Strange buzzing from LCD monitor

F

Franc Zabkar

Guest
If I use Windows Notepad to view a text file consisting of the letter
"a" repeated ad infinitum, my Mitsubishi Diamond View DV152 15" LCD
monitor buzzes noticeably. The same buzzing occurs with other
repetitive patterns. I have noticed that bold face type is louder, and
that shrinking the notepad window progressively reduces the sound
intensity. I wonder if this is normal, or is a sign of impending
problems with the inverter or power supply.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
Possible noise from the power supply when the load is increased. Does the
noise come specifically from the lit display, from the base, or rear of the
unit?? May want to try an place the unit on a soft surface such as a mouse
pad and see if the noise is mitigated??
"Franc Zabkar" <fzabkar@optussnet.com.au> wrote in message
news:0hkq10dtsd43ngbp6fvcfgihpiie61o6ui@4ax.com...
If I use Windows Notepad to view a text file consisting of the letter
"a" repeated ad infinitum, my Mitsubishi Diamond View DV152 15" LCD
monitor buzzes noticeably. The same buzzing occurs with other
repetitive patterns. I have noticed that bold face type is louder, and
that shrinking the notepad window progressively reduces the sound
intensity. I wonder if this is normal, or is a sign of impending
problems with the inverter or power supply.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Click to expand...
 
On Sun, 1 Feb 2004 14:45:51 -0500, "Art" <stubby@comcast.net> put
finger to keyboard and composed:

Possible noise from the power supply when the load is increased.
Click to expand...
I notice that the noise does not change if I press the "Auto" button
on the monitor. This blanks the screen and brings up a small
calibration message box at the centre. It appears that the noise is
related to the video content in the signal, not to the actual screen
display.

Does the
noise come specifically from the lit display, from the base, or rear of the
unit?? May want to try an place the unit on a soft surface such as a mouse
pad and see if the noise is mitigated??
Click to expand...
I didn't realise it before, but the noise comes from the monitor's
built-in speakers. Adjusting the volume setting alters the sound
intensity. Very strange!

"Franc Zabkar" <fzabkar@optussnet.com.au> wrote in message
news:0hkq10dtsd43ngbp6fvcfgihpiie61o6ui@4ax.com...
If I use Windows Notepad to view a text file consisting of the letter
"a" repeated ad infinitum, my Mitsubishi Diamond View DV152 15" LCD
monitor buzzes noticeably. The same buzzing occurs with other
repetitive patterns. I have noticed that bold face type is louder, and
that shrinking the notepad window progressively reduces the sound
intensity. I wonder if this is normal, or is a sign of impending
problems with the inverter or power supply.
Click to expand...


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
"Franc Zabkar" <fzabkar@optussnet.com.au> wrote in message
news:l3nq10d70la9ka6on63u1kr2c2a18lu3ak@4ax.com...
On Sun, 1 Feb 2004 14:45:51 -0500, "Art" <stubby@comcast.net> put
finger to keyboard and composed:

Possible noise from the power supply when the load is increased.

I notice that the noise does not change if I press the "Auto" button
on the monitor. This blanks the screen and brings up a small
calibration message box at the centre. It appears that the noise is
related to the video content in the signal, not to the actual screen
display.

Does the
noise come specifically from the lit display, from the base, or rear of
the
unit?? May want to try an place the unit on a soft surface such as a
mouse
pad and see if the noise is mitigated??

I didn't realise it before, but the noise comes from the monitor's
built-in speakers. Adjusting the volume setting alters the sound
intensity. Very strange!


Perhaps a bad capacitor in the power supply is allowing excessive ripple
Click to expand...
into the voltage to the audio amp.
 
LCD's have shit amps for the speakers. (they pick up way too many RF
signals.
 
In article <l3nq10d70la9ka6on63u1kr2c2a18lu3ak@4ax.com>, Franc Zabkar
<fzabkar@optussnet.com.au> writes
On Sun, 1 Feb 2004 14:45:51 -0500, "Art" <stubby@comcast.net> put
finger to keyboard and composed:

Possible noise from the power supply when the load is increased.

I notice that the noise does not change if I press the "Auto" button
on the monitor. This blanks the screen and brings up a small
calibration message box at the centre. It appears that the noise is
related to the video content in the signal, not to the actual screen
display.

Does the
noise come specifically from the lit display, from the base, or rear of the
unit?? May want to try an place the unit on a soft surface such as a mouse
pad and see if the noise is mitigated??

I didn't realise it before, but the noise comes from the monitor's
built-in speakers. Adjusting the volume setting alters the sound
intensity. Very strange!

It must be the audio amp picking up interference from the VGA cable,
Click to expand...
when your video signal has lots of transitions from black to white.
Probably down to bad screening inside the unit or interference getting
through on the power supply to the audio amp. Solution: use some
external speakers.
--
Tim Mitchell
 
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