A4 B6 3.0 Cabriolet 2003 - Battery Draining - Traced to Radio Circuit

Forestier

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Hi,
I have been having problems with the car’s battery going flat every few days.
I used the multimeter to measure battery amps and was seeing the reading rise from 20 to 30 milliamps up to 110 milliamps. Sometimes it would rise to 300 milliamps.
Oddly it would return to 20/30 milliamps after 10 - 20 seconds.
It stayed steady for about 30 seconds & would rise again.
Watching the meter, I started pulling fuses every time the meter peaked.
Pulled fuse 39 and meter dropped to 10 milliamps and stayed there.
Repeated a couple of times and confirmed that this was the problem.
Fuse 39 is the radio circuit.
I unplugged the Nav Plus head unit & the CD Changer.
Replaced fuse 39 expecting to see the meter stay at the 10 milliamp reading.
Instead, it showed the same drain as it did when head unit & cd were connected.
So
Has anyone gone down this route before?
Any help much appreciated!
Thanks
PS
1. I left fuse 39 out & measured battery voltage each day to see if it dropped significantly with the radio circuit disconnected.
Over a 4 day period the battery voltage dropped by an average of .05 volts in 24 hours.

2. Put the radio circuit fuse 39 back in.
Battery voltage dropped by .50 of a volt in 24 hours.
 
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I think I may struggle to fix this, does anyone know of good auto electronics specialist that could trace the fault. I live in the South but would travel to see the right guy.
Thanks
 
Whereabouts in southeast?

Which nav unit fitted, post a pic up.

Does the car have BT phone?
 
Whereabouts in southeast?

Which nav unit fitted, post a pic up.

Does the car have BT phone?
Head unit is the double din original Audi Nav Plus, the one with the tiltable screen.
I bought the car new in 2003 & it was a ****** expensive option.
The only thing is that the cyclical amp drain still shows when the radio & separate cd multi-changer are removed.
Location is Southampton but we are with the car in France for a few more months.
 
Does the car have bluetooth fitted?