any idea why my TV is whistling?

foreign_correspondent

I have just been given a big CRT TV, it was my aunts and never whilstled there, but it keeps intermittently making a high pitched humming noise.

Any ideas?

aliEnRIK

Contrast is probably way too high

foreign_correspondent

I will have a look, ta!

aliEnRIK

If it is, it will do it when there are whites (or a lot of white) onscreen

nobby24

You're not watching The Roger Whittaker Show are you?

theartfullodger

Is the rest of the room dark & is it nervous??

Cheers!

Lodger

kwikbreaks

Usually caused by an excess of skin tones on screen.

What are you watching?

knowledgepower1

Probably fancies what you are wearing..

adouglasmhor

Turn it off let it cool down, vacuum carefully with the hose all the vents at the back, the thyristors inside could be overheating.

bookduck

Oh, so you are quite a young person:) Older folk do not hear this high frequency any more.

it is usually the line output transformer that causes this and is resonating at probably 15.625kHz

Firstly this device generates literally about 25000V. If faulty, or faulty circuitry then can co up to 50000v. Even when the set is off the capacitors and the tube still may store a charge of many 1000's of volts. If you do not know what you are doing and are inept with electricity and realize that the spark could easily jump half an inch, then I would keep well away! Hoowever the ampage is probably not enough to kill you.

With the tv switched off and unplugged from the socket, what I would do (after reading the above paragraph again) in to vacuum out the dust, check the joint on the pcb of the transformer and resolder them all - even if they look good, also tighten the holding screws of the transformer, also possibly tighten the transformer assembly bolt (if visible).

Still making a noise? while switched on take a plastic ruler and push the transformer to determine what is exactly vibrating you may be able to stop it with paper wedges, or a dab of epoxy. I would not do this while it is switched on though:eek:

Superglue may be another solution, but you will have to check first to see if it conducts and it's insulation properties, also it tends to deteriorate with heat.

At the end of the day it may be the coils are vibrating, and these are normally sealed in compound:(

http://en.wikipedia.org/wiki/Flyback_transformer

robpw2

its done something and is feeling guilty ..