I come to this discussion exactly as Music Manager did... A novice, wanting to learn, choosing the Chinese PSU kit, thinking it was adequately engineered... discovering that the kit has problems, wanting to fix its issues, and by it all, frustrated. I have read the thread some several times, but I don't think I am following the instructions correctly...
I thought that the corrections to make the kit operational were summarized on Post #34... Accordingly, I have made those changes... However, as I look back through the thread, I think I may be seeing additionally needed changes. Audio Guru, would you please make a single, complete list and schematic for me?
I have a 24vac, single secondary transformer. It is producing ~25.5vac from 110vac/60Hz mains. That's about 32vdc, as I recall, after the rectifier.
I am shooting for 0-30vdc and 0-3amps... I ended up with multiple sets of kits, due to shipping errors. The first kit I assembled, without any changes, was producing the target numbers, but with overheating. It appears that a 28vac transformer maybe suggested...
Additionally, I will be changing the fan voltage regulator to a 7812. I have a 40mm fan and heatsinks for cooling...
The 12K cap is huge... I will bodge it onto the bottom side of the PCB...
Thank you for your help!