The symptom is that the Compu-Dobby will on, rare occasion, not advance to the next pick. The failure to advance occurs randomly, but typically once every several hundred picks. On older Compu-Dobby IV & 4.5s this may appear as the next lift will lift nothing (positive dobby) or all harnesses (negative dobby). With newer Compu-Dobbys the error will manifest itself as the next lift will repeat the last lift for both positive and negative dobbys. The electronic noise originates outside the Compu-Dobby on the USB line or interference induced on the sensor lines.
AVL has released new firmware that reduces the chance of noise affecting Compu-Dobby operation. The new firmware uses more advanced error avoidance techniques and theoretically reduces the chances for errors by at least an order of magnitude. In practice, the new firmware appears to altogether eliminate the errors as we have not encountered the error after many thousands of picks.
How to Upgrade
If your Compu-Dobby IV has never exhibited this issue, we do not recommend updating firmware at this time. For those that have observed the issue, you will need to send us either the processor or the Compu-Dobby for updating. AVL will perform the firmware update for free, but the customer must pay for any shipping related costs. Please contact AVL technical support here to receive return authorization prior to send anything to AVL.
Compu-Dobby 4.5 and Little Weaver customers may update their firmware using AVLUpdate and by downloading the latest version of the firmware from the AVL website in our library, with a direct link to the download here. Please note that all Compu-Dobby 4.5 sold after August 2016 have the newest firmware already installed.
There are two compatibility considerations for this update. WeavePoint requires version 188.8.131.52 or newer and Fiberworks requires version Silver 184.108.40.206 (PC) or Silver 1.2.3 (Mac). Please contact AVL technical support to update WeavePoint, and Fiberworks directly to update Fiberworks. All versions of AVLDrive will work with the new firmware.