There is a minor known bug in firmware V1.40 that sometimes causes displayed signals to "jump" around on the screen when very long time scales are used. The bug shows up on 5-Series B scopes when the following conditions are met:
- The horizontal (time-scale) axis is increased far enough that the scope enters "roll mode," where signal traces slowly progress toward the left side of the screen as data is captured
- Firmware V1.40 is installed
This is fixed in the next firmware update, but in the mean time, the issue can be addressed either by keeping the scope out of roll mode (use a smaller seconds-per-div time scale), or revert the scope to firmware V1.38.
Firmware files can be found by going to tek.com, clicking "Download" in the green pull out tab on the very right side of the screen, and searching for your instrument. Or, for MSO 5-Series B files only, you can find them by going to the
instrument's webpage and looking under the "Technical Docs" tab.