My roommate has an old CRT that is driving me nuts
I can hear it through several rooms. I have always been extremely sensitive to these but with the advent of modern flat screens I have been relieved. Is there a way to quiet them down a bit? Hoping some old TV repairman out there can give me some advice
-bird
I can hear it through several rooms. I have always been extremely sensitive to these but with the advent of modern flat screens I have been relieved. Is there a way to quiet them down a bit? Hoping some old TV repairman out there can give me some advice-bird
It's like an ice pick in the ears when it starts. My CRT started this last summer and it emanated from the flyback transformer. Just o you know - LCD/LED tvs aren't much better. After a while the transformer hum, and they go from amost silent to loud depending on the color composition of the images on the screen. Worse still is when the switch mode power supplies start! They ring even when the bloody things are turned off, and I have to unplug a Samsung LED that is particularey offensive. I would love to hear a fix for both the flybacks on CRTs and the smps on LCD/LED displays.
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From the poking around on the interwebs I have been doing this flyback transformer seems to be what it is. I wonder if the transformer can be "tightened" or re-glued to stop the laminations from oscillating? I do know there is 20kV in there
Knock on wood I have had no issues with my Samsung LCD.
Hi,
Well it would have to be a very old CRT to have the typical
horizontal tubular transformer used for the CRT tube.
Yes you can coat it with whatever to damp it.
FWIW the original LS3/5A was designed with an excess around
16KHz to pick up any audio coupling of the PAL line frequency.
Its very odd 16KHz can travel through several rooms,
as it basically cannot, full stop, physics and all that.
rgds, sreten.
Well it would have to be a very old CRT to have the typical
horizontal tubular transformer used for the CRT tube.
Yes you can coat it with whatever to damp it.
FWIW the original LS3/5A was designed with an excess around
16KHz to pick up any audio coupling of the PAL line frequency.
Its very odd 16KHz can travel through several rooms,
as it basically cannot, full stop, physics and all that.
rgds, sreten.
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Hi Sreten, I am without a question hearing it through two walls, I do understand higher frequencies have a harder time passing through objects, my 5GHz wifi doesn't have nearly a good a signal downstairs as the 2.4GHz. If 2.4GHz can travel through several floors and walls I am sure 16kHz can.
Something electromagnetic is causing the oscillation, which I can hear. Not sure what you are telling me.
I wonder if the high pitched tone famousmockingbird is experiencing is also coming through other electronics in the other rooms? LED residential light bulbs emit several tones, as can some filaments in incadescent bulbs. Old or noisy contact dimmer switches can get really bad, too. It's also possible that he meant to say the noise is present while the doors are open, in which case it could echo and travel.
Mine was purchased in 2005. I think famoumockingbird and myself should seek new flybacks. They become quite warm, so I am cautious about raising the temperature with damping materials. I read about dipping them in wax, but I've not seen a follow up of the lifespan.
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Hoping some old TV repairman out there can give me some advice
-bird
Err, lets have a bit less of the old shall we
Line whistle was the bane of many service engineers. In a CRT TV it can come from any number of components, not just the LOPTX (line output transformer). Scan coils, linearity coils, coils/chokes used in convergence circuits can all scream loudly. Many times the noise is a mix of harmonics and is often audible well outside the room, sometimes outside the house.
Fixing it is darned difficult because the magnetic energy involved is so intense. Yacht varnish for dipping transformers and coils, hot araldite poured onto chokes and coils, its all been done before and often with only very limited success.
SMPS tend to be a different as they can run chaotically in burst mode emitting something more like white noise than a definite high frequency note.
Be careful if you are meddling with CRT TV's. 20kv is low voltage portable TV territory
and the aquadag coating on the CRT is in effect a capacitor that will stay charged for days. Something to bear in mind if you attempt to remove the anode cap.Err, lets have a bit less of the old shall we
Hahaha okay let's go with "wise" TV repair technician
I was assured it will be upgraded to a more modern flat screen set so I am no longer planning to open it up. As you said the noise was the bane of some professionals so I don't think it will be worth the headache to fix.
Hahaha okay let's go with "wise" TV repair technician
That's better
The LOPTX is driven hard by a rectangular wave applied to the line output transistor (I'd hate to call it square having spent hundreds of hours looking at these things
) and I suspect the acoustic energy from many is anything but low level. Harmonics... yes, and then some. Its a noisy mish mash when everything driven off the line output stage is taken into account.- Status
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