Cleaning and overhauling the AFM...
 

... Is what I've been doing today. :)

I followed the details on this page:

http://www.the944.com/afm.htm

I decided to do this as I wondered if the reason I get intermittent response issues when I start to accelerate in the higher gears may be down to the metering being off a little.

It's pretty straightforward to do - the hardest part is popping the black cap off the top of the meter, but once you've got it off you'll see this:

http://greatoldone.squarespace.com/s...internals1.jpg

Taking off the rotor arm to clean it is just a case of slackening off the 7mm clench bolt on the back of the assembly. Then it slides off the shaft, and you can clean the potentiometer track

http://greatoldone.squarespace.com/s...internals2.jpg

A you can see my meter had some well worn groves in it.

http://greatoldone.squarespace.com/s...internals3.jpg

Once I'd cleaned everything I reassmbeled with the rotor arm positioned higher up and the contacts arms bent slightly down, moving the sweep in toward the centre of the meter

http://greatoldone.squarespace.com/s...internals4.jpg

I've checked the operation and i get a nice smooth response from the potentiometer. I also checked out the temp sensor in there as well, and it's fine.

Now all I need to do is seal the lid back on and fit it back in Vikki.

Nice, just don't play with the tension, I totally screwed my original one up doing that!

Nice to see some old 1980's thick film technology in action!
IIRC the conductors and resistors were screen printed on a ceramic base before being fired in a kiln and then laser trimmed to the correct values.
Did the Bosch AFM really need such precise resistor values? :noidea: