Bad Reception of Key Remote and Radio FIX!!! Yes Really by matthewssawyer

11 minute read

Bad Reception of Key Remote and Radio FIX!!! Yes Really 

Compliments of matthewssawyer @ audiforums.com

4-19-2013

So, like many others out there, when I purchased my A4 B6 I noticed the radio didn't find channels on its own and the lock/unlock range of the remote was very poor. After reading many threads about this issue, I had given up hope for a fix. Well, I recently lost my job and in the interim I am trying to keep busy while hunting. Cheap/free car mods and fixes go! I started to scoured the internet again for more information on this issue. What I gathered is that if the rubber covering the electrical components has cracked, you likely have this issue. I don't see any reason why this would have damaged the board but there is a correlation. I am going to walk you through what I did to remedy mine. Unfortunately, I did not do this very scientifically so I am not positive which aspect fixed it. Try the easiest ones first then move to the more complicated I guess. I also didn't expect this to work and so did not take any photographs. My apologies. Here is a link to another member's thread with some photos and information: General Info AM/FM Antenna Booster. Much thanks to mdzaudi because his thread got me thinking I may be able to fix mine. Last clerical thing: I am not responsible for any damage you do to your vehicle during this fix. This is not a slop-through-easy-to-do-with-no-experience fix. You can very easily damage your board more than it may already be. Proceed at your own risk. On to the fix!

The above link shows with photos how to do this part so I will be brief. Remove the plastic cover covered in cloth above the rear seats and covering the top of the rear window. There are 5 metal clips and 4 or 5 plastic clips so just confidently pull. You will hear metal on metal that sounds like damage but this is expected. Once the cover is removed you will find the board mounted on the driver's side rear window. There is one black ground and 3 plugs: grey, tan, and white. Disconnect all 4. There are 6 plastic clips holding the board onto a plastic retainer. Carefully pry the 3 clips back along one side and the board should come out. I say carefully because at this stage in your A4's life it is safe to assume that all plastic bits are brittle. With the board removed it is time to do some inspecting.

There are either 4, 6, or 7 spring type connections on the non-rubber side of the board. Inspect these to see if they look "dirty." Mine were and I used a fine sandpaper to bring their shine back (better contact). Do the same thing with the contact points on the window. Mine were so dull and oxidized that I am suspicious that this was the only thing that needed to be done. Unfortunately, I did the "more complicated" process first based on what I had researched already. With your electrical contacts nice and shiny, reattach the board and see if the problem has been resolved. If yes, go have a beer and enjoy your newly found radio stations and remote lock/unlock distance. If, however, this has not remedied it then move on to what I stupidly did first.

This is the more complicated and risky portion of this fix. With the board removed, it is time to remove the rubber covering the electrical components. I can not stress this enough: do this sober. Do this well rested and with time to be slow and meticulous. There is a chance that some of the very tiny electrical components on your circuit board have come loose. While we remove the rubber these weakened components will want to come off with the rubber. Take your time. Be patient. And work in a well lit area so you can see below the rubber as you are pulling it up. You are playing chess against the rubber and all you need to do is think ahead to apply the least stress to components as possible. Again. SOBER. SLOW. PATIENT. WELL LIT. Moving on...

The rubber will not want to come off of the board at room temperature. Time to requisition our trusty (please be clean) toaster oven. If you don't have a toaster oven you can use your full size oven. Again, be careful. Take your time. We will be setting the toaster oven to 250*F at this point and allowing the board and rubber to acclimate to this temperature (about 10 minutes once preheated). I set my board on some tooth picks on a sheet of aluminum and placed it in the toaster oven. After ~10 minutes, remove it and begin to carefully peel the rubber up. There are many small components on the board so, again, take your time! I used my finger nails so I could feel what was under the rubber. You may choose to use a tool just be careful. You are going to hate yourself if you accidentally remove a component with your tool! When the rubber begins to be difficult to remove (too cool) put your board back in the oven for 5-10 minutes. Repeat this until all the rubber has been (patiently and carefully) removed from the board. Some of the board is just exposed PCB substrate and the rubber sticks to this very well even when warm. Use of a flat head in this area is safe so long as you are sure there are no components. Try to get as much rubber as you can off without damaging anything. There is a mosfet near the 3 plugs on the end; rubber will be stuck under the three pins of the mosfet. This is ok. This happens on the multi-pin chips as well. No worries. Get as much rubber as you can without the possibility of damaging connections or components. There is rubber on the back side of the board covering the 3 plugs' joints. Remove this as well. Now that your board is naked and shamed it is time to move on to the next step.

