After more than 3 years of 24/7 operation my DP-558 is also malfunctioning. My symptoms are similar but not exactly as the ones described here. The 558 is not dead but when I watch a recorded show everything works ok for 5-10 minutes. Then the image starts to deteriorate and after a few more minutes the 558 is dead. If I turn it off and restart it it later it does the same thing again. I opened the case and looked at the caps but could not see that any of them were defective. Nevertheless I (or rather my friend who is more handy than me...) replaced C15, C19 and C20 and a few of the other ones. But no improvement.
Just for fun we measured the temperature in different parts of the PSU and it seems that the coil that can be seen on the upper right below the text "REV
" becomes very hot and at temperatures somewhere around 120 C the 558 dies.
Do you think replacing all the other caps will fix this or is it something else that is causing the excessive heat?
Thanks for any help!