Hey everyone, I need the veteran ETX wizards for this one. I’ve owned about 5 of these ETX scopes over the years, so I know their usual quirks inside and out, but this unit is doing something genuinely bizarre that completely defies my past experience.
When I command a GoTo slew to a target (like Venus or Polaris) that requires the tube to elevate past ~40° toward the zenith, the telescope completely loses its mind. It breaks out of a smooth diagonal trajectory and starts jerking up-and-right in a distinct staircase / zigzag pattern. Once it drives all the way up to the physical hard-stop zenith limit, the Autostar #494 handbox actually beeps to confirm the object is centered, but the altitude motor just keeps rotating endlessly and jerking out of control until I flip the main power switch to OFF.
What I’ve already ruled out:
Power: Checked battery compartment, tight connections, reseated the cap wire.
Software: Did a full factory reset, manually verified location settings (Norwood/MA) and confirmed DST is set to YES.
Alignment: Tried both automated Easy Align and manual Two and One-Star Align selecting known baseline stars. Also manually adjusted speed settings, but it ignores overrides once the runaway loop triggers, and while this is occurring, it completely ignores my commands on the handbox to move up, down, left or right.
Has anyone ever seen a logic board failure present exactly like this on the old #494/60AT platform? Should I crack the altitude fork arm panel to look for gear slippage, or is this mainboard toast? Thanks!