RE: U2412M, Repair a defective diode
thank you so much for posting this, you saved me so much time. I had exactly the same problem and after quickly checking the UF5404 diodes I found out both were defect (the same as marked in Jeremy's picture). Without you I would have checked every single diode, since I only have a multimeter. After exchanging them the monitor runs fine again.
You Sir deserve a medal.
Thank you again for your help