Balanced Power Question

[ajcamlet]

I have a Furman 20 amp balanced power supply running all the audio stuff in my control room.

I upgraded to a MAc G5 dual 2.0 from a G4 Dual 867. Every time I Power up the G5 the GFI circut on the front of the furman trips. I dont get it- i didnt have this problem with the G4 at all. Should i *not* have this computer on balanced power?

thanks for any insight!

alan

[Leo Badinella]

Originally Posted by ajcamlet

I have a Furman 20 amp balanced power supply running all the audio stuff in my control room.

I upgraded to a MAc G5 dual 2.0 from a G4 Dual 867. Every time I Power up the G5 the GFI circut on the front of the furman trips. I dont get it- i didnt have this problem with the G4 at all. Should i *not* have this computer on balanced power?

thanks for any insight!

alan

weird. I have 2 furmans for most of the audio stuff here and I have a G4 and a Wincrap too but they are not hooked up to the Power Conditioners. Instead I have them plugged to a UPS each. And I've never had the problem you have.

I had one of the furmans short one time because the overall net voltage of the studio had dropped to 104-5v (if I remember correctly), and the UPS the PC is on would sometimes short when I had a CRT monitor hooked up to it too.

Your furman shouldn't be shutting of with a G5 load, 20 amps is plenty. I would suggest you get a UPS for the G5 and plug it in the same power outlet as the Furman.

[dementedchord]

sounds pretty weird to me is the gfi on the unit or the wall? the only thing i can think of is maybe.... normal ac has basicall 2 grounds... 1-hot 120 v 2- cold ground #1 and the ground green wire ground #2 .... now the wal a balanced supply works is it is wired as a 1-1 ratio but has a center tap which it forces to ground.... the ac then apears as 60v on each of the ends of the tranny.... makes sense??? theend result is the same thing that happens with ballanced lines for audio.... the same noise occurs on both lines in this case out of phase alredy(no need to flip one side) so the noise cancells and your noise floor drops appreciably.... what i susoect is that something doesnt like the ground being forced tries to stay as it was and your getting massive in rush current..... was the g5 the only change????

[vince @ speck]

Originally Posted by ajcamlet

I have a Furman 20 amp balanced power supply running all the audio stuff in my control room.

I upgraded to a MAc G5 dual 2.0 from a G4 Dual 867. Every time I Power up the G5 the GFI circut on the front of the furman trips. I dont get it- i didnt have this problem with the G4 at all. Should i *not* have this computer on balanced power?

thanks for any insight!

alan

Perhaps the answer is that the GFI is tripping because of a "ground fault". Have you considered that your G5 might have a flakey ground and the Furman is doing what it is suppose to do!

[JonCraig]

GFI/GFCI are notoriously over-sensitive. on startup, the g5 is pulling max current... it's simultaneously spinning up the fans (takes way more power to spin them up than to keep them spinning), spinning up the drives, applying bus power to firewire & usb, monitor, and (probably the biggest) charging each and every capacitor in the machine. the gfi sees that sudden of a draw as a fault, and trips. is there a non-gfi outlet on the furman?

--jon

[ajcamlet]

thanks for all your replies guys...

yea, the G5 was the only change. Now- my understanding is that this run of G5's is not the most solid build so it wouldn't surprise me at all if the PS was flakey.

I'm wondering if the Apple cinema display could be a culprit. on the G4, the was a dedicated ADC port for the screen. On the G5 they discontinued this port (bastards) and force you to buy an external DVI->ADC port that is self powered. I tried to trouble shoot this by plugging that converter into another breaker, completely separate from the furman- yet the furman still tripped.

[KingDaddyO]

Originally Posted by JonCraig

GFI/GFCI are notoriously over-sensitive. on startup, the g5 is pulling max current... it's simultaneously spinning up the fans (takes way more power to spin them up than to keep them spinning), spinning up the drives, applying bus power to firewire & usb, monitor, and (probably the biggest) charging each and every capacitor in the machine. the gfi sees that sudden of a draw as a fault, and trips. is there a non-gfi outlet on the furman?

--jon

An electrician friend of mine (also a bitchin' guitar player!), says that the only way to know if the GFI is tripping at the proper level, is to test it while measuring the trip levels. Says he sees a lot of variation towards the safety side (i.e., tripping with less current than more). And that is a good thing, since GFI circuits are only required by national elec. code, to be used in areas where water is a safety issue (bathroom, pool, etc). Not sure if a dry recording studio is the best application for such protection, but I can see where the filtered power would be nice.

Like Jon said, it's likely that the G5 is pulling more current than the G4 on startup, maybe even during normal operation.

And as Vince said, there's no reason you couldn't also have a ground fault with the new gear. See if you can borrow an ampmeter to clamp around the power cord from the G5. If you can measure the actual startup current and it is within spec. for the Furman, then you should be able to get the manuf. to repair it or replace what might be an overly sensitive unit.