Strange one, a squegging PSU!....
All's well for about 10 minutes. Then the sound starts to break up, chopped, making everyone sound like Mahars from the old sci-fi film, At The Earth's Core but the picture remains fine.
While fault-finding it was noticed that just occasionally the backlight would blink off. This got worse and worse over about 15-20 minutes to the point it was flickering rapidly, like a Strobe--and in time with the sound....
Scope checks of the 24V rail of the PSU showed it was dropping to about 15V on a very regular square-wave of about 4.5Hz, then back up to 24V....
Most the other rails were doing much the same--except the ever 5V Standby supply which was reasonably clean--but 7V, measured at its rectifier....
The set has only 83 hours on it, no poor caps, nothing obvious, and a replacement 17PW26.4 (the sorta 'PFC version' of the 17PW25.3/4) cured the problem.
All's well for about 10 minutes. Then the sound starts to break up, chopped, making everyone sound like Mahars from the old sci-fi film, At The Earth's Core but the picture remains fine.
While fault-finding it was noticed that just occasionally the backlight would blink off. This got worse and worse over about 15-20 minutes to the point it was flickering rapidly, like a Strobe--and in time with the sound....
Scope checks of the 24V rail of the PSU showed it was dropping to about 15V on a very regular square-wave of about 4.5Hz, then back up to 24V....
Most the other rails were doing much the same--except the ever 5V Standby supply which was reasonably clean--but 7V, measured at its rectifier....
The set has only 83 hours on it, no poor caps, nothing obvious, and a replacement 17PW26.4 (the sorta 'PFC version' of the 17PW25.3/4) cured the problem.
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