CRT making strange bell like noise.

[c.ruel]

My second hand CRT is making really strange bell sounds now and again. It sounds a bit like a doorbell. It is not constant but just every now and again there is a bell like sound and the picture goes funny for a second, sort of blurry and then back to normal.

Is it on the way out?

Any help with this would be really appreciated because then I can start saving/ looking for a new monitor now.

[Zak33]

any CRT (monitor or tv) making that noise during use.. is going to stop working soon.

they often make it when turning ON or OFF>.. but not during use.

Some monitors have a DEGAUS function which switchs off the cathode ray gun and whacks it back on to clear the screen.. but its for YOU the USER to do.. not the monitor.

[scaryjim]

Yeah, sounds like it's regularly degaussing itself. Not a good sign I'm afraid - it means either the monitor's on its way out or there's something gone screwy with the controls. As Zak says, it should really only do that when you tell it to by pressing the "degauss" button (which most CRT monitors have somewhere).

I suppose it's possible that your monitor has an auto-degauss function, but if it's triggering regularly enough for you to be worried by it then it's probably starting to go on the fritz. If you can find it I'd dig out the manual (it might be available online?) and search through it for degauss, which should find you any references to an automated system or what to do if it starts degaussing regularly.

[peterb]

Certainly not healthy, although it depends what is causing it as to when it will fail. If ythe picture flickers or dissolves, them it is likely to be the EHT ccts, which are the components under greatest stress. The EHT voltage is generally around 25K and these are often the components that fail, rather than the tube itself.

De-gaussing was usually applied to shadowmask tubes, and consisted of coils round the outside of the screen end of the tube, and in televisions these were magnetised at switch on, via a negative temperature coefficient device, which reduced the magnetic field gradually to de-magnetise the shadowmask. A magnetised shadowmask leads to colour impurity and convergence issues. During the degaussing process the picture will wobble or shimmer and colours will be distorted.

High end monitors also had shadowmask tubes, which were generally user controlled, again applying a magnetic field to the shadowmask to demagnetise it.

Your monitor may give you many months or years of service, but it will be getting quite long in the tooth now so if you want a replacement (and they are getting hard to find - I rue the day I took two to the tip about 5 years ago) now is the time to start looking.

Because of the high voltages involved, you should not remove the covers of a CRT monitor. Apart from the high voltage, there is also a small risk from low level X-ray radiation. There will be screens and shielding round the danger areas, together with warning signs. Heed them!

[Xnemesis]

Could be leaking capacitor in which case your monitor may go bust anytime soon.

[c.ruel]

I don't want to talk it up but it has seemed pretty stable lately. The only thing I can possibly think of was that the sun was shining on it really instensely while this "error" if you can call it that. Maybe the sun was making it over heat.

The noise it makes is different from the sound it makes when it degausses.

[Xnemesis]

I don't want to talk it up but it has seemed pretty stable lately. The only thing I can possibly think of was that the sun was shining on it really instensely while this "error" if you can call it that. Maybe the sun was making it over heat.

The noise it makes is different from the sound it makes when it degausses.

Hi it maybe capacitor then since the pitfall of all capacitors is heat ceramic ones last better to heat but have smaller capacitivenss the electorytic ones are of larger capacitive range however are prone to heat and thus fail overtime due to heat.

[Chipps]

It may also have something to do with your raster line refresh. Old CRT (Cathode-Ray Tube) monitors update their screens with a low energy electron beam which would start at the top of the display and work it's way to the bottom refreshing the picture 60 times per second (hence 60Hz refresh rate). When this raster refresh system begins to go on the fritz, your monitor may make a constant high pitched squeal noise or a random clicking or dinging sound. Not sure if it would account for your picture fuzzing out on you. The previously mentioned DEGAUS would explain the shaky fuzziness, but I've never heard of a monitor degausing itself on it's own.

Either way my friend, I think your next monitor purchase should be of the LCD type

Cheers!