Quote:
Originally posted by lendaddy
Thanks Nick, this does not have an exposed area. It is encased in clear epoxy and all you can see are two metallic pads with three brass pins on each side (again encased in epoxy) We have been playing with the spacing so you're right on with that idea. The funny thing is that it will read the scale smoothly but will not find the registration mark (when you "home" the drive it needs to find this reference point so it knows where zero is). I have double checked all connections and that has me believing that by wearing through that epoxy we have damaged or contaminated something.
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Len, this doesn't sound like a problem with the reader head being worn out, especially if it is functioning properly except for the homing. I would guess that there is a separate electrical path that is supposed to trigger when the registration mark is found. I would suspect a broken solder connection on a pin.
My guess is that the sensor is a hall effect. This would produce a small signal pulse when the reader passes over the reference mark. This needs to be amplified for processing. All of this would be the same for the other read process, I suspect. My guess is that there is some special output line that is reserved for the zero reference. This would be on one of those three boards and feedback to the machine.
You don't happen to have any schematics? It would be possible to suggest some things to check if you have this.