Hello everyone , I have in front of a LED sign which is powered by a linear power supply, transformer + diode bridge and capacitor The measurements I made hot are: 230v AC transformer input diode bridge input, ranges from 20 - 27 volts AC. diode bridge output, ranges from 22 - 36 volts DC capacitor of These measurements are loaded and the oscillations are quite fast and I relate them to the LEDs changing state very quickly and many flashes. The rest of the circuit consists of: a voltage regulator at 5v DC, (does not have any reference registered) but regulates at 5v stable and are to power the processor (without reference) that controls all state changes Through two ULM2803 that give way to the voltage, the diode tip output (before passing through the capacitor that acts as a filter) and feeds the LED strips Well this is the summary of the circuit. when I got to my hands I had a short ulm and several cracked welds, I changed and solved all the welds I saw cracked and overheated, and it works fine but ..... when it has been on for a long time, the LEDs go out. If I have it on without closing the structure where it is mounted, it never goes out and works well even if the transformer gets very hot and the diode bridge too. but everything mounted in its box goes out, sometimes it only takes a while, sometimes it takes an hour or more, the problem I have is that I cannot measure hot where the power is cut off, since in what I open it and remove the led strip to access the card it already works again, what do you advise me ?? Where do you think the problem may be? So many voltage oscillations are normal in this type of source? Thank you and I hope your wise advice.