Most likely suspect?
 

I have an old Sony SLO-325 Industrial Beta VCR that I have been
restoring. It works well, but only after it has been powered up for
30-45 minutes. Started cold, the audio is OK but the video is complete
noise. After 30-45 minutes, the video returns in perfect color without
noise. I suspect a bad capacitor somewhere in the power supply, but
could something else explain the need for such a "warm-up" time?