THORN 8000 CHASSIS

The picture has always been too wide – half the last square
at each side is lost. I’ve tried juggling with the scan coils (at
the expense of purity) and adjusting the set e.h.t. control in
the power supply. As there’s no width control, it looks as if
modification will be necessary. Any suggestions?
We would not advise modifying a solid-state line output
stage: the whole thing is carefully designed, with resonant
circuit action, and unofficial modifications would be likely
to result in component failure – which could prove expensive.
The width is related to the e.h.t., which may be low –
the higher the e.h.t., the smaller the picture. Make sure first
that this is set up correctly. Then if necessary check the
following capacitors by substitution: C406 (flyback tuning)
0.0015µF; C444 (a.c. coupling to the line output
transformer) 0.47µF; C407 (scan -correction) 0.68µF. Any
replacements should have the same value and ratings as the
originals, and preferably be Thorn approved parts. The
other (unlikely) possibility is a faulty line output
transformer.