Hello,

My sony TV KV2764EC has an E/W problem. The circuit is based on a TDA1082
and thyristor S6344G.
I never came accross such a setup. The E/W corrections I know all use a
transistor as end stage.
I read that the TDA1082 can work in class A where the output is a parabola
fed to an end transistor,
or as class D where the output is pulse width modulated coupled to a FET and
then filtered.
According to the datasheet, TDA1082's pin 4, when used, produces a class D
amp, but pin 4 is not used in the sony
so it should be a class A.
I have a real problem to understand how this e/w stage with thyristor really
works. Can someone explain?
Now practically, the E/W module resides on a printed circuit board. I
replaced the TDA1082, checked all capacitors
(also for ESR) on the board and all resistors and they measure OK. The 12V
to the TDA1082 is also OK.
The signals to the board were checked with a oscilloscope and compare to the
drawings.
I measured the thyristor and it also looks healty (no short between a/k and
100 ohm between g/k) .. but it was not replaced yet.
Width cannot be adjusted and E/W just a tiny bit .
If any ideas, thanks beforehand to share them with me.


Marc