HP1955L Buzzing noise & interference
Hello, This is my first post so please forgive me if I miss out some vital info.
I have a problem with my HP1955L monitor from 2005.
The first thing to say is that it is still basically working, ie the picture is fine.
However it makes an electrical buzzing sound. I know all monitors make some some of hum, but this is louder and more of a buzz.
The volume of the noise seems to be dependent on how hard the monitor is working; switched on with a blank screen -> no sound; small dialog (like OSD only) -> minor buzzing; full screen picture -> loud buzzing.
If you put a headset on, you don't hear the noise, but when using a microphone (on a nearby computer) there is a very loud interference. I don't mean the microphone just picks up the buzzing noise, instead there is some sort of electrical interference so bad that the microphone cannot be used.
There is a slight but noticeable burnt smell.
I have dismantled the monitor; nothing looked obviously burnt to me. All caps looked fine (ie nothing leaking or bulging). The buzzing comes from the large transformer in the middle of the power circuit board (marked with a red x).
I have removed the transformer from the board and then soldered it back on again. No change to any of the symptoms. I also tried the same remove/replace with the double copper coil near the power input. No improvement.
As the board is working I haven't tried to measure any voltages as I assume they would be ok.
What might be causing this? How can I reduce the buzzing and stop the interference? Any suggestions as to what to try?
Thanks,
stvhop
I have a problem with my HP1955L monitor from 2005.
The first thing to say is that it is still basically working, ie the picture is fine.
However it makes an electrical buzzing sound. I know all monitors make some some of hum, but this is louder and more of a buzz.
The volume of the noise seems to be dependent on how hard the monitor is working; switched on with a blank screen -> no sound; small dialog (like OSD only) -> minor buzzing; full screen picture -> loud buzzing.
If you put a headset on, you don't hear the noise, but when using a microphone (on a nearby computer) there is a very loud interference. I don't mean the microphone just picks up the buzzing noise, instead there is some sort of electrical interference so bad that the microphone cannot be used.
There is a slight but noticeable burnt smell.
I have dismantled the monitor; nothing looked obviously burnt to me. All caps looked fine (ie nothing leaking or bulging). The buzzing comes from the large transformer in the middle of the power circuit board (marked with a red x).
I have removed the transformer from the board and then soldered it back on again. No change to any of the symptoms. I also tried the same remove/replace with the double copper coil near the power input. No improvement.
As the board is working I haven't tried to measure any voltages as I assume they would be ok.
What might be causing this? How can I reduce the buzzing and stop the interference? Any suggestions as to what to try?
Thanks,
stvhop
Attached Files
But today, I’m making an exception here. Why? No idea. Perhaps only because the repair details are still “fresh” in my head… which is ironic, given this is a 16 year old monitor that hardly anyone will care about today. It is new to me, though. 
I picked it up last November from someone on my local Craigslist. It wasn’t very close to where I live, but was close to a family friend that I had to go visit anyways. So after watching the posting on Craigslist for a few weeks and seeing it getting...
