My old thread on swapping out the resistor in a Mk II tach to make it work with an AAZ might be what the OP was mentioning in the first post.
http://www.vwdiesel.net/forum/index.php?topic=12589.0Thanks again to both fatmobile & regcheeseman for all their help with that.
The 13k resistor was swapped for a variable resistor set to about 8.2 k.
adjusting the bottom left potentiometer brought my rpm down its still slightly high a but its a hell of alot closer now. thinking about putting my own potentiometer in places of the original.
You can try but in my experience the chip (SAK215) can't cope with such a short sample cycle and just shuts down when you start to rev the engine - it'll recover though, so no harm done.
What's different with the SAK215 chip in this tach, relative to the chip in the Mk II tach? The variable resistor swap in the Mk II tach worked a treat.
