Radio interference when using heated rear screen.

[vrbob]

As title suggests i am getting interference on my radio when i out the heated rear screen on. The signal seems ok when in normal use but as soon as i press the button for the heated screen the radio goes all hissy and only returns to normal once i turn off the heated screen.

I did do a google search for this issue but didnt see any answerss to help solve the problem.

I have checked the back of the stereo and thats fine no issues there.

I took the trim off the inside of the tailgate and checked the connections i spotted that one of the wires was detached from the rear window so have re-soldered this back but still got the same issue.

There are 2 little FM things on either side of the screen marked left and right i done know what these are but do they boost the signal and could they be the cause of the problem?

 

[DaveA3]

i get this if i turn my lights on full. dont listen to radio so dont bother me really

 

[vrbob]

i am upgrading my Syphony2 HU to RNS-E soon so will see if the problem persists but any other solutions that i can investigate would be appreciated

 

[TDIQ]

Is it just radio, not CD? Does it affect FM, LW and MW?

 

[vrbob]

Is it just radio, not CD? Does it affect FM, LW and MW?

Checked this morning and its just FM that seems to be affected

 

[DaveA3]

mines on an alpine stereo. i have a sneaky feeling mines just loose i dunno. probably an unrelated issue

 

[vrbob]

mines on an alpine stereo. i have a sneaky feeling mines just loose i dunno. probably an unrelated issue

Yeah not heard of headlights causing this before so your probably right. The prob i have is known as when i googled it the prob was related to other models too EG the 8P, A6 and TT but couldnt really find a solution for it.

Someone mentioned checking the rear screen for breaks in the lines so have done this and found a slight break which i have now repaired but still the problem persists.

 

[Smokey_clark]

I get this too, let me know if you want me to check anything. I'll look for broken links in the screen wiring in a bit.

 

[TDIQ]

It could be a possibility that the amplifier in the aerial on the roof has stopped working properly.

 

[vrbob]

i took the Bose amp out and had a look at that and it seemed in perfect condition no corrosion (thought maybe water had got to it) so just put it back together.

Is there a seperate amp for the aeriel if so where is it located as the only bits i found were the 2 weird FM things attached to the tailgate either side of the glass under the trim but not sure what these are or what they do.

 

[TDIQ]

It's the amplifier within the aerial base but I think it's to do with the screen itself. It could be a simple short.

How did you fix the break in the rear screen element? Are you 100% sure that it's fixed?
It might be worth steaming up the rear and use the rear screen to check that there isnt any obvious areas that aren't clearing or check each line.
Are you sure that the wire that was detached from the screen originally should be attached?
Are the "FM" things you mentioned the inline amplifiers? They may need replacing...

I know these are pretty basic questions but it could help to narrow it down a bit

 

[jasona3turbo]

iv heard this is common on a3s

 

[vrbob]

It's the amplifier within the aerial base but I think it's to do with the screen itself. It could be a simple short.

How did you fix the break in the rear screen element? Are you 100% sure that it's fixed?
It might be worth steaming up the rear and use the rear screen to check that there isnt any obvious areas that aren't clearing or check each line.
Are you sure that the wire that was detached from the screen originally should be attached?
Are the "FM" things you mentioned the inline amplifiers? They may need replacing...

I know these are pretty basic questions but it could help to narrow it down a bit

The rear screen in my car has been replaced at some point as when cleaning it after i bought it i found some bits of glass inside the boot under the spare wheel etc So am pretty sure its not the original one but defo looks like an OEM part.

I have checked all the lines in the rear screen and the one i repaired wasnt working and after the repair now is so i am pretty sure i have fixed it. To fix it i used some of the stuff you can buy that is like a touchup paint but conducts electric current so a bit like liquid metal.

The wire i re-attached was on the right hand side and solders to the rear screen in 2 places (there is an identical wire on the other side of the screen) yeah i am pretty sure it should be attached as it did look like it was fitted there but had come away from the glass.

The 2 FM thingy`s could well be inline amplifiers as i said am not 100% sure but i bet they are expensive lol

Cheers for your advise

 

[vrbob]

With the mornings being colder the last couple of days i have had my heated rear screen on and noticed that 2 of the lines near the bottom on one side were not clearing.

Checked them last night and could see a faint gap so used dome more of the electrostat paint to repair them and this morning they were working and also my interference on the radio seemed to of fixed itself

Will see if the problem is still gone 2moro morning on my way to work bt hopefully that was the cause of my issue and if so not a difficult fix once you have found which lines have breaks in them.

 

[vrbob]

Just to confirm that fixing the broken lines in the rear screen solved the interference i was getting so if you are having issues this would be a good place to start.

 

[Moony_1989]

Where did you get this touch up paint from to fix the rear screen?

Do you have a link?

Radios driving me bonkers!!

 

[s3mad_dude]

I bought some from ebay once. Conductive paint. Halfords used to sell it back in the days but haven't seen it there for ages so got some on eBay.

 

[vrbob]

http://www.ebay.co.uk/itm/Electro-C...914?pt=LH_DefaultDomain_3&hash=item462d03ca9a

This is the stuff

 

[vrbob]

Best bet to find the broken parts is first to get the rear screen fogged up (use your breath) and see which lines don't work. Then get a torch and put it on the inside of the glass as you look in from outside. Move along the line and see if you can find an broken sections or as I found a section that looks a bit feint and touch up those areas. Once dry re test the working of the lines and once all clear the fog hopefully your radio will fix as mine did.

Rob

 

[HansfishS3]

Ah great post, funny enough this just started happening on my dads c class!

 

[Moony_1989]

Found part of the cause. Took my led number plate bulbs out and now the radio is working spot on, little fussy with the heated screen on but a lot more bearable!!

Must be getting some resistance somewhere along the circuit!

Gna try some different bulbs in the coming weeks