If you saw A1F7, then that is the preferred firmware for the LXD75 and
it means you have an Audiostar handset. No update required yet.
The fact it starts running at full speed in RA normally means that something is wrong
with the encoder feedback.
ie at that part of the process, the mount starts tracking, and if the encoder loop is faulty
the motor wil run up to ful speed trying to get feedback.
As its an open encoder, this could be due to a bad calibrate or it might be a faulty encoder.
What you can do is unlock the RA clutch
Start the mount and mode through the menus.
If it starts running, just leave it, as when declutched, nothing will get hurt.
Go into the "Setup > Targets" menu and set it to "Terrestrial"
That will stop the motor running.
Now go to "Setup > Telescope > Calibrate Motor" and run it
This will spin both motors for a few seconds to reset the encoder LEDs
Now try "Setup > Targets" menu and set it to "Astronomical"
If it starts running away, set targets back to Terrestrial
Now go to the "Setup > Telescope > Telescope Model"
Select a fork type mount, doesnt matter what type, but an LX90 is good
Now go to the "Setup > Telescope > Mount" and select Al/Az
In this condition, you can always start the mount for testing
and the motors wont start, so see if you can get that far
Andrew Johansen Melbourne Australia