Shitty PSU? Agreed. My redesign addresses all the issues.
Papa Smurf I am wondering, about the 5V rail redesign.
I am wondering why you didn't simply add the 7805 and call it a day ?
You replaced the original two-diode / center tap full rectification with a full bridge diode, which forced you to use only one of the two windings.
So now that winding has to supply twice the current it was designed for, no ? I am sure it works fine in this particular case since you did it, but you didn't know it could take it... it might overheated and blew a head gasket or something.... at the least it's way overloaded so it's not being nice to him.
Also, you halved the value of the capacitor, so more ripple. The 7805 is probably able to make up for that, but why not just leave the cap at its original value ?!
Why not have simply kept everything original hence safe (for the transformer windings) and in spec (ripple wise), i.ie simply leave the center full wave rectification and 4000uF cap in place, and simply add your 7805 after that ?!