My SLT telescope slews erratically and it's not locating objects. What can I do?

If your NexStar SLT scope isn’t performing well, you can try the following three steps yourself.

First, check the power supply. Fresh batteries in a clean holder and all wires are in good shape. Or switch to a PowerTank or similar external DC supply. Try an AC adapter that is a Celestron-recommended 12V DC, 2.5 amp output, tip positive source. For any external source, be sure the power port on the scope is clean and the pins in the center are slightly spread ensuring good contact with the car battery or AC adapter jack. Check the car battery adapter itself. Check AC extension cords and wall plugs.

Second, reset to factory settings by using Utilities > Factory Setting. This will put the hand control back to its default settings.

Third, reflash the hand control and motor control firmware. Download to your PC and install the HCUpdate and MCUpdate programs from Using the RS232 cable and your PC, connect your scope through the hand control and run the update software either replacing your current versions of hand control and motor control firmware or upgrading to the latest versions.

If none of these work, most likely your mount and hand control need Celestron factory service to restore proper function.

Updated 12/27/13