random interference - unknown source

Pabs · 05-28-2005, 07:09 PM

peeps

My carpc has, since last week, started getting interference from an unknown source. Maybe someone can identify where it is coming from by the type of noise. Here is a description of it:

When carpc has booted up from hibernation it starts. It sounds like a tapping/clicking noise that occurs about 2 or 3 times a second for about 5 seconds, then stops. It then comes back about 20 seconds later. It COULD be some form of switch/relay or something, i dunno.

Now, it happens at a FIXED relatively quiet volume, and changing the volume of the music drowns the noise out. Also, muting the sound from the PC doesnt help, as the noise still exists.

As far as I can tell, it must be coming from the amp. Sound possible? It comes from all speakers in the car, not just one channel.

I have a JBL GTO 755.6 6 channel amplifier. The only thing that has happened recently is that i had 2 subwoofers, but 1 stopped working due to bad flow joints on the sub, which is now working but not in the car. I have bridged the two channels together for the 1 existing sub in the car. Nothing else has been altered.

Any help guys? I have searched but nothing close came up. Perhaps you knowledgeable people could point me into the right direction, perhaps giving some ideas as to possible faults?

Many thanks in advance guys!

ACHIEVER · 05-28-2005, 07:11 PM

Sounds like a ground loop.

Try unplugging the RCA's goinkng into your amp and see if it is still there. That will give you a starting point on where it is.

Pabs · 05-29-2005, 04:15 AM

a ground loop makes that noise? Ok - will have a look at some point - although nothing has been changed to do with that, and it did work fine for about 4months.

Pabs · 06-03-2005, 07:13 AM

well - problems sorted now - seems that it was something to do with my cold cathode tubes in the amp/pc. Have removed them all as 1 was broken anyway, and problem has disappeared.
Cheers