There is a permanent ” buzz ” on the sound which comes on as the picture appears after the
set is first switched on. This is present on all
channels including u.h.f. and cannot be reduced by use of the ” anti -buzz ” control on 625 -line
working. Operation of the volume control does
not affect the buzz.
Another sound fault on this set occurs when- ever a light switch is operated. When this
happens, a flash appears across the screen, a loud
click is heard from the loudspeaker and the sound
level generally becomes very loud. After a while
the sound returns to its normal level.-D. J. Mundy
The first fault may be due to frame timebase pick-up on the lead from the sound output valve
anode to the sound output transformer. This lead
should be screened.
Volume variations are usually caused by a
faulty 25µF electrolytic in the cathode circuit of
the sound output valve.