Monitor picture collapsing

The next thing I'd do is get the TDA1170 data sheet (it should be on the web somewhere). 99% of designs using that chip follow the same schematic, at least for the output stage, so you should be able to match things up. Then suspect the electrolytics associated with the output stage. One of them might well be shorting... My thought was a fault in the vertical section that (a) completely killed the vertical deflections and (b) loaded the supply to the the vertical section, (from the flyback transformer), enough to much up the horizontal side too. Anothre thought was that the vertical fault caused a heavy current to flow in the deflection coils -- heavy enough to saturate the core and thus change the inductance of the horizontal coils enough to mess up the operation of that side of things. But it's not that either -- if it was, the beam would surely be deflected well off-screen, it wouldn't be in the centre. -tony