How to repair AFM

[Kibokojoe]

Well I crack open the AFM and moved the board around cleaned the contacts and now she is working. Prior to this repair I got no ohms reading on pin 2 and 4 now it swings smoothly between 45 and 800. Here is my instuctions. Hope no one is color blind



Carefully pry open the plastic box on the bottom of the AFM. I used an exact-o knife to score all around the box and then used a sharp screwdriver to slowly open the box. The reason there was no ohms reading was that the contact arm had scratch all of the resistance material from the circuit board. If you look closely, you will see the two arches with scratches. First thing is to remove the contact arm by removing the Philips screw just left of the white arrow. Make sure to mark where the arm is located. I used a pencil and marked just right of the end of the two white arrows on the circuit board. Now remove the arm. Using a q-tip and contact cleaner clean the area with the scratches and also the contact points on the arm at the two white areas and the single white arrow. Now remove the screws at the red arrows. The one screw on the left has already been removed so you can see the epoxy they used to fill the hole. The epoxy was used to keep the circuit board from moving. Now using a small flat screwdriver remove the epoxy from all of the holes. Be careful and don’t move the circuit board too much the wires at the yellow arrows and running down to the green arrows are very soft and can break easily. I had to re-solder the one on the left you can see the flux on the contact. This was a real pain to get to stick. I cleaned and cleaned and it finally stuck. While you have the board loose carefully shift the board so you can clean with the contact cleaner under the brass and silver contactors at the end of the green arrows. Now slide the board as far as you can in the direction of the blue arrows and reinstall the screws. Now install the contact arm being careful to realign it to the pencil mark on the circuit board. You will see now the contact arm is rubbing on the contact arch in a different place. Apply the silicone where the purple arrows indicate this will keep the circuit board from moving.

Time to close up: Now apply a very thin continuous ribbon of silicone in the plastic box groove and place the box back on the AFM. Place a weight on the box and let it sit over night.

[Kibokojoe]

Since repairing the AFM performance is improving and I don't have the stuttering on accelleration anymore Awesome.

[shogun]

good one, here more info to have it all concentrated in one thread
http://paulaxford.com/bmw730i/afm_service.htm

[Kibokojoe]

Yes Shogun sent me your site after I made the repair. Would have been nice to have it before I opened it up. Reguardless you site has a lot of good information and I have borrowed several pages for future reference

[genphreak]

I've done the same before, can attest it works if you take appropriate care.

Best and simplest write up I've seen on the good ol' AFM mate... good work!

[Kibokojoe]

Thanks