Bad power, blown fuse?

[hydro]

Hey folks --

Last night at rehearsal my bass player blew a fuse in his JCM 800 Superbass MKII head. The amp has a history of doing this, although we have had a tech check it out a couple of different times and he found nothing wrong.

Moments after that, our PA - which is plugged into the same circuit as his head -- made a nasty pharting sound and blew both woofers in our PA speakers.

My question is, can unstable power or poor power line conditioning cause a blown fuse? I kept thinking it was the JCM head that just had a bad solder or something in it, but after the PA blew out I am starting to wonder if the problem is actually the electrical circuit we are all plugging into.

Not only am I worried about the power, but I am trying to keep my bass player from resorting to using his Sun Coliseum head, because it is SO FREAKING LOUD even when it's dialed in around 2 or so.

I am not an electrician (obviously) and I know nothing about electrical stuff, other than how to turn stuff on or off -- so any advice or suggestions would be appreciated --

 

[Gone_Shootin]

Re: Bad power, blown fuse?

The other guitarist in my old band had problems with his Peavey XXX after they played a show before I joined the band. I was in the audience that night and there was some sort of weird power fluxuation. His amp didn't sound right afterwards.

So when I joined the band, I went to my local Walmart and bought a surge protector. Granted, it's not as good as a power conditioner, but it will smoothen out any spikes.

 

[zzmoore]

Re: Bad power, blown fuse?

The other guitarist in my old band had problems with his Peavey XXX after they played a short before I joined the band. I was in the audience that night and there was some sort of weird power fluxuation. His amp didn't sound right afterwards.

So when I joined the band, I went to my local Walmart and bought a surge protector. Granted, it's not as good as a power conditioner, but it will smoothen out any spikes.

It could always be 100 different things.....but from the info provided, I would take the above approach.
Buy something that will take the hit from a bad power Spike/Main/Supply/Crappy wiring In House/etc etc etc.
best

 

[crusty philtrum]

Re: Bad power, blown fuse?

Buy a power-point tester and check the wall outlets that you were using before going any further.

If the rehearsal space is used by others, ask them if they have had any problems.

 

[hydro]

Re: Bad power, blown fuse?

We do have power bars on there but I'm not sure if they have surge suppression in them.

No history of problems that I know of, other than what I mentioned.

I guess what I am wondering is if an amp's fuse is supposed to protect it from external surges, or whether it is to protect the amp from totally smoking if some small internal component inside the ampfails. Or is it for both??

I don't know why electrical stuff is so baffling to me. When people start talking watts and volts and amps and fuses and capacitors and transformers, it might as well be Mandarin.

 

[zzmoore]

Re: Bad power, blown fuse?

The fuse is there to prevent the building from burning down.
Lots of stuff internal to the amp can fail by the time the fuse snaps.

 

[Demanic]

Re: Bad power, blown fuse?

I knew there was a reason that I run a power conditioner. And if one piece of equipment fails in a circuit that contains others, it can produce a surge while doing so that can later affect other items.

 

[zzmoore]

Re: Bad power, blown fuse?

Probably (though I Am Not a tech or engineer...so i am just guessing) the best way to protect your amp, is by employing multi fuse protection.....the style we see in most "modern day" amps.
Usually there is a Mains Fuse...followed by a Filament Fuse and also an HT Fuse.
But there will always be a compromise of protecting the device, and not having fuses snapping all the time. There has to be enough wiggle room for the device to function in the "real" world.

 

[Johtosotku]

Re: Bad power, blown fuse?

It is possible that bad electricity comes out of the socket. It may also not be the cause of the problems, even if the phenomenon exists in the location.

But there will always be a compromise of protecting the device, and not having fuses snapping all the time. There has to be enough wiggle room for the device to function in the "real" world.

That would be accomplished by time. Fuses accept current over their limit for certain periods of time. The higher the current, the shorter the time. Having the current just a tiny bit over the treshold can take ages for the fuse to blow. If the overload isn't consistent over time, it can still weaken the fuse for future overloads.