So long as you took your time, were patient, and had some luck, you should now have an exposed circuit board that you can inspect. Check for any visibly broken connections or components. Check the rubber you removed to be sure that you didn't pull off any really small diodes, resistors, what have you. If you have removed a component, save it and attempt to solder it back on. I did not have any difficulty getting the rubber off without damaging any components, and I wish the same for you. Now comes the risky but necessary part of this fix (assuming the cleaned connections didn't fix yours): PCB re-flow. If you are unfamiliar with this then it is Google and YouTube time. The idea is that you slowly and carefully reheat the board to a specific temperature to allow the solder to re-flow. Over time cracks can develop in the original solder joints and re-flow allows these cracks to be fixed. I have done this to graphics cards that were "trash" for our computational chem lab in college and it worked like a charm. The trick is not melting and burning your components. This is why we want to remove as much rubber as possible. The re-flow procedure I developed and used melted any remaining rubber but did not burn it. OK. Re-flow time.

***If you are using an oven for this next step, I would adjust the ramp up times I am about to give to be slightly longer as it will take more time to reach the desired temperature. Maybe 15 minutes to get to and hold 360 and 4 or 5 minutes to get to 420 and hold. On that same token, you will need to be vigilant during the ramp down. A full size oven retains heat MUCH better than a toaster oven. 420 will melt your plastic plugs if held too long. Proceed with great caution!***

Set your board in the 250*F toaster oven again. Allow the board ~5 minutes to reach 250. OK. 250. Now set your toaster oven to 360*F and set a timer for 10 minutes. We want the temperature to ramp up to and hold 360 with our board in there so there are no thermal stress cracks created from the temperature increase. When this timer goes off set the toaster oven to 420*F and set a timer for 3 minutes. I chose 3 minutes to be safe and mine now works again. Be present during the re-flow process; constantly check on it to be sure there is no smoke or obvious melting of plastic parts. If after testing this hasn't worked for you then try the re-flow process again. Do not increase temperatures or times though. We are getting damn near damaging temperatures at this point (there was slight melting damage to my white plug, nothing catastrophic) so play it safe. When your 3 minute timer goes off, turn the toaster oven off and allow everything to come to room temperature without provocation. DO NOT open the toaster oven and DO NOT remove your board from the toaster oven prematurely as this can cause thermal stress fractures as easily as ramping up too quickly. This would completely defeat the purpose of what we just did.

OK, so you have cooked your board. It is now time to test it. Leave everything exposed still and go out to your car. Turn the radio on to a station you know worked before removing the board but had poor reception at times. Have that playing while you are reconnecting the board. Plug up all 4 connectors. It will likely be necessary to apply pressure to the area of the board that has the spring type connections on the back to ensure these connectors are making contact. We removed the rubber that ensured a tight fit so this isn't unexpected. Have a friend try out your remote while you apply pressure. If everything works better now, great! If not, bad luck. You can try re-flow again and again but like CPR at some point you are just breaking ribs. If you are, like me, lucky then it is time to finish up. I was tempted to use liquid tape to cover the board back up but don't know enough about it and opted not to. Instead, I just used a few layers of electrical tape lengthwise on the board (3 overlapping pieces gently stuck to the board for each layer with perpendicular pieces on the ends to keep the long pieces stuck). This board is inside your car so we are just trying to protect the board from short circuits. Don't get too OCD here. Don't forget to apply a few layers of tape to the contacts underneath the board that were covered in rubber (the gray, tan, white plugs' joints). Once you're content with your less elegant insulation job you are almost done! The last step is finding something you can use to fill the space between the board and the plastic retention clips previously filled by rotting rubber. I used zip-ties. Get the board up there and use a zip-tie tied around each plastic clip to fill the space left by the removed rubber. Test everything and assuming it is all good you're done! Put the cover back up there (make sure the center metal clip is slid onto the plastic cover so that it can apply forward pressure and keep it from vibrating).

That's it! Enjoy not looking like a fool placing your remote against your head for better transmission, unless that's your thing, then by all means continue. I tried to be as eloquent and detailed as possible since I didn't take photos. Please. Please, please, please ask questions. I would rather someone ask a question and not do damage than think they understand what I meant and break their board. I can probably get some pictures if this isn't clear but at this point today I just do not want to remove it again. Hope this worked for you, cheers!

Also, the part number for this is 8E5035225D or 8E5035225S depending on your radio features. Just thought I would make this readily available.