All that is available on the screen is a reddish hue, or reddish white. On a monochrome transmission the reddish hue is still there. Adjusting the user controls makes no
difference to the fault.
Checking the c.r.t. electrode voltages should indicate the
cause of the trouble. If the grey -scale doesn’t alter when the
drive and background controls are adjusted, the c.r.t. is
faulty. It seems to us more likely however that the trouble is
in the red drive circuitry. If the voltage at the collector of
the red output transistor Q702 differs appreciably from that
at the collectors of the green and blue output transistors,
Q702 is suspect, along with the R-Y emitter -follower transistor Q157. If all three colour output transistor collector
voltages are about equal, try setting up the grey -scale as
described in the manual.