|
Are you saying that the focus control is at one extreme and the picture still isn't in focus, or that the picture isn't sharp enough even when the focus is set to its optimum position? If the control is at one extreme, you might want to try measuring the focus voltage with a HV probe to see if it should be higher, or lower. That might make it easier to figure out what could be wrong with the circuit. If you can adjust the control to its optimum setting, but it just isn't very sharp, I would suspect a weak CRT. Definitely check the HV is you can because if it's incorrect it will affect the focus. Most CRTs require that the focus voltage be somewhere around 20% of the anode voltage (eg. 5kV).
|