components.
I would suggest plugging this into an amp (properly grounded, of course) and checking for hum - that way you can be more sure it's the laptop. Of course, if you're playing guitar through your PC, this may be due to a lack of amp.
Unfortunately, I don't think a new surge protector will fix this problem.