I found an old CRT TV set in the garbage. It didn't work, always showing the "snow effect", even when I connected it to another device via the SCART port.
So I followed an online tutorial to make it into an oscilloscope. However, I encountered some problems. I'd like to know if they are likely to be resolvable or not, since I'm not an expert in this field.
There are four connections for the CRT that should control horizontal and vertical deflection. I disconnected the wires that control horizontal deflection and connected in their place those that previously controlled vertical deflection, in order to have a horizontal line at a scanning frequency of 60 Hz. Then I connected two wires for controlling the vertical deflection (at the other end of these wires I can put an audio output or just a battery). When these two wires are not connected to anything I should see a horizontal line.
What happens is that the horizontal line that should appear like a solid bright white line appears instead as a weak reddish line, as you can see in this picture:
The strange thing is that I tried with a friend to connect and disconnect the four wires to the CRT when it was powered on and, apart from the sparks, the process of connecting and disconnecting those wires resulted in a white bright line as it should be.
Even when all the wires for horizontal and vertical deflection are disconnected a weak red point appears and only with active manipulation performed when the device is on I manage to see a bright white dot instead.
I'd like to know if this behavior is due to the TV set being defective and is not easy to repair, or if it is somehow my fault and it is easily solvable.