just trying to figure out how the donut, hv coil of a typical flyback for lets say a ctc12-15 is wired. if the donut shorts internally the wax runs off then thats it , finished but if i were to have had a flyback with a bad secondary and another with a bad primary and wanted to try to put the good hv secondary, donut on the fly with the good primary to make a good complete flyback then my question is removing the donut would break the end connection but where is this connection. a secondary like the donut is a coil and when its wound there is a beginning and the end would be to the hv rectifier. where is the beginning wired to, would this be chassis ground or would it be to some connection on the flybacks primary section. i would have thought it would go to ground but not sure being as a coil like this developes hv by inductance so it needs to have a beginning connection to complete the coil to have hv at the other end. just wondering if anyone knows this because im sure there is no book or guide to show how a flyback is made in detail or an original print from an engineers or designers design.

The bottom of the HV (secondary) winding is typically tied to the top of the primary winding (autotransformer connection). This should be clearly visible in the schematic of the set.

Physical construction will vary with the maker, time period, and sometimes the individual model. If you want to make two bad flys into one you have to accept that you may still end up with two bad flys in the end.

HV winding shorts can sometimes be cured....The user here that goes by Shango66/Boxcarcabin has a video on youtube where he fixes one. He explains the rubber tire that insulates the outside of the HV winding can become conductive and become a path for arcing, then the paper winding insulation underneath begins to carbonize and become conductive. On one that failed He stripped the rubber scraped off the carbonization on the paper, and then dunked the fly in a pressure cooker full of molten wax, sealed the modified lid and used a vacuum pump to draw a vacuum....The result: he was able to reinstall the fly and it worked.

yes i heard of that video but never seen it and shango66 is ctc17 from here on karma.