The picture is slowly closing in from the top
and bottom. I have changed PL83, PL81 and PCF80 in turn in the hope that I could open the picture, however, this has made no difference. If lack of width should occur at some time, could you please tell me what might be the possible cause?-G. Ibbs (St. Neots, Hunts.). There are so many variations in the chassis
likely to be encountered in your receiver that it is
difficult to give specific advice. Check the screen
grid and cathode electrolytic decouplers of the PL83 (if fitted) and check the boosted h.t. line which supplies the ECC82 oscillator valve via the vertical amplitude control. A first anode lead on
the c.r.t. can produce a low boosted h.t. line. Lack of width is usually due to low h.t. caused
by a faulty h.t. rectifier.