Originally Posted by Alaindor
In your opinion, any influence of an UPS wave form output? Square wave vs. sine wave? Could a square wave output create harmonics and increase ripple?
Using a sine wave form output from my UPS, I see no scan lines.
First let's look at what's happening when a pure Sine wave of amplitude 230V of 50Hz is input the acer adapter: This below image is what is happening.
(on a second oscilloscope)
All the energy of that single Sine wave (230V, 50Hz) has been distributed to many sine waves of many frequencies which when summed up form a DC signal of 19.5V for the most part. But the energy distribution is not perfect and some sine waves that should not have been amplified were and so that results in this nice sawtooth ripple waveform (with fundamental frequency of 6.66Hz) added on top of the pure DC of 19.5V.
The case of trying to visualize what happens when a Square wave (230V, 50Hz) is input to the adapter gets complicated quickly. A square wave itself is made up of the sum of infinitely many sine waves (a fundamental sine of 50hz + harmonic sines at 100Hz, 150Hz... inf) of differing amplitudes. (Fourier series
We only know concretely how the adapter behaves to a frequency of 50Hz. But my guess is that the higher frequency harmonics of the Square wave (higher multiples of 50Hz) get attenuated by the adapter and we will end up with a squiggly version of the sawtooth waveform in the picture above (+ the DC ofcourse). Nevertheless, the frequency of the new sawtooth output will still be 6.66Hz and it's amplitude will still be around 300mVp-p. So, the ripple amplitude will still be high. (Take this guess with a huge pinch of salt. If I get the time, I'll edit with a better explanation.)
But if it is the case that your adapter is different than what others have been given, then with either a square wave or sine wave input, your Vpp ripple should be low enough not to interfere with the normal monitor operations. So, if I could get the part number of your adapter (pic of the sticker), we can check if we have the same adapter model. It is possible that ACER sent out bulk orders for 19V,7.1A adapters to different manufacturers and one of the manufacturers is creating these crappy adapters with high ripple. Acer only puts their sticker on the adapter.
PS: I wear glasses too. I spoke to two trusted engineers who are also my colleagues who are much more experienced than I am. They are also at a loss to explain how an adapter can have 300mVpp ripple. Once more, this does not mean that the adapter is causing scanlines, only that the adapter is really crappy. Whether Acer engineers designed the monitor electronics around it remains to be seen.
Originally Posted by Mikey-
Somebody's going to have to interpret for me what Mountainlifter just said? Whoosh.
However they should if they've read your posts above. Glad to have you here at the forum.
I've put up a picture showing ripple in my writeup. Does that help? Basically, I am saying the power signal is "unclean" and not clean enough for a monitor.
Thanks. I'm glad I could add to the discussion.
Originally Posted by Sketchus
Thanks for all the work you're putting into this. Really appreciated.
@Mikey- My adapter part number is "ADP 135KB T"Edited by Mountainlifter - 11/17/15 at 7:06am