The problem you are having with the Sony PFM500 with error codes 12 and 22 is not the HV power supply. Unfortunately you have an unfixable monitor. Most people hear a "pop" just before the monitor quits and then the error codes appear. The problem is in the plasma screen itself. If you were to remove the large cover from the back and look on the far left side of the plasma screen you will see several epoxy covered areas on the plasma screen ribbon cable. One or more of these areas will have a crack or popped epoxy. There is an IC under there that has catastrophically failed. It is not worth the cost to replace the screen.

Hello, I have the same problem on a pfm-500a3we. If someone have a solution,can you please send me a mail ? Thanks, Nicolas.

I also have the 12/22 error code displaying on my PFM-500A3WU. Can anyone shed some light on this problem, and how it can be fixed? Thank you

i too have a PFM500 but dont see the error code when the red on light flashes. The screen seems to switch itself off. It flashes onscreen first and then off it goes. It then tries to power itself back on - sometimes it stays on and is fine, othertimes it does the same thing again... any ideas? thansk v much :o)