Long and sad story...
The cab has a switcher plugged in and was running ok on that but I wanted to get it back to the original power board but that had problems with the voltages. I bought a lad of caps etc and set about doing my first ever repair, seemed to go ok, turns out I am quite good at soldering. Tested the voltages on the test points nd all were fine and the 3 LEDs were lit up so plugged it in and started the cab, get a rug pattern on the main screen which doesn't go away. Decide to check the voltages again and manage to short something out and blow one f the fuses, got annoyed and have decided tht if I can't fix it then I my as well get a new one...
The cab runs fine off the switcher although it seems to have a little graphics distortion at the moment hich is. Problem for another day!