Sony UVW-1800 Operating Instructions Manual page 20

When this unit is being used, a composite video signal, synchronized to the signal
being used must be input to the REF. VIDEO INPUT connector to enable the time
base corrector (TBC) to operate correctly, and ensure stable operation.
If no reference video signal is input, then during recording or editing, or in EE
mode the monitor screen will tend to drift vertically, as shown in the figure below.
With reference video
The monitor screen and the time counter display also show alarm messages.
(Example: When the VIDEO 2 (SUPER) OUTPUT connector is used with the
"REF. ALARM" set to ON in the menu.)
Monitor screen
During playback, a monitor picture is normally stable without a reference video
signal input.
For details of changing the menu settings, see the section "Menu Operations" (page 7-
8(E)).
No reference video
Chapter 3 Preparations 3-5 (E)