I had the EY51 changed and both the PY81
and PL81 tested, but were found to be perfect. On switching on I get the line whistle, but it
fades away before the picture builds up. If I take the top cap off the PY81 I get a very good spark and brilliance, but the picture has no fine or horizontal hold. On replacing the cap of
PY81 the line transformer immediately goes dead. -G. Metcalf (Halifax).
It is very strange that the act of removing the
PY81 top cap can restore working of the line
timebase. Normally this would stop it as the circuit would then be broken. In view of this
you should suspect the .5 RE capacitor (C68) wired from the H.T. line to the boosted H.T. line.