I have a gateway LCDFPD1730 that makes a hiss or Hum when it is turned off. I removed the back and I am trying to tell where the noise is coming from. I used a mic connected to the computer and the noise seems to be coming from the largest black cap on the middle of the board. Should i try checking or changing the cap first.
Gateway LCD monitor make hum or hiss when turned off
Mon, 09/07/2009 - 14:10
#1
Gateway LCD monitor make hum or hiss when turned off
I'm no technician, but this doesn't sound good - especially since it is making this noise when it's turned off. Does it still make the noise when you unplug it as well?
For safety's sake, I'd recommend replacing it. With monitors being so incredibly cheap these days, it's probably not worth "fixing."
yes it does stop as soon as AC power is removed. I removed the large cap the capacetance measures ok soe I extended the leads to isolate the sound. When I plugged in the power the cap is not the noise it seems to be undeneath it. Here is a pic from the back side of the bd. there are some components on the back too. The 8 pin IC in the middle looks like a 200d6http://www.alldatasheet.com/datasheet-pdf/pdf/115079/ONSEMI/NCP1200D60R2...
noise still seems louder on front side. Pic closer to the front with cap removed
After looking a little closer it appears this board only provides 2 wires for an output so I believe it is only a power supply. I know it was a bit of a risk but I plugged it in with no load connected and it still makes the humming noise so it appears it is have issues when there is no drain on it. Also with no output it did continue to buzz for 10 seconds after removing power.
a few ideas:
desolder then resolder chokes, coils, transformers
esr or replace mid size caps
clean up grounds
Thanks will try that later this week. I wish I had an ESR. I might have to try and replace them.