Whining from Xerox monitor

[tom66]

A year or so ago, I got a nice 19" 4:3 LCD monitor from my brother, which was not working. (It would display a Xerox logo briefly, then fade white.)

I found it had 7 bad caps and replaced them with Chemicon KY and Panasonic FC. It's worked great ever since.

However, I've recently noticed a whining from it which changes pitch with screen content. To my untrained ear, this sounds like the PSU is unable to keep up with the load the T-con is demanding, as most LCDs use more power to make pixels dark than light (right?) I had heard this whining with LCD TVs and it is common with bad caps.

Could my new caps be failing? I'll probably open it up when (if) it fails, but has anyone else heard (pun intended) of this problem before?

[budm]

Re: Whining from Xerox monitor

I would check the DC and AC reading with meter on that large DC Main filter cap. The DC should be steady, and AC (AC ripple riding on the DC) should be real low. Check it with monitor OFF, ON, min and max brightness.