Mouse, CPU noise problem

[llebron]

I'm a musician and I've been using my "old" Pentium II Notebook computer to play MIDI files via my USB (1.1) port into a Roland UA-100 Audio and MIDI processing unit. The UA-1oo is connected to an Edirol SC-88 sound module, and the output is connected to my PA system. I'm been using Cakewalk Guitar Studio and this set-up has worked very well for me for many years.

I decided to update my notebook for a new Pentium 4 with more RAM, Hard disk capacity etc. This has turned into a major problem.

I've bought, tried, and returned 3 different notebook computers because they all cause the same situation: Excessive noise through my speakers when the system is idle, and even more noise when I move the mouse. Needless to say this is unacceptable in a live performance situation.

I've narrowed down the problem to the AC power supply required for the more powerful and demanding Pentium 4 notebooks. If I run the system on battery power the noise goes away - BUT I cannot rely on the battery for an entire evening, when it starts dying the MIDI timing is affected.

I usually have only one outlet to plug all my equipment into it most clubs so I'm using an APC Backups UPS and a power strip.

My Question: Is there some way to isolate this noise.

Please help
Thanks
Lou

 

[GregANDTCH]

Does the noise change if you bypass the UPS & power strip & plug it directly into the wall?
Maybe one of them is introducing noise.
Is there a good ground between all these devices?
Maybe it's a bad ground wire.
Just guessing🙁

 

[Souka]

you said you tried "three different notebook computers"

Did you try the same model/make? or were they all different?


A suggestion would be trying an IBM X22 or T21/22/23 series....they're a P3 class notebook, durable and reliable.
IBM tends to put more R&D into their equipment....such AC-noise is less likely I would think.

My $.02

 

[nickaskew]

Hi

You say you are certain it is the AC power connection that introduces the interference, this leaves several options for you to try - put in order of expense:

1) Shield the audio cable you connect between your notebook and roland - just wrap standard foil around the audio cable (the same foil you would cook a joint of meat in.. )
2) Try using an AC line filter on your notebook's power lead - probably not this option if you are using a UPS and experiencing the noise - UPS's are supposed to filter the line anyway - do you get interference when your UPS IS NOT connected to the mains?
3) LAST DITCH ATTEMPT (consult with an electrician if I were you): If your notebook has an Internal AC/DC adapter (you have an internal one if your power lead is a single lead - no black box half way up it), then carefully dismantle your notebook and isolate the PSU, wrap the PSU in foil (or RFI dampening material) - MAKE SURE the foil isn't touching any metallic parts of the PSU...... MAKE SURE THE FOIL ISN'T TOUCHING ANY METALLIC PARTS OF THE PSU!!!! - please note: THE FOIL CANNOT TOUCH ANY METALLIC PARTS OF THE PSU!! hope that was clear!

I wouldn't say it is an earthing problem if you have tried several different notebook models... I am fairly confident this noise is RFI based.

Best Regards,

Nick