On Sat, Nov 25, 2023 at 11:12 PM Rob Jarratt <robert.jarr...@ntlworld.com> wrote:
> > Have you checked the diodes and capacitors associated with the flyback > > transformer? If something is shorted there. it's the equivaent of running a > > power supply into a short circuit. The input current will go up. > > I have checked all the diodes (in circuit) and they appear to be OK. One > capacitor may be suspect but without the full schematic I am not sure. I may > have to lift it to check. Without the schematic you are going to have problems. With a schematic you can see (a) Can you isolate certain areas -- for example the vertical deflection syste > > Trace out a schematic of the board so I know what I am dealing with. > > Yes, I may have to do that. Historically I have done a poor job of this > because of my insufficient understanding of electronics. It gets easier with experience. Looking at every small monochrome monitor schematic you can find will give you an idea of the sort of things to look for. > > I do wonder what the problem is with testing it with the flyback connected, > > though... > > Only that I know it can produce lethal voltages and I would rather avoid that > if I can. The high voltage outputs can't supply that much current and are unlikely to be lethal. Mains, and even worse the rectified mains in an SMPSU, is a lot more liely to kill you. That said, work with one hand in your pocket (current flow arm-to-arm is the most dangerous) and take care. I don't see how you can debug a monitor without having the flyback in place. It's part of the highest power circuit on the board. And it provides voltages for many other areas. -tony
