BUSH TV161 SERIES
Once the picture has come on the field starts to run at a
very fast speed. After a further four minutes or so the set
will lock, remaining stable except on very dark scenes.
A failing PCL805 field timebase valve
is the most
common cause of this symptom. Other possibilities are: the
interlace diode 3MR3, the
field sync pulse coupling
capacitor 3C29, and the PFL200 video/sync valve and its
associated screen grid and cathode decoupling electrolytics
2C48 (8,uF), 2C44 (10µF) and 2C45 (320,42F).