I've reverse engineered the horizontal deflection and HV circuit of a common Chinese B&W portable CRT TV set. The end goal is to come up with a robust and reliable HV board for my 5" vector monitor project that uses the CRT from one of these sets but in the process I'd also like to fully understand how the existing circuit works and expand my knowledge in the area of SMPS design.
Anyway looking at the existing circuit, am I correct in thinking this is a L-C-L resonant tank with the flyback primary, C1, and the horizontal deflection yoke? What is the purpose of the arrangement with D1 and C9, and also C8, C10 and D2?
Now I wired up the circuit outside of the TV, using a mosfet in place of the original HOT and it works fine. Actually being built on a copperclad ground plane the waveforms look significantly cleaner than they do in the TV. What I'd like to do though is achieve the same result without needing the large inductance provided by the yoke, better yet if I could get away with no separate inductor at all. Driving the flyback transformer alone I was able to get about 5kV on the anode using a 12V input but that was pushing the duty cycle up quite close to where it seems the core would saturate and input current shoots way up. Any experts care to weigh in and nudge me in the right direction? I've done plenty of HV experiments driving flybacks but normally I'm trying to get high output, here I'm more interested in stable output, long term reliability and reasonable efficiency. Also if at all possible I would like to utilize only the original windings in the flyback instead of adding any new ones to the core.