PYE 691 CHASSIS

Shortly after the picture appears, the brightness increases.
Two or three minutes returns to
normal brightness, but a convex margin appears on the lefthand side of the raster with some vertical stretching when the picture contains much blue. The performance is
otherwise well up to standard.
The PL509 line output valve or the PY500 boost diode
may be ageing – both may need replacement. Alternatively,
suspect the beam current limiter control of having altered.
To adjust this according to the book is involved. If you note
the present position however and move it slightly either way
no harm will befall. Try for a position giving less width
variation with a dimmer picture.