Short Circuit Between The Screen (G2) and the Control Grid (G1)


Dear Jestine: I have a very interesting question about whether we can use the same method of blowing away a short between the focus grid and the screen grid and apply this method to the shorts that can happen between screen and control grid or for example or the control and cathodes .....if so then I would use it to increase the possibilities of saving a CRT tube bye for now. Wael Fathe


Dear Wael: If the CRT screen grid (G2) and the control grid (G1) shorted internally it could cause the Monitor to have no display and even if have display it will going to have bright display with white flyback lines across the screen diagonally. The method that I had shared to all of my ERG members was to remove the shorts between the screen (G2) and the focus grid (G4). To answer your question, yes there is a possibility that you can use the same method to blow away or remove the shorts between the screen and the control grid.


However there is a risk because the control grid (G1) is located very near to the RGB cathode. In other word, if you use the method on this screen and the control grid, I’m afraid you may blow away a good RGB cathode (cathode material drop out from its location because of the high voltage across it) or even causing short circuit between the control grids with one of the RGB cathode. If this happens the Monitor will be going to have a missing color or even a bright display with flyback lines across the screen.


There is no harm trying it, after all the CRT is already confirmed to be not working. Let your customer know first the consequences before begin to blow away the shorts. If you have a ready spare tube for replacement I suggest you to try it, who knows the short might be removed with just a single discharge!