hey,
first off im sorry if i put this in the wrong forum topic. second is my question.
i just got a viewsonic pureflat 17" crt display from a friend. when the screen is on it is perfect, but when it is off it makes this so very annoying high pitched whining sound. so my question is, is there anyway to stop this noise?
thanks
anyone? please its sooooooooo annoying, but i need the screen.
with the switch? That ought to do the trick.
dan k
The high pitched noise is most likely the flyback transformer / some other transformer vibrating. When a transformer is given a slighty non sine like AC wave form then an asymetric field can be created around the transformer which causes the laminations to vibrate.
Solution 1 : Get a power filter - audiophiles use these, but they cost a bomb.
Solution 2: I do not recommend this, but one really dodgy bodge is to dribble hot wax all over the offending transformers. When it cools, it solidifies and prevents the vibrations. Still I must say again..I DO NOT RECOMMEND THIS. DO AT YOUR OWN RISK.
And yes, hot wax dribbling really does work ppl.
A safer alternative using wax (which has a low melting and flash point), is using high temp hot glue. I have used this before to quelch this problem. It will be far less heat sensitive than wax, and it is quite cheap.
Just my 2¢
CM
If I'm understanding the comments here correctly, then the working theory is that the monitor, like many electric/electronic devices, is receiving a trickle of AC power when it's plugged in and turned off, and that trickle is causing the noise.
If I'm correct, then it seems the problem could be solved by inserting a switch between the monitor and the AC wall outlet or power strip.
The easiest way to do this would be to attach the monitor to its own power strip. Leave the monitor's power switch in the ON position, and use the power strip's on-off switch to actually turn the monitor on and off.
This dedicated power strip could be plugged into the wall outlet, or it could be plugged into another power strip - i.e. the main power strip you might be using for all your other computer equipment.
If you don't have an extra power strip laying around the house, you can pick up a small, cheap one almost anywhere for less than $10. Just make sure it has a power switch on it.
Matt
Classic macster...good post! I should have thought of hot glue and I agree it is a much better alternative.
Matt, I think you might misunderstand (or me). EDIT: Sorry missread your post. Your points are valid. Ignore---> The noise is most likely caused by (EDIT) not the flyback transformer which provides power to the high voltage components in the crt. This is only on when there are electrons being fired at the screen.
Like I said, the noise is caused by vibrations in the laminations in transformer. More specifically it is DC noise on the AC line, causing the non-uniform magnetic field.
As the monitor runs on the mains, you would expect the hum to be around 50hz, but the poster states it is a high pitched noise. Why? Im not sure if this is true, but from my understanding the AC is first converted to DC inside the monitor. This DC current is then chopped up into high frequency AC. This is because you can get away with a smaller transformer for a given power output as the frequency increases.
EDIT: Why the heck did I just say the stuff I said before again?
Ok i understand it is one of the transformers now, but how do i manage to find the correct one to put hot glue over?
Ok i have the monitor apart and i have been listening to it for at least an hour now and i have decided it is the flyback that us making the noise. so my question is, how do i stop it from making the noise? just poor hot glue or silicon all over it?
thanks for the responses.
First off, it's incredibly dangerous to have a CRT open while it's on, or even plugged in.
That having been said, a good thorough coating in hot glue sounds like it would work.
I know it is dangorous but i do know it is ok as long as it doesnt set fire to carpet or something, and just DONT touch anything on the inside and you should be fine.
Place hot glue over the windings / iron laminations.
Can you post a pick?
The nice thing about some hot glues is you can easily remove it from metal.
what do you mean by the windings/iron? do you mean the coils of wire wraped around the crt, or do u mean the fly back? no i cannot post pictures because i have no camera on hand.
I mean the flyback. If it looks like this...:
...then there is not much you can do with a glue gun, except perhaps put some hot glue on the back iron core.
i know what the fly back is but what would happen if i just covered the thing in hot glue?
I just could be crazy, but this high pitched thing annoys me whenever any TV is on. If I walk past a room with a TV on, but there's no picture, then I can tell by the noise. Is it just me, or could it be something to do with the TV and if so, is it preventable?
I'm glad to know I'm not alone in this high pitched hearing! I suppose it's worth a try, but going around and gluing up every TV you walk past isn't really an option.
The sounds you hear around any tv/crt are high frequency sounds cause by the tube itself. (I don't remember exactly, but that's what I remember) Most people under the age of 17, and some lucky adults, can hear these frequencies. Consider yourself charmed with a high fidelity hearing system.
CM
tvs and every other crt display doesnt bother me but this one is just alot louder than normal.. have you ever heard those emergency broadcasts on tv? well thats what this whine sounds like a little more high pitched and not AS loud but it is still loud.
I'm 26 and I stil hear it. It annoys me to no end at time, other times I don't even notice it. It really gets bad when I have several CRTs goning, then it's a bunch of varying frequency whines. Ick. Must be why I like LCDs/laptops better.
There isn't anything you can do. I can tell whenever any CRT is on, even if it's in another room. I've just chalked it up as being part of life.
LCDs annoy me too. Almost all of them make a high pitched whine.
The fact that you can hear THAT is just plain weird.
I'm 36 but I still have very good hearing - and my LCD TV makes a fairly obnoxious noise. If my TV area and my hi-fi stereo listening area were in the same place, it would be really annoying. Fortunately my LCD-based iMac makes no such screen noise that I can detect.
Matt
That's most likely a high frequency whine from the backlights. I notice it on my LCDs when I put my ear up to them.