CRT strange Noise

[Rocky_D]

Hi, my CRT makes this new Sound. How is it called and how do i fix it? I am aware of CRT Safety Procedures. The about area were the noise comes from is on the image :] Changing Power cables does not change a thing and it is loudest on 4:3, 16:9 Panorama and Cinema also have it,but quiter. Only thing else i did on it was adjusting the G2 Voltage to remove red 'retrace lines'. btw should i clean it or leave it as is?

Edit: Sorry i forgot: Grundig MW 70-2690 NIC/TOP

 

[AncientBoi]

Allot of condensation marks in there, Besides the dust that can potentially produce short circuiting is what I see. js

And, Is that cracked?

 

[JuanMena]

It's air filtering to the Yoke Yolk. You need a special grease to seal any air gap from the cathodes to the Yolk.

 

[Rocky_D]

Allot of condensation marks in there, Besides the dust that can potentially produce short circuiting is what I see. js

And, Is that cracked?

View attachment 569132

Yes it is cracked

Post automatically merged: Apr 20, 2026

It's air filtering to the Yoke Yolk. You need a special grease to seal any air gap from the cathodes to the Yolk.

It's air filtering to the Yoke Yolk. You need a special grease to seal any air gap from the cathodes to the Yolk.
View attachment 569131

The Sound is coming from the Board :]

 

[AncientBoi]

Yes it is cracked


The Sound is coming from the Board :]

Then I think it is producing Shorts with the dust and condensation.

Also, I'd replace that item to be sure.

 

[JuanMena]

Yes it is cracked

Post automatically merged: Apr 20, 2026

The Sound is coming from the Board :]

Usually buzzing happens because air is getting zapped at high voltages inside the CRT, not board.

If you're totally sure it's board, then replace every single cap.

"Well of course that'll fix it without finding what it is", unless you have a professional grade Multimeter, you can't diagnose entirely what's causing the buzz. Most of these components are made to sustain high voltage for prolonged duration. Finding what is failing WHILE CRT IS RUNNING its ultimately not worth the risk... so just replace all caps.

If visual inspection doesn't show anything straight out bad (burnt components, blown caps, missing pieces, broken traces, rust, dust...) then you'll have to do multimeter tests with diagram in hand to corroborate your readings are okay.

 

[Rocky_D]

Usually buzzing happens because air is getting zapped at high voltages inside the CRT, not board.

If you're totally sure it's board, then replace every single cap.

"Well of course that'll fix it without finding what it is", unless you have a professional grade Multimeter, you can't diagnose entirely what's causing the buzz. Most of these components are made to sustain high voltage for prolonged duration. Finding what is failing WHILE CRT IS RUNNING its ultimately not worth the risk... so just replace all caps.

If visual inspection doesn't show anything straight out bad (burnt components, blown caps, missing pieces, broken traces, rust, dust...) then you'll have to do multimeter tests with diagram in hand to corroborate your readings are okay.

i'll give that a try in the future,thx!

 

[JuanMena]

i'll give that a try in the future,thx!

One way to check if it's Cap issue, now that I'm thinking about it... is to "push the CRT".
Depending on your model, you should have Picture Modes... right?

If yes... you can totally test if "Buzz comes from bad Caps" by doing the following test:
- Start CRT with whatever, movie, TV, game, whatever.
- Change CRT Picture Mode from whatever you're using to "VIVID" or whatever equivalent. If you have no Picture Mode (Sports, Movies, Vivid, Normal, etc.) by simply adjusting Contrast and Brightness values is enough.
- CRT's uses more energy to display a brighter, more colorful picture. If it's a capacitor failure, by the simple act of increasing Brightness or Contrast, the buzzing should (in theory) get highger, and viceversa, the buzzing should be lower at "crappy picture".

Before you go sticking your hand at running CRT's, do this test.

I used to fix my own aging CRT's, and I had a 27" SONY Trinitron. I used Rubber Gloves + Electrician Gloves on top AND I STILL FELT TINGLING IN MY HANDS... I had to fix my Convergence Rings because they moved and made the RGB beams misalign, I had to literally move these by hand until I made them match while the CRT was running.
Please, be careful!

 

[Rocky_D]

One way to check if it's Cap issue, now that I'm thinking about it... is to "push the CRT".
Depending on your model, you should have Picture Modes... right?

If yes... you can totally test if "Buzz comes from bad Caps" by doing the following test:
- Start CRT with whatever, movie, TV, game, whatever.
- Change CRT Picture Mode from whatever you're using to "VIVID" or whatever equivalent. If you have no Picture Mode (Sports, Movies, Vivid, Normal, etc.) by simply adjusting Contrast and Brightness values is enough.
- CRT's uses more energy to display a brighter, more colorful picture. If it's a capacitor failure, by the simple act of increasing Brightness or Contrast, the buzzing should (in theory) get highger, and viceversa, the buzzing should be lower at "crappy picture".

Before you go sticking your hand at running CRT's, do this test.

I used to fix my own aging CRT's, and I had a 27" SONY Trinitron. I used Rubber Gloves + Electrician Gloves on top AND I STILL FELT TINGLING IN MY HANDS... I had to fix my Convergence Rings because they moved and made the RGB beams misalign, I had to literally move these by hand until I made them match while the CRT was running.
Please, be careful!

I'm alive Changing Brightness and Contrast to highest does not Change the Noise but as written above it does Change with...eh 'aspect to ratio' ( ) 4:3 it is loudest, Panorama is much quieter, 16:9 and Cinema are alike + even quieter.

So from worst to best : 4:3-Panorama-16:9 and Cinema

 

[JuanMena]

I'm alive Changing Brightness and Contrast to highest does not Change the Noise but as written above it does Change with...eh 'aspect to ratio' ( ) 4:3 it is loudest, Panorama is much quieter, 16:9 and Cinema are alike + even quieter.

So from worst to best : 4:3-Panorama-16:9 and Cinema

Hmmm... yeah, sounds like a failing capacitor, maybe a broken fuse, a transistor... we won't know until you get the Scheamtics and measure each board component OUTSIDE OF CRT AND OFF.

The easy way: Go to eBay or I don't know... Ali Express or whatever and look for "[CRT MODEL] Repair Kit" which should contain every Cap, Transistor, Fuse that are common fail for that particular CRT model.
If you can't find any, then, turn off your CRT, discharge it, take out the board and start desoldering any component you might find suspicious, measure each with multimeter, compare readings with printed value and or corroborate with Schematics.

There is no easy way to diagnose, this is the only way I know, but you could try asking AI to check the schematics for you, just double check sources.


Might be a blown cap, a transistor failing to filter noise... who knows, after visual inspection go to multimeter measurements.