Strong SRT8500 Service Manual page 18

4) Screen ratio problem
If a strange ratio in 4:3 and 16:9 is detected, the voltage of TV scart pin number 8
is below 9V. In case of around 7V, screen will be shown with 16:9 ratio. In case of
over 10V, the ratio will be 4:3. If there is still a fault on screen after adjusting
screen ratio, it means the resistance of R595 on the circuit is not 1K. If the
voltage is normal but the voltage switch does not operate properly, it means that
Q593 TR is not operating normally. In addition, Q592 can affect the problem because
Q592 is a TV/sat transferring switch .
4:3-Low 0V
16:9-High 3.3V
16:9= 6V
4:3=11.3V