Hello.!! Romer is difficult to give an idea of ​​how to face this repair does not give any data of that equipment, I suppose it is to transistors or have the 2 variants of the time of integrated black and white and transistors, and when you say screen in white ie the raster or raster is a smooth white without black dots, that means that there is no sign that the stage of RF is working well if only the noise level of FI is detected, in some models it did not give much level then hardly appears as they usually say "rain", or noise and in the audio too, then you would have to check the tuner voltages and the IF stage and observe especially the level of AGC this voltage determines if the tuner is polarized one of its pins for a correct operation in addition to the others, if it is transistorized and that rotating type or varicap, the first it is easier to detect whether or not varicap is more complex, but to not get into so many better questions some information passes, and if it has technical level to do this repair ..